92 chevy k1500 a/c conversion

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92 chevy k1500 a/c conversion

Postby stenny » Sun Jun 05, 2016 4:16 am

i am trying to convert my truck that is r12 to convert it to r134. i have never done this before so any help would be great. i already have the fittings and everything.
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Re: 92 chevy k1500 a/c conversion

Postby Tom Greenleaf » Sun Jun 05, 2016 1:30 pm

Welcome stenny:
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First off best to know what was the reason for loss or refrigerant as it was before considering this and was that all fixed. You said you have all needed for retrofit - parts, adaptors and so on.

Rubber products if original is IMO your choice now to save it they look real good and didn't leak. They are non Barrier hose but should be so saturated with oils now can hold the smaller molecule which makes up 134a.

Now the problems of exact charge and oil you have to pay attention to. I'll provide a very helpful link for charging procedures with a known system about ready to charge up and some things known to help first:

When, ready for charging and oil is thought correct either Ester based which is compatible in part with PAG oils or a total flush out and use PAG oil only. For GM suggest PAG 150 for this truck. That or drain out as much oil as you can and go Ester. Since you wont get all out do not add as much oil as the total system listed capacity which was 8oz. OK to be a couple oz over IMO but really can't know with a vehicle this old unless there's an exact history of work all along since new.

Important to know if you have the original condenser or not. Reason is its tougher but less efficient for 134a. Your call - I stayed with the originals as they were stronger physically. Any replacement no doubt was more efficient and lowered listed charge capacity. Hopefully something is written for any changes. OE charge of R-12 was about 44 oz. Charts can be wrong go by info under hood first always.

When time and holds a full vacuum start charge with as low as 65% of thought R-12 capacity. Give your calculator a work out. IMO again, no need to change the cycling switch on the accumulator as most if worked before are close enough for this now.

Can't know all equipment at your disposal so guess you'll vacuum down and charge by small cans or a 30 lbs tank measuring tare weight of amount the left into system. You'll get a fair amount into full vacuum without engine running at all. Enough for it to cycle and then finish to 65% or a touch more and stop there.

It should be blowing cool air, may still cycle too much but drive it around to get all oils moving and where they will settle the take all temp and pressure readings again and again along this procedure first time.

You can charge liquid for the first time engine off but suggest gas only to finish off while compressor is drawing in refrigerant. Pressure from source must be higher than the system so warm containers with warm water if needed - small can especially will go quite cold fast and be equal pressure and not release more.

Read, think, take all temp observations. Stop (this is my suggestion not all) when it blow cool and drive it. Don't hurry all this once some cooling is for real - this is to take every effort not to go over the perfect amount not to exceed 80% of known capacity.

Key note is more doesn't mean cooler. If you pass the mark system pressures will go up and cooling is less even with system then working harder - try not to let that happen.

Quite a read but worth it. Link here............

http://aircondition.com/tech/questions/ ... Procedures

Ask away if anything in that doesn't make sense to you and can offer help if you provide good info if not working out well.

Expect the BTU power of cooling to be adequate (trucks especially w small area to cool) to be about 80% of what R-12 new was capable of. Usually enough for most if all systems good especially noting power of fan clutch.

Good luck. Lots to observe while doing this and totally doable if you pay attention,

Tom
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Re: 92 chevy k1500 a/c conversion

Postby cornbinder89 » Sun Jun 05, 2016 2:05 pm

My advice differs slightly from Tom's. I would take a long hard look at the condenser. I have found that even if in great shape, the old tube and fin (with large 5/16 or 3/8" tubes) struggle to cool on 134a. If there is any doubt, replace it with either a serpentine or multi-path parallel flow type (not the OEM R-12 one) These newer types do a better job of getting the heat from the 134a into the air. It may take making new hoses to fit a generic replacement condenser, but the price and performance of going over to a new generic condenser vs. a new OEM type make it worth the work.
I've had a couple of systems that I have converted and were struggling to cool well enough, the problem was solved with a new condenser.
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Re: 92 chevy k1500 a/c conversion

Postby Tom Greenleaf » Sun Jun 05, 2016 2:12 pm

No argument with condensers. Just my luck that those old OE ones could take a shotgun blast and some new ones (aftermarket junk no doubt) first bug to hit one blew a hole in it so a bit more than disgusted! It is key to fastest and best performance no question,

