Stumped - incessant cycling and pressures all out of whack (

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Stumped - incessant cycling and pressures all out of whack (

Postby james92se » Fri Mar 03, 2017 6:29 pm

This is an LS transplant with complete 01-02 Chevy Camaro ECM/wiring/electronics/compressor/pressure switch. We are not using the GM condenser, evap, or expansion valve however. Only thing "custom" are the lines/hoses that my brother and I built which connect the GM compressor to the evap/condenser.

Started with a completely empty system and brand new compressor. Vacuumed for an hour, let it sit for an entire day to verify it held vacuum - it did. Chevy calls for ~ 1 lb 8 oz of R134a. Initially we added 1 lb 4 oz and compressor would only stay on for about 2 seconds at a time, cycle off for about 10 seconds, then turn back on for about 2 seconds. We thought no problem, just low on refrigerant. Added more and more refrigerant and eventually got up to 1 lb 12 oz of refrigerant, but the compressor behavior never changed a bit.

Static pressures were spot on - 65 degrees ambient temp, and both high and low static pressures equalized right at about 65 PSI. However, when you run it, this is all it does incessantly - compressor will only cycle on for a couple of seconds then click off, over and over and over. Judging by what the pressures were doing, we thought absolutely either stuck expansion valve or dead compressor. We replaced both the expansion valve and compressor, vacuumed and charged again and it's STILL doing the exact same thing. This is what it does - any ideas?

https://youtu.be/E2u5kcwRQB4
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Re: Stumped - incessant cycling and pressures all out of wha

Postby Tom Greenleaf » Fri Mar 03, 2017 8:19 pm

Couple thoughts/question:
1. It's a bit cool at 65F to get good results.

Q: Is this stuff really new, rebuilt and oil spun thru compressor prior to charging? If not it may have burned out just that quick! How much oil used to do all this?

2. Pressures shown in video reflect a compressor that doesn't compress gas enough so it cycles off and would if those pressures are accurate.

Thought + question: What do you really mean by "transplant" from those years of a Camaro? The system capacity may not be what is listed for that car anymore but did match my look up.

I'll never be sure but cycling compressors on a CCOT system I think this should be may be using the HIGH pressure switch especially if more than 2 wires it shuts down compressor when high side is low as well as shut down electric fans as it thinks they aren't needed or thinks system really has such low pressure don't allow compressor anymore even if errant.

Try looking at the temp/pressure chart and see how hot the high side gets right at compressor and bet cool as your 65F temp plus maybe some engine heat?

In short I doubt that compressor is compressing and no good. Now the problem could be debris?

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Re: Stumped - incessant cycling and pressures all out of wha

Postby james92se » Fri Mar 03, 2017 10:00 pm

Tom Greenleaf wrote:Couple thoughts/question:
1. It's a bit cool at 65F to get good results.

Q: Is this stuff really new, rebuilt and oil spun thru compressor prior to charging? If not it may have burned out just that quick! How much oil used to do all this?

2. Pressures shown in video reflect a compressor that doesn't compress gas enough so it cycles off and would if those pressures are accurate.

Thought + question: What do you really mean by "transplant" from those years of a Camaro? The system capacity may not be what is listed for that car anymore but did match my look up.

I'll never be sure but cycling compressors on a CCOT system I think this should be may be using the HIGH pressure switch especially if more than 2 wires it shuts down compressor when high side is low as well as shut down electric fans as it thinks they aren't needed or thinks system really has such low pressure don't allow compressor anymore even if errant.

Try looking at the temp/pressure chart and see how hot the high side gets right at compressor and bet cool as your 65F temp plus maybe some engine heat?

In short I doubt that compressor is compressing and no good. Now the problem could be debris?

Tom


Yes I know it's a bit cool, but I've overhauled/charged the AC systems on my other cars before when it's been in the 50's with no issues. Regardless, don't have much control over the weather and the LS swap has been completed now and want to go ahead and get this AC working to finalize the car.

