Anyone experienced this...

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87ChevyR10

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So, I am getting quotes for the AC system. The compressor needs replacing. I just got off the phone with Meineke and was told they may not be able to do the work. Guy said the older R12 systems (mines converted to R34) uses a different amount than current R34 systems.

So, is this how thing are going to be with older vehicles? Deny enough services to have to do them yourself or go buy a newer vehicle? Heck, Walmart denied me oil change service today because I use the ACDelco PF454 filter due to long tube headers. Never been an issue in the past.

Also, does anyone know how to tell if the clutch bearing is shot or the whole compressor?
 

1987 GMC Jimmy

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Ahh, that's ********. Yeah, they use different amounts, but you have to put the corresponding amount of R134a. I have it written down on my conversion sticker, but you charge it with x% of the original capacity. That guy at Meineke can stick it where the sun don't shine. I wouldn't bother trying to rebuild that Harrison/Delphi R4 compressor. I'd get a new one (not rebuilt), and I think O'Reilly and RockAuto are neck and neck as far as cheapness goes. The textbook way to go about it is to evacuate, remove the compressor, probably go ahead and replace the accumulator/orifice tube, install the compressor, pull vacuum to make sure it holds, and charge to spec with a mix of freon and PAG oil. I think a new one will be pre-oiled, but make sure there aren't special instructions.
 

1987 GMC Jimmy

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You'll need the tool you posted, and you can borrow a set of manifold gauges from Autozone.
 

yevgenievich

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Autozone rents all the tools that are needed. Oreily starting to do so too
 

87ChevyR10

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I've seen some pics about R12 to R134a conversions. Is the amount used based on current ambient temp and humidity? I've also read where the OEM hoses are not up to par for use with R134a and can leak it. Also, that HF pump I posted, will I need to do both hi and low sides or just the low side for evacuation? Which side do I use for refilling?
 

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When I switched my '79 to R134, I changed all the o-rings in the system (make sure to put a little oil on them) and I charged it to 80-85% of the R12 system. The other thing I did was change the orifice tube to an adjustible one. I had read it was better for 134a systems.
 

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smoothandlow84

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Meineke....ya they're a bunch of mis-informed and underqualified asshats. Its easy enough to do the swap yourself.


Buy the new compressor from Autozone, get the lifetime warranty.....which require a new oriface tube, accumulator and hoses in order to qualify for the warranty. Evacuate the system, pull a vacuum, add approximately 4 cans of r134a and some pag oil...check for leaks. Easy!


I replaced all of my ac components...all new from Autozone with the lifetime warranty on the compressor. Meineke, jiffy lube, are both a bunch over overpriced and lazy morons. Recharging the system isnt rocket science, they just make it sound like it is in order to justify what they get away with charging. Do a search on your local craigslist.org to source some r134a. I was able to buy a case of r134a from an ac contractor and paid $5 per can. Also a good idea to pick up some r134a/system sealant from Autozone just in case there is a miniscule leak in the system. It seals well and is simple to use as well.
 

smoothandlow84

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I've seen some pics about R12 to R134a conversions. Is the amount used based on current ambient temp and humidity? I've also read where the OEM hoses are not up to par for use with R134a and can leak it. Also, that HF pump I posted, will I need to do both hi and low sides or just the low side for evacuation? Which side do I use for refilling?
The gauges only allow you to connect to one side of the system. The connection is at the accumulator tank. You may also need to swap out that fitting if it is still an r12 setup. R134a has a different male fitting connection needed to charge the system.


Btw...all of my new ac components were about $325...compressor, hoses, accumulator, oriface tube and r134a
 

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I've seen some pics about R12 to R134a conversions. Is the amount used based on current ambient temp and humidity? I've also read where the OEM hoses are not up to par for use with R134a and can leak it. Also, that HF pump I posted, will I need to do both hi and low sides or just the low side for evacuation? Which side do I use for refilling?


Couple of notes:

No component changes are required to switch over from R12 to 134a. All the currently installed parts can remain and will work just fine with a 134a charge. You might want to change to replace the Accumulator (filter drier) and the expansion tube. The accumulator/filter-drier is that big silver canister attached to the evaporator housing. The expansion tube is accessible by opening the fitting that connects the liquid line to the evaporator inlet.

You will have to dump any remaining R12 before anything else is done. You can legally release it to atmosphere, but certified shops cannot.