T
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Re: 92 chevy k1500 a/c conversion

Postby cornbinder89 » Sun Jun 05, 2016 3:13 pm

I guess it is like everything else today. If someone make a good item, someone else will copy it and cheapen it to the point it doesn't function, just looks like the good component.
I use MEI sold thru the local Thermo-King franchise (Truck refrigeration dealer), among others. Recently went thru a sudden hail storm that dented the fins on both the radiator and condenser, but neither had damage to the tubes.
May be my experience on Semi's is clouding the issue. On those trucks airflow thru the radiator is top priority (which was why roof top condensers were common for a while) and condenser performance took a back seat to air flow. The large tube and widely space fins didn't work well when 134a replaced R12. In trucks, it is cheaper and easier to make the condenser bigger and have less fins, than it is to make the radiator bigger to handle the restriction of the condenser placed in front of it. They had the room to have very large single pass tubes and very widely spaced fins, to minimize the restriction to air flow, but they don't conduct the heat out of the 134a well.
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Re: 92 chevy k1500 a/c conversion

Postby MaxPF » Mon Jun 06, 2016 9:10 am

I have a 91 V1500 Blazer (full size), so I can chime in here. The OE condenser is useless for 134a, and the aftermarket units with small 6mm tubes are still crap. Either get a R134a parallel-flow type conversion condenser for your year, or a stock-type condenser from a, say, 1998 truck. The later condenser should fit in the earlier core support, but new hoses/lines may be needed.

Frankly, the worst part of that system is the R4 compressor. Reman R4's are worthless, and even the new ones aren't built to the standards of the original Harrison/Delphi R4's. Worse yet, the R4 was designed for R12 pressures, and the Scotch-yoke mechanism that drives the pistons was marginal with lower R12 pressures and mineral oil. Run higher R134a pressures and PAG oil and it's doomed from the day you charge it.


The best thing you can do is to fab or buy a conversion kit that lets you use a Sanden or Seltec ear-type compressor. I prefer Seltec TM16's, as I feel they are better compressors and they nearly match the R4 in displacement. If you want to run a Sanden, get the Enhanced SD7 (model# 4805) if you can find it, as it has more capacity vs the standard SD7H15. If you can't find it, the SD7H15 will work OK, but it may not cool quite as well at idle on a really hot day. Besides the adapter brackets, you will need new hoses and you will need to add a high pressure cutoff switch to the hot gas or liquid line since the generic Seltecs and Sandens do not have them integrally like the R4 does.

Here's the R4 that was originally in my truck:

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This is the Seltec mounted to the R4 bracket using some spacers/washers where needed:

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At some point I swapped a 6.2L diesel into my truck. The 6.2 had v-belts so I swapped the clutch on the Seltec to a v-belt clutch and, again with very minimal mods, mounted it to the original A6 bracket on the 6.2.

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As you can see, they are easy to adapt up to existing brackets. That along with their grater efficiency and longer life makes the conversion a no-brainer IMO. A Seltec TM16 and parallel flow condenser running 134a should be able to match the performance of your R4/tube-and-fin condenser combo running R12.
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Re: 92 chevy k1500 a/c conversion

Postby Tom Greenleaf » Mon Jun 06, 2016 12:56 pm

OP - Have you considered just leaving it R-12 and not have to mess with it at all except fix any leaks? It's still made new in non Complying countries plus mega tons of it left over new.

There's nothing that will beat it ever made for motor vehicles and no proof it either harms or doesn't harm anything. Only the hacks that drank the Kool-Aid bought into that lie. It was a corrupt change to make bucks like most things act before real proof never finished.

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Just search for it, it's out there,

T
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Re: 92 chevy k1500 a/c conversion

Postby cornbinder89 » Tue Jun 07, 2016 12:41 am

MAxPF, all good info. I use multi-path parallel flow "generic's" on all my conversions. You can get a larger capacity (BTU, TON however you want to measure) in a smaller footprint than the OEM design. Oversizeing the condenser a bit just about makes up any loses that 134a has over R12.
Never been a fan of the seltic or sanden, but would take them over an R-4 any day.
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Re: 92 chevy k1500 a/c conversion

Postby Nacho » Tue Jun 07, 2016 4:16 am

GMT 400's CK's convert quite well to R134a without replacing the condenser. We do replace the accumulator, orifice tube, reseal compressor, flush the system and add 700 grams of R134a. Excellent results.
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Re: 92 chevy k1500 a/c conversion

Postby Tom Greenleaf » Tue Jun 07, 2016 8:01 am

I'm just stuck on how cheap replacements are I guess. Can't or couldn't get OE again new on another brand vehicle and toss a new condenser in it every year once three holes in it from road debris.