The first compressor was a brand new GM AC Delco. The original expansion valve was confirmed working before the LS swap - this was a perfectly good running car with only 80k miles when we pulled the drivetrain to do the LS swap. The second compressor is new but Chinese, as is the second expansion valve - but again exact same results each time.

Both compressors sat upside down for 30 minutes with ~2.5 oz of oil in them to soak into the front seal, as well as spun by hand a dozen or so times. Total system oil is about 7 ounces - a little low for the Camaro (which IIRC shows to be 9 ounces) but again this is not in a Camaro - this is just a Camaro LS powertrain/wiring/PCM swapped into a little roadster. The total system oil for the roadster was 4 oz, so we kind of went in the middle at ~7 oz. I can't imagine the compressor burning up due to no oil as it's only been ran about 20 minutes total and we know for certain it's not dry or anything as we measured all the oil going in.

I should have clarified everything is brand new on the entire AC system other than the original roadster evaporator. The OE system in the roadster was in perfect shape - car only has 80k miles on it and we only took the car down and gutted it specifically for the LS swap. Condenser is new, all AC lines brand new - I know because we built them, new drier, new expansion valve, new compressor (remember 2 times now), even new GM pressure switch so I highly doubt there's any debris in the system anywhere.

Yes this has the three wire Camaro high pressure switch. Again, we are using the full LS Camaro PCM/wiring/everything - so this AC system should function exactly like the Camaro despite it not being IN a Camaro. We have it wired 100% confirmed exactly like this:

Image

It seems like it has to be an electrical issue. We now almost wonder if the PCM is doing goofy things. Doing some research it seems like PCM troubles are not uncommon as the cause for AC issues in these GM's.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby Tom Greenleaf » Fri Mar 03, 2017 10:40 pm

I'm tired - sorry: OK, I don't show this car with an expansion valve at all it's listed as a CCOT = Clutch Cycling Orifice Tube set up. Orifice Tube should be in the condenser which you said isn't part of the total swap over.

Looks like this......
Image

That's where it turns from warm/hot liquid to a gas and if missing in this condenser it's just pumping gas (134a?) around in a loop doing about nothing.

PCM if working is telling this to shut off compressor then allows it again which is my guess why it's cycling and you couldn't have any cooling effect.

If you tried to jump a high pressure cut out switch you may have blown the PCM control of the A/C already OR it needs to be reset probably by a dealer's equipment to do that. It's quite "married" to the car it belongs to not just some PCM you swap around.

Any A/C codes showing?

I'm not sure here for you. This just sounds like condenser lacks the orifice tube totally and if an X-Valve set up it isn't listing parts that way?

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Re: Stumped - incessant cycling and pressures all out of wha

Postby cornbinder89 » Sat Mar 04, 2017 1:00 am

Ok, in your video BOTH the low and high side gauges dip when the compressor cuts in, so either you have them both hooked to the low side or you have a restriction between the highside tap and the compressor.
2nd, the original Chevy system was CCOT system as mentioned, so the controls will be wrong for an expansion valve system.
Expansion valve systems are much more forgiving of refrigerant amount as the excess is stored as high pressure liquid, CCOT must have the correct amount as the accumulator only stores low pressure gas.
With a Tx system, you need a receiver to store liquid refrigerant and a safety cut off switch to shut the system down if it runs out of refrigerant. That is the minimum, you may need a fan switch to turn on a condenser fan if you aren't using an engine driven fan, and can add more safeties for high pressure.
On a Tx system the low side can dip below 28 PSI if the Tx is throttled closed or if the system is low
The CCOT work different, and when the accumulator pressure reaches aprox 28 psi the low side switch will turn off the compressor.
You are mixing two in compatible control systems. Either forget the computer controls for the Tx system and install plain old pressure switches, or pull out the Tx and evaporator and replace with an orifice tube and accumulator.
It is not possible to run a system that is 1/2 one way and 1/2 the other.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby Tom Greenleaf » Sat Mar 04, 2017 12:02 pm

Thanks Cornbinder89 for your strong insight to Tx set ups.