They have special re-re (refrigerant recovery) equipment that captures the R12. When they have a full bottle it gets sold to a facility that purifies and repackages it for re-sale. The production of new R-12 was banned worldwide years ago, so the only source is what can be reclaimed.

Anyway, if a shop does this conversion, that recovery process will trigger an extra charge. If you do it yourself it is free.

Whatever way you do it, after the refrigerant gets dumped, the system will need to be flushed, evacuated and recharged with 134a.

Flushing is required because the oil used with R-12 is non-compatible with the oil used with 134a. There is a specific, involved, expensive way to do this - or there is the easy way. Provided your system is not being changed over due to a "black death" casualty you can do it with all the components in place and using just compressed air.

Black death is just a term used to describe a refrigeration system that has been disabled due to a catastrophic failure of the compressor. All the components and connecting tubing/hoses are contaminated with burnt (caked on) oil and all the metal particles that resulted from the compressor failure.

Release all the tubing fittings that connect the 3 main components (compressor, condenser & evaporator). Remove the suction/discharge hose manifold from the back of the compressor. Release the discharge hose from the condenser inlet and the suction hose from the accumulator (filter/drier) outlet. Pull the existing expansion tube from the tubing that leads into the evap. Remove the accumulator/filter-drier.

Using 100 psi compressed air at a good volume:

Blow the residual oil from the condenser and evaporator coils. Do this in in both directions. Repeat until you feel that the bulk of the old oil is removed.

Blow out the liquid line that connects the condenser to the evaporator.

Blow out both compressor hoses.


Understand that the old R-12 oil is not like "poison" to the newly added 134a - it just does not circulate as well. So if there is a bit that remains in the system it will not be an issue.

That's it for flushing.

Using new o-rings at the fittings, replace your filter drier and expansion tubing.

Add PAG 100 oil in quantities as below and close the system up.

•Compressor- (1 ounce)
•Evaporator - (3 ounces)
•Condenser - (1 ounce)
•Accumulator (2 ounces)

Evacuate, leak check (system should hold 28" Hg overnight) and charge with about 50 ounces (4 cans) of 134a. You will have to jump your low pressure cut-out switch to get the first 2 cans in. After that the system will have enough pressure to allow the low pressure switch to operate normally and keep the compressor running.

You will need to buy a set of adapters for the service ports so you can charge and attach your gauges - if you have them. The adapters just screw onto the existing service ports.

Here is how the refrigerant charge for 134a is determined:

When an R-12 system is retrofitted to 134a, the general rule of thumb is that the refrigerant capacity/charge should be reduced to 80-90 % of the original capacity.

The original GM spec for these trucks was 56 ounces of R-12. So, if we take 56 ounces of R-12 and multiply it by .85, we get a 134a charge of 48 ounces.




From GM:

R 134A Retrofit Procedures

UPDATED BY TSB # 331226 DATED JANUARY, 1994

Retrofitting an R-12 vehicle to R-134a requires careful preparation to insure that neither the vehicle nor the A/C service equipment has become contaminated.
When performed properly, the retrofit from R-12 to R-134a will have minimal effect on the system's performance in most climatic conditions found in the United States and Canada.
COMPRESSORS DO NOT NEED TO BE REPLACED AS PART OF THE NORMAL RETROFIT. An R-12 compressor that is operating properly can be left in the vehicle when it is retrofitted to R-134a.
 

chengny

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Also, does anyone know how to tell if the clutch bearing is shot or the whole compressor?

An easy way is to check whether the compressor is still functional is to engage the clutch with an external power source. When it is pulled in, just try to roll the rotating assembly over by the belt. It might not tell you if it's perfect, but - if it cannot be easily rotated - that will tell you if it is shot.
 

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I guess it was missed in an earlier post that my system has already been converted to R134a.
 

87ChevyR10

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Also, does anyone know how to tell if the clutch bearing is shot or the whole compressor?

An easy way is to check whether the compressor is still functional is to engage the clutch with an external power source. When it is pulled in, just try to roll the rotating assembly over by the belt. It might not tell you if it's perfect, but - if it cannot be easily rotated - that will tell you if it is shot.

I had to unplug the compressor because as soon as I turned it on, the belt would squeal LOUDLY. The AC pulley does not turn once the clutch is engaged.
 

chengny

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I had to unplug the compressor because as soon as I turned it on, the belt would squeal LOUDLY. The AC pulley does not turn once the clutch is engaged.

There is your answer.
 

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