Converted and do nothing else if old and good still they worked fine. If anything find the strongest fan clutch was totally enough.

Duly noted that where I am most side roads are in the shade and temps may be hot but not all day so systems don't work real hard for long. Park in the sun - takes longer to cool than R-12 but gets there.

It's mostly vehicles with highway use in Winters have the problem. Road debris is the road breaking up, broken plastic parts when super cold just snap off of cars, exhaust parts rust and fall off.

The whole game. Headlight lenses bust as well, some super costly.

Can't win this game if people must drive in that,

T
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Re: 92 chevy k1500 a/c conversion

Postby MaxPF » Tue Jun 07, 2016 9:06 am

Tom Greenleaf wrote:OP - Have you considered just leaving it R-12 and not have to mess with it at all except fix any leaks? It's still made new in non Complying countries plus mega tons of it left over new.

There's nothing that will beat it ever made for motor vehicles and no proof it either harms or doesn't harm anything. Only the hacks that drank the Kool-Aid bought into that lie. It was a corrupt change to make bucks like most things act before real proof never finished.

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Just search for it, it's out there,

T


Unfortunately, R12 runs about $30 per 12oz can, so you will end up spending 90-120 just on the gas. I got six 12oz cans of DuPont R134a for less than the cost of a single can of R12, or I can get a jug of DuPont 134a for less than the cost of 4 cans of R12.
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Re: 92 chevy k1500 a/c conversion

Postby MaxPF » Tue Jun 07, 2016 9:17 am

cornbinder89 wrote:MAxPF, all good info. I use multi-path parallel flow "generic's" on all my conversions. You can get a larger capacity (BTU, TON however you want to measure) in a smaller footprint than the OEM design. Oversizeing the condenser a bit just about makes up any loses that 134a has over R12.
Never been a fan of the seltic or sanden, but would take them over an R-4 any day.


What don't you like about the Seltec and Sandens? Granted I prefer the Seltec over the Sanden, but both give long life is the system is put together clean.
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Re: 92 chevy k1500 a/c conversion

Postby MaxPF » Tue Jun 07, 2016 9:22 am

Nacho wrote:GMT 400's CK's convert quite well to R134a without replacing the condenser. We do replace the accumulator, orifice tube, reseal compressor, flush the system and add 700 grams of R134a. Excellent results.


My experience certainly differs from yours. Granted, the GMT400s cool better with a simple conversion vs the OBS trucks like mine, but they still aren't very good compared to the performance with a parallel flow condenser. I figure since the condenser needs to be flushed anyway and replacement parallel flow units are fairly cheap, why not upgrade?
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Re: 92 chevy k1500 a/c conversion

Postby cornbinder89 » Wed Jun 08, 2016 2:19 am

RE: seltec and Sanden, When they 1st came out, they didn't seam to last, by the time the front seal needed replacing the compressor was shot. Pulled a whole bunch of seized ones off trucks. Replaced more of those than all the rest combined, so it left a bad taste in my mouth for them. I think they must have improved since then. I like steel or cast iron over aluminum for parts that wear.
For my money, its hard to beat the A-6 Delco, if you keep oil in it they last, they also have a high capacity (42K BTU IIRC) than most others out on the market. Main drawback is size and weight.
I once saw a motor coach that had the big 4 cyl sutrac compressor replaced with 4 A-6's in a frame. Cooled the whole coach and the shop said it cost about 1/10th what it would have to replace the Sutrac.
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Re: 92 chevy k1500 a/c conversion