It's been found that the "O" tube was put in some hoses right at condenser and if again at condenser there's another has different but working a little results. These were "Made Up" hoses apparently so can't know.

BTW: No LPCO switch was listed for this suggests the PCM takes in info thru a "Thermistor" instead of pressure by temperature converted to electrical information sent back to PCM to allow or shut off the clutch.

Again: Fans do not operate until pressure shows a certain higher pressure so in effect if too cold not needed nor at adequate speed you simply save use on the fans as air speed alone is enough.

Without a LPCO to jump if charged that way into a well held vacuum using engine not pushing in refrigerant should be liquid first as much as it will take into the vacuum, no engine running. It should cycle on enough to finish off the charge with oil flowing some but question how this was done. I still think this compressor may be ruined already from oil starvation new or not even if pre spun with oil it would take a long time at low ambient temps without adding heat or source refrigerant heated up machine or not you can't have that equipment that cold!

Again - the Powertrain Control Module (PCM) could easily be part ruined if anything it controls is jumped to force compressor. FYI they generally do NOT add power they allow ground to an item to operate in some, not all set ups. They must match or be re-flashed in some cases or wouldn't work well or at all? Can't know that as this is transplanted parts unsaid so far exactly what from what,

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Re: Stumped - incessant cycling and pressures all out of wha

Postby cornbinder89 » Sat Mar 04, 2017 3:00 pm

I freely admit I am not up on the latest systems, but what I'm seeing and hearing on the clip posted, is not a compressor problem. The compressor is pulling down the low side gauge but also the high side gauge.
That to me says 2 things, one it is moving refrigerant, and two, that either the high side port is placed in the low side of the system or that there is a restriction (like may be a orifice tube in the condenser or a "packing peanut that is blocking flow) ahead of the high side test port.
CCOT system, no matter how they are controlled, draw the low side down to a pressure that equates to around 32 deg evaporator temp, then cycles the clutch, the accumulator is just a large container that allows the system pressure to stay there as long as possible before clutching in the compressor again, heat load determines how long that is.
A Tx system works kind of the opposite, the compressor runs and stores the refrigerant in the receiver, and the Tx allows enough into the evaporator so it all boils before it leaves the evaporator. There is a thermal switch to turn the system off if the evaporator drops below the frost point.
Two different systems and two different control perimeters. If you put CCOT controls on a TX it Will short cycle.
On a Tx system, the low side can, and often is below the pressure that would equate to 32 deg, which is why you can't charge a system by pressure alone. The Tx valve may need to throttle the system so only a small amount of refrigerant is needed to cool the evaporator to the point where the outlet is at the set point of the valve.
If he does have a Tx valve in the system, he needs to build a Tx valve control circuit, or build a system to match the CCOT controls, you can mix and match.
EDIT: I would also add the controls are working correctly for an OT system, cycling the clutch when the low side on the gauge reaches about 28 psi. so the controls are working and properly, just not properly for a Tx system.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby cornbinder89 » Sat Mar 04, 2017 4:11 pm

From where I sit, the Air Conditioning pressure sensor does 3 things. 1st it cycles the cutch when the pressure in the accumulator equates to an evaporator temp of around 30 deg , 2nd it prevent the system from operating if the pressure indicates a low charge, and 3rd it controls the evaporator fans. All of this is done via PCM.

If you could build a sensor to replace the pressure sensor with a evaporator temp sensor, that followed the same curve and cycling the clutch when the evaporator reaches around 30 deg. You would then need something to control the other two functions of the pressure sensor, namely low refrigerant cut out and fan control.
If you are good at building digital circuits it is all doable, but you better know what you are doing because the wrong signal or voltage can fry things in a short order if you get it wrong.
You could make the PCM control a Tx system, but it would a challenge.
Also does the system you have now contain a receiver? Does it have an accumulator? We really need to see both the A/C system as it is now, and the controls as they are now.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby Tom Greenleaf » Sat Mar 04, 2017 4:54 pm

Shows an accumulator in a parts look up. That can still be wrong?

