HELP!!!!!

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HELP!!!!!

Postby scott may » Sat Sep 03, 2016 9:58 pm

I am at a loss with the weirdness i am experiancing. Ac in wifes jeep liberty stopped blowing cold so i investigated and noticed the pressures in high and low side were quite high 70 on low 350 on high so i figure freon is cheap so i evac the system and vac it down for about 45 min. so then i go to refill the system and get about 6oz in system and compressor is running nonstop pressures are 60 ls and 300+hs i have no idea what is causing this any ideas? 2004 jeep liberty whole ac system minus evap and cond were replaced 2 years ago any help is appreciated thanks in advance
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Re: HELP!!!!!

Postby Tom Greenleaf » Sat Sep 03, 2016 10:49 pm

? Are you charging this thru gauges and from what type of source?
You do mean pressures in PSI don't you?

If you can really believe those pressure readings with just 6oz in the system something is all wrong.

That amount would or probably just show static pressures and if compressor engaged a vacuum low side reading and about nothing much for a high reading.

Equipment or something is all wrong or I don't understand what methods you are using with what equipment,

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Re: HELP!!!!!

Postby scott may » Sat Sep 03, 2016 10:58 pm

12oz cans through manifold like i said it's really weird compressor kicked on almost instantly when i started adding liquid charge
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Re: HELP!!!!!

Postby scott may » Sat Sep 03, 2016 11:03 pm

i actually went and bought new manifold set because i thought something hinkey with my old set... nope same readings
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Re: HELP!!!!!

Postby cornbinder89 » Sat Sep 03, 2016 11:38 pm

1st, when you vacuum it down, are both the high and low side valves on the manifold open? Are you seeing a vacuum on the high side.
I just can't see how you are getting those pressures with only 6 oz of refrigerant. A plugged system might show that on the high side with 6 oz but then the low side would be low.
Are you sure of your gauges accuracy?
A system full of non condensable (air) that is then had 6oz of refrigerant might see those pressures, but not an empty system with only 6 oz in it.
I am at a loss to explain it, something doesn't add up.
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Re: HELP!!!!!

Postby scott may » Sat Sep 03, 2016 11:47 pm

i have about 30 years exp working on cars mostly muscle cars and 4x4 but i have never seen anything like this 2 dif manifold sets one new one old both decent quality show same thing both sides were open to vac its crazy and not adding up thats why i'm here totally baffled and clueless it makes no sense but its whats going on btw i even evac the system a second time and vac down using same can of freon b4 can was empty did same thing again
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Re: HELP!!!!!

Postby Tom Greenleaf » Sun Sep 04, 2016 12:08 am

Sorry for delay in your post - site is screwy sometimes!

You really need to know each manifold set. Knobs for each H+L and check valves another on lines or ends just lock gas, seal and read pressures.

When a manifold gauge set has both attached and if high side is not properly shut off the two can mix, pass each other on some.

I can't describe every set made - My current just two sets are very similar in behavior. So, if can tapping with a loooong yellow hose it may also have a check valve - can't know this stuff for each.

What is wrong is it makes no sense yet. Some A/C designs will run on just some pressure for a grace period some wait for real pressure or will not engage - each vehicle can be different.

IDK - I think there's something wrong with how you are connected and which knob is where as part of the readings basically being impossible.

If you used the same set for vacuum it might have only read vacuum of the set not the system.

I just can't know why this is reading these pressures yet at all. Must just be reading pressure of the source can but it would have to be HOT to read a high pressure?

In the meantime, don't allow compressor to run too long until you figure out why the crazy readings. It can't run if really low for long without harming the compressor as oil isn't moving till it can condense the refrigerant and begin to flow the full circle properly,

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Re: HELP!!!!!

Postby Tom Greenleaf » Sun Sep 04, 2016 12:12 am

Have to add in a new post as it showed you were on line in my view.

Don't go jumping any switches on a Mopar especially to force compressor to run!!!!! If you add power just the wrong way you'll blow the engine control computer and really not be pleased!

A system under real full vacuum should just about take those 12oz cans, one if warm in hands even, liquid fine and engine off. Then it should allow compressor - not before I'm pretty sure,

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Re: HELP!!!!!

Postby ACProf » Sun Sep 04, 2016 7:06 am

12oz cans through manifold like i said it's really weird compressor kicked on almost instantly when i started adding liquid charge


This statement really bother me!
Does this mean you were charging an empty system with LIQUID with the A/C On and the engine running?
Good way to ruin a compressor and put metal shavings throughout the system.
No oil circulation to lube the compressor when the system has no refrigerant charge.
Also You slug the compressor inlet with liquid and freeze damage the port valves. NEVER charge liquid into any running system.

DO you have the HIGHSIDE MANIFOLD VALVE open with the A/C unit running. If you port that much pressure back into the 12 oz can you'll find out the can can't hold that much pressure!
Make sure you are wearing eye protection when charging the A/C. It's hard to get your eyes replaced after a relief valve or hose fitting sprays refrigerant in your face!!!

Could be your condenser inlet (or some spot further down the high side line) is completely plugged and going nowhere. But the really high side pressure is bleeding back through the compressor high side to the low side.

P.S. Its NOT your gauges.
Good luck!
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Re: HELP!!!!!