Postby stenny » Thu Jun 09, 2016 5:36 pm

ok so i vac out old stuff and i put in the new r134a first i put in the oil can then the other cans and i guess i didn't put enough in because a/c light was blinking so i filled it a little more, disconnected battery ran it it was a little cold then i drove it and about 20 min a/c light was blinking again i checked level it was good still. so i think pressure switch is messed up because ac compressor won't stay engaged. i haven't messed with it since then. i saw there is a wire you can cut which will make it so the ac compressor pressure switch won't make system disengage. i am gonna try to by pass pressure switch see if compressor stays engaged or just replace pressure switch. i am not trying to replace components because i am gonna be doing a cummins 4bt swap in this truck soon and idk if i can get a ac compressor etc for the motor or if i can adapt my ac compressor to the cummins so i don't want to blow a bunch of money just for ac to work for a shortt time
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Re: 92 chevy k1500 a/c conversion

Postby Tom Greenleaf » Thu Jun 09, 2016 6:57 pm

How much did you put in, in total? You have to know that not just blast it in. Pressures don't tell you it's full or enough at all and if not engaged it's only telling you static pressure which is usually close to the temperature in F. which only means you have at least a couple ounces in the system. Bet it all leaked out right away and that's the problem you fix first not after when possible,

T
PS: You don't have to guess a pressure switch just test light power comes in and gets sent out - that's all it does......
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Re: 92 chevy k1500 a/c conversion

Postby stenny » Thu Jun 09, 2016 9:36 pm

I just used the gauge it didnt take a lot
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Re: 92 chevy k1500 a/c conversion

Postby stenny » Thu Jun 09, 2016 9:38 pm

8 oz pag oil with r134. And a 12oz bottle and it was reading full on my gauge. So i didnt want to overfill and go into the red on the gauge
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Re: 92 chevy k1500 a/c conversion

Postby Tom Greenleaf » Thu Jun 09, 2016 10:29 pm

?? GAUGES DO NOT SHOW HOW MUCH OF ANYTHING YOU HAVE IN A SYSTEM - EVER. They show pressures and can indicate problems or that's it's ok if performance is ok - none seems to be.

8oz or PAG oil. Fine but that's for the whole system from bone dry. If you added that with any OE mineral oil in it you need to flush the whole thing out and start over soon.

PAG requires as they all do enough charge of refrigerant to move it along to lube compressor within a minute or so or you risk burning it out right away.

Compressor should cycle on this with ONE 12oz can is plenty for pressure for a LPCO switch to cycle and would pull in the remaining charge which will be unknown with a conversion so you start low as already said.

If you didn't flush out all mineral oil and chose PAG anything they are not compatible so really can't think of anything but starting over and what's in there is just a hazmat now.

Did you read anything from the "Knowledge Base" up top and one I posted? Apparently not.

>> http://aircondition.com/tech/questions/ ... Procedures << That alone is for charging an empty system known ready to be charged. Other info in that section expounds on conversions with opinions that can vary. I prefer Ester oil, other don't - things like that.

Again, if mixed or didn't flush out mineral oil start over. IF you did then if compressor isn't pulling in more refrigerant you can jump a two wire LPCO carefully and only for the time to charge then put it back as the safeguard it is,

T
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Re: 92 chevy k1500 a/c conversion

Postby cornbinder89 » Thu Jun 09, 2016 11:04 pm

stenny wrote:8 oz pag oil with r134. And a 12oz bottle and it was reading full on my gauge. So i didnt want to overfill and go into the red on the gauge

I take it from this, you are using one of those "kits" with a can and a gauge on it? If so you really need to invest in a manifold with high and low pressure gauges to do any kind of A/C work. Those "kit" gauge tell you almost nothing about what is happening, and often they are way off on pressure.
I advise against cutting any wires.
As Tom said, go back and clear out any mineral oil and start from square one, with new pag in freshly flushed hoses evap, and condenser. new accumulator and proper oil fill in compressor. It really is the only way.
Pressure only equates to temp, so can be used as a guide to how well the system is working but not to amount of refrigerant in the system. They are two different things.
Those "kits" that are sold can work, but only if there was nothing wrong with the system before you start. So if a hose is leaking, you need to know and fix that first. If a hose burst, you need to know why, and fix that first. Then you can add the correct amount after vacuuming and oil checks.
I must confess, I keep one of those quick-kits in my side box on my semi. I travel with a dog, and it can get so hot if something fails on the road, to kill a dog. I'll risk an a/c system meltdown to keep my dog alive. I haven't needed to use it, but I have it. They are no "cheap replacement" for a set of gauges and manifold.
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