Like this...........
Image

OK - another for a little more claimed either R-12 or 134a compatible with "o" rings and any gaskets. Has desiccant in it listed. Taking a look the port is probably a plug or threaded to make either a switch or a LOW port or if application for it's use not needed it's a plug.

The wiring diagram is not complete. Camaro, Corvette and similar performance cars especially would shut off electric fans not shown in the diagram nor shows a WOT cut out.

Where checking this stuff fools people is that dang PCM is also instantly doing an algorithm to adjust idle speed, fuel delivery and timing factoring in load on engine, speed of vehicle and throttle position all at once!

Since no low pressure physical switch is listed the temp sensor is also called a "thermistor" as said doing the same thing as a LPCO. It wouldn't allow engagement of compressor on wrong temps alone. That's all to be considered and testing each thing out could take mega thousands of bucks of tools to read live data is within perimeters.

Opinion: It's too new to go fussing and changing things out from another vehicle thinking they are all the same controls doing old fashioned things with a PCM that could easily be confused and ruined.

This vintage would have codes to say what it can see or not see how it's hooked up now only tells you it can see what's working and which circuit not item is wrong which is up to the tech to decide.

Can do this but take tons of stuff for check to get all set properly which it either isn't or isn't reading it so system doesn't know what to do with itself,

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Re: Stumped - incessant cycling and pressures all out of wha

Postby cornbinder89 » Sat Mar 04, 2017 5:11 pm

I don't know what he has, there are two systems tried to be married together. The donor powerplant would have one thing and the unknown chassis has another, so we don't know what is on the car at the moment.
My last post was to acknowledge that it may be possible to get he PCM to control a hybrid system (one made of two systems spliced together) but it would take a lot of circuit building experience.
I don't think (or have enough info to think) there is a component failure, but rather a misapplication of parts.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby cornbinder89 » Sun Mar 05, 2017 2:52 am

James92 PLEASE let us know what you find out, it is how we all learn. I would be very interested in the outcome and what the solution to the problem is. Tom and I have given our best guess as to the problem, but you have it in front of you and can see the results, we cannot. We don't always have the answer, but if we all put our heads together on the problem we might solve it.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby jonathan_ed3 » Sun Mar 05, 2017 7:02 am

There is no packing peanut or human caused restriction anywhere. it's been apart twice at this point.

The ac diagram is complete.

The pressure ports are not installed on the same line.

The LS1 pcm controls fans, WOT shutoff and all other necessary items via other outputs in the PCM.

From what I understand, the LS1 compressors should never "cycle" unless there's a pressure problem. They just reduce or increase capacity/output but they're basically just always on. (Variable displacement)

Forgive me if I'm not using all the exact proper terms for everything:

Honda evap core with with block type expansion valve. Both are factory R134 units.

The service fittings are mounted directly off the firewall/expansion valve block as this was the easiest and most convenient way to do so. (We do still have an original Honda high side port in between the drier and the condenser. We can use that if necessary to check pressure)

The GM pressure sensor (sensor NOT switch) is mounted in the high pressure line between the Honda expansion valve and the Honda drier.

In the GM cars, this sensor is literally the only sensor in the entire system. Apparently this is all they need since the clutches don't cycle.

So one side of Honda drier goes to the Honda expansion valve and one side to Honda condenser. this hardline between the drier and condenser is original and still connects to its original locations. It has the original Honda high side service fitting in it. We just bent the line a little bit to get it move out of the way to clear the other hoses. But it still connects to the same port on the condenser as originally and to the same port on the drier as originally.

Although I don't think it happened or could have happened and this system still hold pressure like it is, if somehow this line I'm talking about right now got kinked could it present these symptoms?

Originally the drier was mounted up near the top of the condenser. We relocated it down near the bottom because we needed the other real estate. Could relocating this have caused an issue? Does it need to be mounted "high" for any reason?

