I bought an 85 a year ago. The A/C has never worked. I assumed it was too low on freon so the compressor won't come on. I want to redo all the seals, flush, and convert to 134a. And now I just learned you can't flush the compressor!
My plan is to add some 134a to see if compressor will come on. If so, and it does sound bad, start flushing the system. My question is if I can't flush the compressor, how do I know to add oil? How do you clean compressor?

 

It is not a serious concern. For this conversion the proper oil to use is ester. The old R12 used mineral oil and the R134A uses PAG oil. Ester is used because it is compatible with both mineral and PAG. Remove the compressor and drain the existing oil. Refill with ester, hand rotate the compressor and drain again. Refill with the proper amount and Bob's you're uncle.

 

Any way to drain oil without removing g the compressor? It looks like removing the compressor is not an easy job. Is the oil added thru the refrigerant holes in the back of compressor?

 

I went through this on my 85 and R134a conversion by the book. you'll need a new accumulator(dryer) and maybe a new compressor. in addition to the new components (compressor, accumulator(dryer)), I bought a flush kit to clean and flush the evaporator, condenser, hoses, and high pressure tube. I did swap out the low pressure cycling switch and from the standard .072 orifice tube to a .067 assembly. you will also want to replace all O-rings, and get the 134a service adapters. I used ester oil in my system instead of PAG150. once I got my o-ring sizes sorted, everything went together without issues. pulled a system vacuum for about 4 hours, and added 36oz of R134a - high and low pressures within spec, and my center dash temp around 59° w/ outside temp of 92°. according to the chart, pressures and temps right on the money. a great source of info, literature, parts, and material is FJC. get a copy of the conversion manual - everything you need to know --


when everything was sorted, my center duct temp was around 40F degrees. seven years now - no problems or issues. basic flush kit -- FJC R12 to R134a Retrofit Kit - FJC2530 - Penn Tool Co., Inc . BTW, bought a new AC Delco compressor and dryer from rockauto. as i recall, the 85 will take 8oz oil. you'll need to break it down to 2oz quantities add it in four different locations (condenser, accumulator hose assembly, and compressor) after you clean and flush the system. while you have things apart, and you want to go to the next level, you can modify the compressor mounting bracket so the one bolt that comes in from the rear now installs from the front. makes compressor service a simple task -- need some help - 1985 AC compressor mounting modification - CorvetteForum - Chevrolet Corvette Forum Discussion

 

If the system is already empty, there is a crude way to test the compressor clutch. You can fill the system with compressed air to verify the operation of the pressure cycling switch and the clutch. I do not recommend doing this with the engine running nor do I recommend leaving the air in there long. Have a vacuum pump ready to evacuate the air (and its moisture).

Also, while pressurized, you have a good opportunity to spray soapy water all over the system and inspect for any major leaks.

Its cheap, easy, and doesn't involve freon.

 

THANKS FOR ALL THE INPUT EVERYONE! NEW TO A/C!

Compressor looks to have failed based on the oil visible on the belt tensioner, compressor and AC lines in line with the belt. Buying new Compressor. Didn't try to pressurize as I assume it would just leak out from compressor.
Questions:
1. Plan on buying AC Delco gold compressor and dryer. Any concerns??? Better brands?
2. Can I flush the system days before assembly as compressor would not be delivered by the weekend. I wanted to flush this weekend because I have access to compressor that would dry/blow out the flush (80psi for 30-45 minutes). I believe it would be close to a week between flush an and assembly. I didn't know if this would matter since I'm using compressed air to blow out all the flush anyways. Plan would be to put caps over opening to prevent any dirt from getting. After compressor arrives I would pull vacuum for 30-60 minutes or until moisture gauge on shows none in the system.
3. Is it possible to reuse the lines if the system holds a vacuum? Would they need flushed being form an R12 system?
4. What valves would you automatically replace? High pressure cut off valve?

