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A/C rehab questions

A

apache

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I picked up a 85 Suburban and would sure like to get the air workin,its all there but it does nada when turned on. the compressor clutch dosent engage or anything.. I have 2 cans of R12 and thats it, is this enough for a recharge provided theres no leaks, and if the compressors shot and I have to go with a new one and convert to 134 what should this cost?
 
If it were me, I would see if there is any pressure in the system. It may just be low. Went through this with an '88 I owned.

You may have to jump the pressure switch temporarily to fill it.
 
In case you didn't know, if the pressure gets too low (from leaking) the low pressure switch keeps the clutch from engaging. Freon does not get used up. It leaks from the threaded fittings over the years.
 
you MUST have the front controls on first, before anything will happen with the rear A/C (as far as cooling)

rear A/C controls do not control the compressor.

when you turn the front system on, and then you hit the "fan" switch for the rear, if the fan doesn't turn on, you have other issues with power going to that fan, or a bad fan motor.
 
Keep in mind, if those are small cans ~16oz. or so, they will most likely not be enough for a dual system like that. My smaller system for the Safari calls for 42 oz for the dual system, unlike the smaller front only which requires around 28 oz or so.

As said above, you can quickly test the compressor by jumping the low pressure switch to ensure the compressor clutch is good. If the clutch engages, check the pressures to see if the system is just low. If it is just low, you can keep the switch jumped and add refrigerant to the system. Once you get one or two cans in, you should be able to connect the switch back up and see if the system will run.

If the system has no pressure when the switch is jumped, you will most likely find it is much cheaper to convert to R-134a than to try to find enough R-12 to charge the system.
 
A set of gauges is great, but for this, you can get by with one of those cheap single gauges from "Interdynamics" or something like that from your local car parts store. If you have no pressure in the system, you have to assume that air has leaked in you will have to fix the leak, vacuum the system down and then put in a full charge. That R12 only does you good if the system is just a little low.

If you have to do a full charge, you might think about selling that R12 to get some cash and convert to R134, since a full charge is a lot more than 2 cans. They haven't made R12 in years and I think it's over $100/lb now.
 
The stock A/C system in these trucks does NOT take well to R134a...especially the systems in the 'Burbs and even more especially with front and rear air. I've got a 1990 GMC 'Burban with front and rear air that I tried to convert to R134a a few years ago. It was a stupid waste of time and money. The thing wouldn't cool below 60 degrees at the vents. I wound up buying some R12 off eBay. System runs great with the R12.

If you are intent on converting you will need more than what the crappy universal kits have. You need good, heavy duty replacement fittings, new accumulator, new TXV for the rear unit, new orifice tube and a replacement condensor that is efficient with R134a. You'll need to flush the old mineral oil out of every line with solvent and use a compatible R134a oil. New o-rings will need to be installed as well that are compatible with the new refrigerant and oil. I believe your year 'Burban came with the A6 compressor which is a good unit. If the system is not compromised, you can probably flush the mineral oil out of it and reuse it. If your compressor is the A4, then it may need to be replaced...it's not a great compressor to begin with.

Anyhoo, as you can see, it's not that easy or cheap to convert. I'm not telling you this to scare you or anything, but I have seen people use enough of these universal conversion kits with very poor results (sometimes disastrous) and had to fix them that they are ahead to either keep on with R12 or do the conversion right the first time. If your system is clean and not damaged, you may be ahead to find some R12 and have it charged. However, the dual system does take upwards of 70 ounces of refrigerant...not inexpensive.

Kevin
 
I should have mentioned its only has front air and never had rear. Is the ow pressure switch the black 2 wire in line deal on the small line by the firewall?
Also today the shop I spoke with said R12 is still avaliable but no longer being made so the price will be high,if I need to convert they charge over $1000 to do it due to all the retro fitting of parts and a new compressor,also if somebody previously tried to use the now sold R12ice or something like this avaliable in AP stores which isnt really R12 it now has contaminated the system and NO repair shop will touch it because recovery will contaminate their equiptment with non this fake R12 crap and do a number on it. Guess I`ll try dumping in the 2 cans and see what happens,if that dont do the trick it time to lighten the load and rip it all out.
 
It sounds like your AC guy might be changing a bit much out for a conversion but without seeing the full list of parts I cant be sure. One thing I can tell you is that changing the compressor out is not required for a conversion (unless it is damaged).

They are correct about the "alternate refrigerants" Avoid them like the plague. only three things belong in an AC system. r134a or r12, oil of the proper type, and UV leak detector. That is it. No sealant, stop-leak or "enhancers" of any kind. They just cause grief.

A new "parallel flow" condenser (the part that sits in front of your radiator would make the r134A more efficient.

I can't totally agree with 4xcrazy on his comment. He is correct that it is a key item. His comment about all replacement units are r134a is not entirely accurate. The are all compatible including old ones but not all replacement condensers are high efficiency units. The key is parallel flow.

See this page for an excellent explanation of why a parallel flow condenser is better and how to identify them.
http://www.ackits.com/c/Parallel/Parallel+Flow+Condensers+-+Aluminum.html


I wrote up a post a while back on how to properly convert a system.

http://coloradok5.com/forums/showthread.php?t=235672

See post 20 for the details but the entire thread is enlightening.

I hope that helps your decision.

Cheers,
Rufus
 
I converted my 86 back @ '03 I think. I needed a new compressor and condenser to start with, so I converted it then.

I flushed out the system with a kit from j.c. whitney, intalled new dryer, o tube along with the c. & c.

It works just fine. Dark blue sub, N.C. summers, staying cool.....:D
 
rufusbooth said:
A new "parallel flow" condenser (the part that sits in front of your radiator would make the r134A more efficient.

I can't totally agree with 4xcrazy on his comment. He is correct that it is a key item. His comment about all replacement units are r134a is not entirely accurate. The are all compatible including old ones but not all replacement condensers are high efficiency units. The key is parallel flow

http://coloradok5.com/forums/showthread.php?t=235672
Click to expand...

guess i should have rephrased my comment, in saying that the new units MOST of us would buy at say a local parts store, will be considered 134a condensors, they ARE a different design than the factory r-12 unit,,, i say this because i replaced mine and compared the two.

the one i bought from the local parts store is damn near identical to the factory (134a) condensor in my '94 pick-up.

i have yet to test the efficiency of the new condensor, as during the installation process of the new freon, the compressor decided to die on me...
 
Thats a great write up on the conversion. A/C`s pretty much one of the mysteries of life to me so its foreign. Hopefully I can get it goin again the help here.
Thanks guys
 
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