The low side pressure line comes off of the expansion valve (has service fitting right there) then goes directly to the suction port on the LS1 compressor.

The discharge port on the LS1 compressor goes to the condenser.

There is no orifice tube or accumulator in the system.

Basically we stuck the LS1 compressor in the middle of the Honda system and made custom lines to attach it

This is how others with LS1 swaps have done it in other platforms and theirs works great. Using expansion valves and NO orifice tube or accumulaters. Again, please note that all of these cars are using GM LS1 variable displacement ac compressors in a system that was originally an expansion valve system. They're swapping compressors. Keeping their expansion valves. Wiring up the PCM and they have cold air.

So in theory it might not work (mixing orifice tube components with expansion valve components) but somehow it does?

See BMW LS1 swaps with AC:

https://www.bimmerforums.com/forum/show ... 1-E36-swap

Nissan 240sx LS1 swap with AC:

http://www.rigidracing.com/2013/09/02/a ... lete-post/

FD Mazda RX7 LS1 swap with AC:

http://www.norotors.com/index.php?topic=23657.0

What am I missing? What's inherently different about these cars that they can make it work using expansion valves but it doesn't work in this situation?

Really appreciate the insight guys. Hopefully you can help us solve this. We're ready to finally enjoy this car. Everything has gone wrong on this build and we're just tired of the headaches!
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Re: Stumped - incessant cycling and pressures all out of wha

Postby Tom Greenleaf » Sun Mar 05, 2017 11:44 am

James and or Johnathan?:

I just looked back to top link of your video > https://youtu.be/E2u5kcwRQB4 < if that was any vehicle knowing the temperature pressures both are too low and get lower when compressor sounds like it engages - any type that wouldn't produce cooling if a golf cart or a NASA design for something.

You are stumped, cornbinder89 and I am stumped also. This creation of assorted parts shouldn't totally matter for showing pressures that are credible which they don't by that video suggests it's just pushing whatever amount of refrigerant is really in this around in a loop doing nothing much. So from there I would wonder if ports where checked are in correct locations or maybe, just maybe the refrigerant was lost you thought went in. It held a vacuum which is 14.7 PSI of atmospheric pressure OUT of the vacuum only not the higher pressure of refrigerant gasses INSIDE the system so is a good clue but not conclusive it is tight. Forces on seals may work one direction and not the other.

That aside and I'd verify that the charge is in fact in the system by recovering it and measuring how much really comes out. Process of elimination if a silly as it mostly leaked out. Perhaps a sniffer would help along with touch/feel for temps of lines and items or touchless infrared thermos to see what is really there if in fact it is refrigerant. Mind bending.

With this site you should know. For right now site is 99% cornbinder89 and myself. I can't find the original owner, second owner, ACProf but can find Nacho (Ignacio) reachable thru PM or there's a forum/board at www.AirCondition.com as well run by a CJB. Nacho has his own site mostly Spanish only but would and does speak and understand English and a very wide assortment of vehicles and situations.

The job now is to try to find you the right help as I'm lost except for what I just suggested. Nacho should answer a PM listed or click on his user name at home page. All others have not responded to me for quite some time now. Site is and has been in trouble and don't even know who pays for it?

Your links just now just led me to web searches for some reason didn't help me understand.

In short I can try to find you some other help if Nacho doesn't respond to you perhaps find another who can suggest away and things to check.

Wish you luck and can't really help much more on this and would appreciate just because when you do find the issue to please post it for archives anyway to be of use to another.

