AC Help Needed. AC experts appreciated (Page 1/2)
sjmaye AUG 13, 01:32 PM
I pretty certain I have a leak. Just don't know where or how big.

A little background. When restoring the car back in 2008 I replaced the compressor and did all the things to change to R134A. I evacuated the system and then charged it. All that went OK as I recall. Maybe 1 or 2 years later I recall I no longer had cold air coming out. At this point I drove the car maybe 10 miles a year so I forgot about it.

Fast forward to 2020. I wanted cold air so I could drive the car throughout the summer. I started the car and turned on the AC blower on high. Fans up front turned on, but the compressor clutch did not kick in. I figured it was so low on freon the low pressure switch was not letting the compressor come on. I bypassed the pressure cycling switch on the accumulator and started adding Freon. At first the pressure was literally 0. After dumping a full 16 oz in the pressure reads 20. I took out the jumper from the pressure cycling switch connector and put the connector back on. Now at 20psi the compressor clutch is cycling on / off due to low pressure as it should.

My question- Is it realistic to think the pressure should be higher than 20 psi after putting in 16oz of Freon?

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Cajun AUG 13, 02:05 PM
I am thinking you are on the low end of the scale. Charged my 86GT after an engine removal to repair exhaust leaks. My AC system was cycling between 40 & 55 psi.
sjmaye AUG 13, 02:17 PM
Hello,

I am sure I am low. Totally get that. What I don't have a feel for is if I dumped 16oz in to an empty system is it reasonable to expect 20psi? 40psi? If I should be seeing 40+psi I undoubtedly have a gaping hole somewhere.

Just what should I see after 16oz of Freon?
steve308 AUG 13, 03:42 PM
Add another half can and a can of leak dye. NEVER use a leak sealer! Go for a drive with the AC on and then let the car sit for a day or two. Check the AC condenser, all lines and of course the compressor using a UV light. (Amazon has them cheap). Your leak should light right up!
sjmaye AUG 13, 03:57 PM

quote
Originally posted by steve308:

Add another half can and a can of leak dye. NEVER use a leak sealer! Go for a drive with the AC on and then let the car sit for a day or two. Check the AC condenser, all lines and of course the compressor using a UV light. (Amazon has them cheap). Your leak should light right up!




I could be screwed. The can of Freon says it helps stop leaks. So, I assume this means it has a sealer in it. I had thought that would be a good thing. Should I still do as you say and add the 1/2 can and leak dye?
RWDPLZ AUG 13, 05:01 PM
If you started out with the system at 0, it wasn't actually empty, it was full of air. Best thing to do is evacuate it, draw a vacuum, check for obvious leaks, and then addR-134A and UV dye.
sjmaye AUG 13, 05:31 PM

quote
Originally posted by RWDPLZ:

If you started out with the system at 0, it wasn't actually empty, it was full of air. Best thing to do is evacuate it, draw a vacuum, check for obvious leaks, and then addR-134A and UV dye.



Can do. Can you tell me how many ounces of Freon I should expect to use on a empty system?
RWDPLZ AUG 13, 05:37 PM
For a full charge on an R-134A system, 3 of the 12oz cans.
sjmaye AUG 13, 05:58 PM

quote
Originally posted by RWDPLZ:

For a full charge on an R-134A system, 3 of the 12oz cans.



Got it. Thanks.
larafan AUG 13, 06:48 PM
I think you go back to where you began. When you converted, did you pull all connections and replace with updated o-rings for 134? Did you use proper flush and flush the entire system clean of old oil and any debris? Did you load new compressor with proper amount and type of oil and new 134 dryer with balance of correct oil ? Then pull a vacuum for recommended time and leak down check. Then charge with 134 to 80-85 % of R12 charge amount with 134 ? All that along with new compressor. It is a lot of work but is the proper way. The old orings will leak, the old oil lays in the bottom of components taking up space for freon and doing you no good as well as chance for moisture contamination. It all sounds picky, but AC systems are picky, it's not just the freon. Both my Fieros are fully converted as well as my 2 Sunbirds and all 3 have great working AC systems with 134. Also partial charging a system hurts components. It should be pulled down and preferably any freon recovered and the a full charge added before starting and performance testing. Hope this helps.

[This message has been edited by larafan (edited 08-13-2020).]