 

Flushing the lines before hand and sealing them is acceptable if you remove the old compressor so as not to circulate any oil. I want to point out one thing you may not have considered. What type of system are you ordering the new compressor for? If you order one that matches your old one, you need to insure it is for R134A and not R12. The majority of replacement compressors come prefilled with oil. If you order one that is for R12, it will have mineral oil and that is not compatible with R134A.

 

I assume, given R12 is no longer used, they were all for R134A. I found the same compressor (part# match) on Rock Auto and the specifications say Compatible Refrigerant Oil Type is PAG 150. I believe that is the oil for R134A. I'll have to wait until Saturday to find out (new delivery date). If it is prefilled with mineral oil - would you screw trying to drain and flush out the compressor with PAG 150 or just buy one that comes with PAG150?
I definitely want to flush even if I don't have all the parts. I was thinking I would be able to remove the lines to flush and just cap/seal back of compressor to be able to drive the car, sound reasonable? I would love to reuse the lines as well if possible.

 

If it says on Rockauto that it has PAG oil, then I would assume it does. It should come with a tag or leaflet explaining what is in it for oil. You make no mention of cleaning the condenser and evaporator. These would also have mineral oil in them. What are your intentions? Also, what are you using to flush?

 

I definitely plan on reverse flushing both the evaporator and the condenser, both of them twice to make sure. Do I need to flush the AC lines as well? I wouldn't think it could hurt. I need to figure out the flush. FJC Refregerant flush from amazon sound good?.

Compressor i bought was

ACDelco Gold 15-21638 Air Conditioning Compressor

 

You wouldnt happen to have a low pressure switch part number?

 

Just a note that I believe from all I've read that you can't really effectively flush the condenser - the lines are too small. Better to replace if there's contamination in there.

I recently got an RY or R&Y compressor for my 1989 Vette. It came prefilled with pag oil - but there was no documentation or info on the web on the type.

I had to find out from the company directly - turns out it is pag 46 for me. I just couldn't believe they didn't provide the info anywhere.

 

Well the GM compressor was delivered yesterday. Read the instructions (from 4 seasons) and th3. Oppressor has a pink tag referencing g it has 3 oz of Pag oil in it. Nothing specific concerning the Pag oil though. I need to call them.
I have decided to replace the water pump (original) and the tensioner bearings as well. I plan to put a high flow water pump in it. My daughter knows how to drag the RMPs and get it hot.

 

Well I have the compressor lines but waiting on low pressure line and waterpump to be delivered to kick into the conversion. Today I pressurized the system with compressed air to adjust the lower pressure cutoff switch to 21 lbs. I had to pressurize syatem to 58lbs before the switch would show continuity. Continuity would continue until I lessened pressure to 21lbs. I would then have to pressurize to 57-58lbs to get the switch to close again. That doesn't seem right. I would have thought once the pressure exceeded 21lbs ot would close (have continuity). Should I replace the switch?

Also, I bypassed the low and high pressure switches and got the compressor to cycle. The lead wires showed 11.7 volts at the compressor. However, the condensor fan never came on, even when I bypassed the switch on the high pressure line. How to test what the issue is? I would like to have this resolved before bolting up the new compressor and lines. Is there a relay I need to test?

 

So, a couple of things here. Where would you ever get the idea to pump your system full of moisture laden air? Nothing should be used to pressurize but refrigerant or nitrogen. For the cycling switch, it needs to have a differential. You say - " I would have thought once the pressure exceeded 21lbs ot would close..." If that were the case, it would be slamming in and out like a woodpecker on a diseased oak. The high pressure does not need to be bypassed because it is, by default, a normally closed switch.

 

I only used compressed air as I'm going to be installing a new compressor, new dryer, lines, shrader valve, and o-rings. I will be flushing both the evaporator and condensor extensively. I don't beleive this system has been operational for years. I do t have any access to nitrogen ( that I'm aware of).
The differential makes sense- sounds like I don't need to change it.

 

I bought the book. Says to use the .067 orifice tube but no part number.

 

as i remember, they are universal and color coded. the .067 tubes are blue and commonalty used in ford products. sold at most auto parts outlets. google ".067 orifice tube"

 

I found Carquest brand but not Motorcraft or any other brand.