Best of luck,

Tom Greenleaf
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Re: Stumped - incessant cycling and pressures all out of wha

Postby cornbinder89 » Sun Mar 05, 2017 3:29 pm

As I said before the newest stuff isn't my strong suit. I do understand that your dealing with a sensor, not a switch but it uses the same perimeters to make the same "calls". The PCM can utilize the info gleaned from the sensor to control both the compressor and the condenser fans. My guess is the pressure problems you are showing on the gauges are triggering the PCM to shut down the system as it doesn't "see" the expected signal (pressure) at the sensor. It may be interpreting as a low system or just "out of range" from what a normal system should be.
As Tom pointed out, regardless of system, a high is that dips when the compressor is on, will not produce any cooling. That is a truth regardless of type or construction of system or parts used. That is where I start my diagnostics. Try taking a high side reading at the Honda port, if you get the same than you may have to add a port closer and closer to the compressor until you see some pressure rise when the compressor kicks on. To be sure the
Placement of R/D make no difference in terms of elevation within the system. Most often they are in the lowest point but some (roof mount condensers) have them in the highest point.
Until you get to the root of the high side pressure, everything else is moot. The high side pressure on the gauge points to a blockage between the gauge and the compressor, that is a hard clue, regardless of what else has been changed, the high side will have more pressure as the low side drops when the compressor kicks in, if the low side drops, the refrigerant MUST be going somewhere, and to do that it MUST be compressed into some space, the question is why do you not see that on the gauge? Answer, there is something preventing it reaching the gauge port. If the compressor was faulty there would be no drop in the low side, so with a drop we know it is moving refrigerant.
I don't have the answer, but if it were in my shop, this is what I would do. I would buy a bunch of fittings to splice into the high side (either in hose, or compression for hard line) and take readings closer to the compressor. I want to find a point when the high side shows a increase when the compressor kicks in. Once I did that, I know my problem is between that fitting the next one further away. Once I solved that mystery I could replace the chopped up line with a new one and move on.
There may be more than one problem, but the high side pressure problem must be tackled first to prevent chasing your tail. Throwing parts at it you might get lucky, but you have an unusual system and we don't know this is the only problem. Attack it methodically and you WILL solve it.
I am a person who has built my own systems, including one with two compressors, condensers R/D's and one expansion valve and evaporator, talk about chasing you tail! It took a long time to get that one sorted out.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby cornbinder89 » Sun Mar 05, 2017 6:58 pm

Hint, If you are just using it for diagnosis, you can quickly add test ports on hard line with "piercing taps" these are made for many size line, and while I would never leave one on an automotive line, they can make quick work of adding test points. They don't require the system to be emptied to use them
The draw back is they are mostly made in 1/4 flare, which will require and adaptor if you Acme threads on your gauge (134a). Once the diagnostics are finished, you can replace the lines with the taps. I think the last time I purchased them it was from WW Grainger or McMaster Carr.
This is what I'm talking about:
http://www.ebay.com/itm/BPV31-SUPCO-Bul ... SwopRYitUx
or
http://www.supco.com/web/supco_live/sea ... &x=11&y=11


they show them up to 7/8" line
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Re: Stumped - incessant cycling and pressures all out of wha

Postby jonathan_ed3 » Mon Mar 06, 2017 6:34 am

i appreciate all the responses.

we tested pressure again today but this time we tested on the high side line between the drier and the condenser at the original Honda high side fitting.

We also manually powered the ac clutch, bypassing the pcm entirely so it didn't override anything via the pressure sensor.

Exactly the same results. No matter how long we let it run, the high side pressure never materialized like it should be.

We did however notice that the schrader valve at this location started to leak after we pulled off our gauges. Although to be fair we are fairly certain it was not leaking beforehand, as our pag oil is UV tinted and there was no trace beforehand. It's leaking pretty well now though, so who knows.

Ordered another high side service port and we'll splice this in between the compressor discharge and the condenser.
We won't have a chance to work on it really soon anyway due to our work schedules so it may be next weekend before we can install the splice and mess with again.

We'll evacuate then fix the one leaking port, fill and test again.

im hoping the pressure is good there at this new test location, as then I know I've got a condenser problem (even though it's brand new)

If the pressures look crappy there yet again does this mean bad compressor? Remember this would be two in a row from 2 different manufacturers.

Or very low charge?