Postby scott may » Sun Sep 04, 2016 7:19 am

all valves open during vac hs valve on line open valve on hs manifold closed when running both valves on ls open no pressure switch is jumped i never do that it's silly and dangerous comp will kick in when pressure is high enough this one is turning on almost instantly with liquid add and staying running once about half a can is in system pressures jump up suddenly from 25 30psi ls/150 175 hs its 85 degrees outside i am in ne fl proper charge is 1.37lb of 134a i have lots of experience with ac done 100s of vac and charges over the years this is so crazy i'm at a loss to where to go now its almost like i have multiple issues bad pressure switch letting comp run and pressure bleedover from hs to low and system somehow clogged on both sides letting such a small bit of freon pressurize it engine off hs open ls closed add freon it will only take a tiny bit b4 no movement in sight glass close hs manifold valve start engine ac on compressor not running yet add freon to ls comp comes on almost immediately went out after dinner and was playing with laser thermometer while it was running hs temps at port 170 180 ls temps at post 130 150 something really screwy is going on
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Re: HELP!!!!!

Postby Tom Greenleaf » Sun Sep 04, 2016 11:40 am

Scott: Just some notes as this is suspect of real damage now IMO.

Chrysler (I still call them Mopars) designs are on their own. I quite likely has the grace period to enable engagement of compressor if empty or a vacuum long enough to wreck it which isn't long.

Now I'm thinking with liquid charge as ACProf brought up you've slugged compressor as engine was running. Not a good idea especially if placement of port is close to compressor. Better and faster with liquid w engine OFF into a vacuum it would be vapor for first little can.

So if compressor didn't just lock or squeal belt over it chance of debris from choking then lack of oil is high.

Your temp observations with so little refrigerant in it (if still that low) are probably just heat of friction on very little refrigerant would also give you pressures.

Just FYI: You don't need to vacuum both sides - it's one system. IDK if knobs on gauges not in correct position you may have added refrigerant (best for most if you quit using the word Freon as that still suggests another refrigerant not 134a.)

Condenser could clog tight with debris and compressor allow backward flow of gas and odd pressures or temps.

These vehicles best charged without engine running at all with equipment that puts in specified charge exactly before starting engine at all not drawing it in thru low side counting on compressor.

This method of charging is becoming very risky and out of date. High side ports have been increasingly eliminated as the switch is sensing the pressure sending info back to computer controlled A/C in these and many other models as well. No need for it have a port.

IDK - a problem with the little cans is how quickly they go cold and equal pressure of the system so must be kept warm as pressures will by plain physics of it will travel from higher to lower.

As already said all caution with those as the burst pressure IMO is very uncertain,

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Re: HELP!!!!!

Postby cornbinder89 » Sun Sep 04, 2016 5:31 pm

Tom, The reason I asked about opening both valves was I was trying to determine if the system was plugged and 1/2 was not evacuated, and that was causing the high pressure reading. Opening both also draws the system down quicker.
Liquid charge should be done thru the high side with the engine off, no chance of slugging the compressor that way.
High side reading are inportant, you need to know what the condensing temp of the system is to asses the heat transfer in the condenser.
My guess is mfg are dumbing down the systems by eliminateing high side pressure ports. "make it safer for idiots" rather than make it serviceable.
I guess I'm damn tired of mfg makeing things un-serviceable because of people who don't realize that there are things that can hurt or kill you.
Pressure readings are the most accurate way of telling what is happening inside a closed system, non contact and contact thermometers only indirectly measure what is taking place inside.
Not having a high side port keeps Joe idiot from connecting a small can to it and having it burst in his face, blinding him, but removes needed info that can not be replaced by micro-processors. They can not tell if the sensor or system is out of wack, only that the reading fed to it is out of spec.
Last edited by cornbinder89 on Sun Sep 04, 2016 5:39 pm, edited 1 time in total.
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Re: HELP!!!!!

Postby scott may » Sun Sep 04, 2016 5:37 pm

so it looks like i will be ordering a whole new ac system for the third time in 5 years i guess this time i will be replacing evap and condenser and all lines since there is obviously a an issue with one of those because everything else has been replaced several times now
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Re: HELP!!!!!

Postby cornbinder89 » Sun Sep 04, 2016 5:45 pm

I would be spending more time on figuring out where the problem lies. Condensers can be tricky esp if they have parallel paths. they can flow some but not enough. If I was going to throw parts at it, I would start here.
If the evaporator worked at one time, I would be loathed to replace it due the work involved.
Lines can be removed and flushed or checked for blockages.
Remember, pressure is just the lack of flow, so something must be restricting the movement of refrigerant.
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Re: HELP!!!!!

Postby Tom Greenleaf » Sun Sep 04, 2016 6:26 pm

I can't be 100% sure of diddle on the web vs checking this out in person. If this has become a routine to ruin systems what is someone doing? It might be just bad luck.

I'd send this out for a diagnosis only which very well may mean charging it up or IDK what to check and estimate what it will take to make this work properly. Not fix it but list out what items and things are needed now and decide if this is for you or not from there.

The only thing notes many times on several Chrysler vehicles is evaporators are too common? Why IDK. Would think a second wouldn't leak which the first ones did.

Seems troubles since forever mostly begin with a leak and system keeps running rather than shut down early enough to save itself.

IDK - like running an engine with no oil pressure why with technology do any keep running when it's down to seconds before engine is going to seize up anyway.

Good grief - on a rant I guess but have a probably 40 year old back up generator (portable electricity thing) that shuts down if oil is low so don't get when designs don't do the same for A/C which almost never is just the low charge but the lack of lubrication from low charge and still compressing away sounding like marbles are in it.

I'm just not very conclusive for you on why you are getting such results with any certainty.


These vehicles in particular as I think mentioned before you really should consider getting them ready for a shop to do the final charge that can push in charge by exact spec and avoid a lot of risks,

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