Or???
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Re: Stumped - incessant cycling and pressures all out of wha

Postby Tom Greenleaf » Mon Mar 06, 2017 10:49 am

Some random thoughts:
About the leaking port: If a ball valve type may do and rely on the cap is the final seal. Either way a spit test it should bubble too long or charge could be way too low.

Can you measure the weight of what you recover OUT of it? It would be very telling if it wasn't what you think you put in or real close.

Oil: It only moves along with compressed refrigerant or stops flowing along so may be pooled in some spot doing nothing.

Condenser: If super HE I've only heard of a couple successes at cleaning one out only by laying it flat if suspect defective or debris. Some flow patterns if you lose one flat tube it takes out 3 so quickly bypasses it or fails to transfer heat which so far is moot at those pressures if accurate.

This variable compressor still if in a vise and spun should pull at your finger at inlet and push a finger away at the other. If you found any black/dark junk something went wrong quickly?

Low oil charge if system was normal? Most are noisy, work but subject to early failure. Too much cooling and pressures usually show erratic - this didn't yet did it?

IDK - use an infrared touchless thermos a lot to know real temps and pressures of a contained known gas. Cheap ones even can work fine or be errant. Size of a key fob even just fine. Test you body temp for accuracy. Have one in hand now. Room temp is 77.4F. Laptop PC screen is 80.5F. Where disc bakes this thing is 94F. I'm in a kitchen and an ice cube is 1F in freezer. Under my tongue was just 94.5F fine as I didn't hold it accurately for body temp anyway.

I don't know how to work without the thing can be had for about $20 more for a pointing lazer one just used on a FHA heat duct was 115F about right as heat shut off a while ago.

Either can follow a line of refrigerant or anything solid not vapor alone. Needs something solid to work and not too windy.

Just a tool to help know what's happening where.

Pressure chart for refrigerant's in automotive use below..................

Image

I find this spot on testing tanks if they need heating up vs temp of a system if refrigerant will flow by itself or has equalized.

Reasons: It's nasty cold where I am and have to put both a vehicle and source refrigerant in heated area or results are all wrong. I know it can be done with other tricks.

Side note: I can heat my whole shop to 100F but takes hours no matter how cold car and equipment is. I'd rather not at all and wait for the right natural temps when possible which it isn't of course.

That isn't the whole issue here as you aren't getting any credible readings of even being wrong yet IMO,

T
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Re: Stumped - incessant cycling and pressures all out of wha

Postby jonathan_ed3 » Mon Mar 06, 2017 11:06 pm

So I got dismissed from my federal jury today pretty early (cool, because I was bracing for getting picked).

When I got home I put a rag in a vice grip and then clamped down onto the high side line after the drier and before the expansion valve. The high side pressure port I was using was between the compressor and this clamp.

I manually activated the clutch on the compressor and immediately pressure went to about 85, but to be fair, the static pressure was already nearly there as soon as I hooked up gauges originally. It's quite a bit hotter than it was the previous days messing with this.

After a few minutes of nothing happening I shut it down. high side pressure never went higher than maybe 90-95. It was about 85 degrees for the record at the time of the this test.

Then I dropped the car to the shop and had them evac. I left to go get the kids and in the meantime they started on another car. Unfortunately person A didn't talk to person B and tell them to make note of what they evacuated and then they started on another job before I got back. Kind of pissed, but the guy said he "thinks" it was over an ounce. I can't complain too much since it was free.

Who knows at this point how much was in there.

When I got the car home, I started taking the lines apart. The first thing I checked was the condenser. It flows free and has no blockages. Neither does the discharge line coming directly off of the compressor.

Then I got to the aluminum line between the drier and the condenser. This is the line we bent and relocated slightly.

I checked it like 20 times, and each time I checked with the air nozzle it seemed like there was no air coming out. Then I used a different air nozzle and finally I could feel air coming out. I was pretty ecstatic at this point because I thought I had found the problem (a blockage) before the high side service fitting. The problem is I never saw anything come out. It's just that I could finally feel the air coming through.

So now I'm questioning if it was really a blockage or not.

I'm thinking about putting it back together and vacuuming it down and trying to charge it again just for the hell of it.

Maybe there really was a blockage even though I never saw anything come out? Or perhaps I didn't have the nozzle in a good location to blow through the line? Even though I did it like 10 times. Who knows.

If there wasn't a blockage, does that mean the compressor is bad? Or was it really low on freon???

When I installed this second compressor, yes it was creating suction and pressure/exhaust when spinning the clutch. So I doubt it's bad. I still doubt the first one was bad at this point. I'm really just pretty sad about the whole deal. lol.
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Re: Stumped - incessant cycling and pressures all out of wha

Postby Tom Greenleaf » Mon Mar 06, 2017 11:47 pm

Take a break it's just a brain bender.

Too bad missed amount of refrigerant that came out.

Blockage? From what may not be known or much more about it. Unsure of making hoses, bending line if products (hose or line) can shard off of layer or what? Plain not sure. By rights made up line should have "barrier" hose and don't think that likes being pinched - not many hoses do well just from that though the idea is good.

Not complete and thinking about it some more. The pressure observed while hose pinched is still useless pressure if really stopped up air would spike better than that!

Tom
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Re: Stumped - incessant cycling and pressures all out of wha

Postby jonathan_ed3 » Tue Mar 07, 2017 2:31 am

so we evacuated the system, blew out every hose/hardline. Confirmed no blockages in any lines or in condenser etc.

Then we tested the manifold gauge set on my daily driver to rule out any gauge issues. They work, and they're accurate (was especially interested in the high side gauge).

Reinstalled everything and vacuumed, then recharged starting at 1 lb and went up to 21 ounces (the original Honda capacity). Basically stopped at 21 ounces because nothing was really changing pressure wise and we decided we're probably just wasting refrigerant (and we've wasted a LOT already through all of this) by continuing to fill.

We manually powered the a/c clutch to rule out any PCM overrides.

21 ounces in system. Clutch engaged FULL TIME, (manually jumped to bypass any PCM overrides), 80 degrees ambient, low side pressure continuously swung from 25-33PSI, and high side did EXACTLY THE SAME THING. 25-33PSI swing, together, in unison. It was about 75 degrees at the time.

Both gauges just kept swinging back and forth 25-33, 25-33, 25-33. With the clutch engaged full time! This correlates exactly with the pressure swing from the very beginning. The original youtube video has the exact same pressure swing when the clutch engages, although at the time we were letting the PCM control the clutch vs manually having it run full time now.

Suction line didn't get cold, discharge line didn't get hot, or even remotely warm.

So one of the running theories among the group of people helping try to figure this out is that perhaps the nozzle/orifice point inside the expansion valve is a little too big, therefore not allowing pressure to build. Okay, I can buy that. That would explain why the notion exists that these Camaro compressors don't work with expansion valves, even though dozens of Nissan 240sx, 240z, Mazda RX7 and various other hot rodders have made an LS1 compressor work with an expansion valve. It might not be "perfect", but it does work well enough.

However, in this case, I don't think the expansion valve is the problem...

Earlier today before pulling the system apart I completely pinched off the high side line with a vice grip wrapped in a rag and couldn't get the high side pressure to rise much more than ambient. And at the time the system had a higher charge than it did during this last test. Although not 100% scientific/accurate or possibly even safe, I know for a fact I pinched that line pretty darn good. At this point I don't care about the longevity of that line, I can always remake it if need be. Shouldn't high side pressure have skyrocketed as I continued to let the clutch run?

At this point I have to lean to defective compressor. For the SECOND time, from a DIFFERENT manufacturer. I cant fathom this as a possibility, but nothing else makes sense. RIDICULOUSLY low charge??? IDK.

It could be argued that the refrigerant charge could be low, but the fact that the suction and discharge are doing the exact same thing, in unison, points more towards a compressor issue than anything else. I'm just a novice, but nothing else makes sense.
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