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Old 08-17-2007, 12:50 PM
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A/C problem

Last year I replaced everything on a neighbors 1989 Plymouth Acclaim related to the A/C except for the condenser core. The evaporator core, compressor, hoses, expansion valve and drier were all replaced with new components except for a rebuilt compressor from AutoZone. It seemed to cool just fine and had no problems until this summer when the compressor would occasionally lock up and leave the drive belt squealing. When this happens the A/C switch can be turned off for a couple of seconds and then turned back on and it will run fine for a day or so before doing it again. I set up my gauges and the high side pressure was 375 PSI so I removed the condenser core and sure enough it was restricted so we replaced it and that brought the high side pressure down to 225 PSI which according to my Hyanes book is normal for this car. The compressor does not make any unusual noise, runs smoothly and the system cools better than before the condenser change but the stalling problem did not go away. Could this be a bad compressor? It does not seem to have any tight or rough spots when turning by hand and except for the occasional lock up seems normal. I would expect a bad compressor to make a rattling noise or be rough when turned by hand but this thing does not seem to have any of those problems and the cooling fan runs normally when the A/C is on. What else would I check for that might cause this? It is really hot right now and I would like to help this old fellow and his wife out on this since he has spent so much money on it already but I am at a loss at to what to check for now.

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Old 08-17-2007, 01:23 PM
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Hi Red,
After changing the condenser, when the compressor stops,
does it come back on only using the A/c switch, or will it start back up on
it's own after sometime, like a circuit breaker.
rich

PS Chrysler put two relays on some of there cars w/two cooling fans,
with low & hi speed & the low side fails a lot

Last edited by richard stewart 3rd; 08-17-2007 at 01:43 PM.
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Old 08-17-2007, 01:53 PM
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A/C problem

I have been working in auto A/C for several years and the only time the compressor would lock up to the point of squealing the belt was when the compressor was beginning to fail. The fact that the condenser was plugged can mean two things, 1) it got plugged from the previous system and the debris in the system as also got into the new compressor and damaged it, or 2) the new compressor is coming apart in side and that is what plugged the old condenser and/or plugging the new condenser, either way you may need to replace the compressor and then make sure you flush the lines and replace the receiver/dryer or accumulator filter which ever this car has. Also, when you replaced the compressor did you charge with new oil or did the compressor already have oil in it? I would guess the system would expect about 8 to 12 oz of oil. And what oil and refrigerant are you using?
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Old 08-17-2007, 01:55 PM
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A/C problem

Does the system cycle on and off when it runs?
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Old 08-17-2007, 03:01 PM
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The system runs normally until the compressor locks then it will stay locked up until the clutch is switched off. Once the clutch is disengaged it will start back and run just fine (for a while) after it has been off only a few seconds. This thing was charged with 134 and Ester oil (8 oz) and the compressor was shipped empty so there is no mixing of oil. The Ester was called for on the tag that came with the compressor the compressor was ordered for 134 refrigerant if that makes any difference.
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Old 08-17-2007, 03:36 PM
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Throw some more oil to it, If that doenst help then there might be somthing in the compressor.

would try a oil charge first tho - It cant hurt anything

I had to put one in my parents Cavalier the other day becasue the compressor made so much noise it would drive you out of it.
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Old 08-19-2007, 07:04 AM
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A/C problem

You could try to put more oil in it, but I am not sure that would help. The ester oil is fine and will mix well with 134a as well as other refrigerants. The compressor might not be locking up in that if you have too much 134a in the system and the amount of force to compress the refrigerant is so great that belt can not grip well thus is slips, I am not quite sure but this may be your situation. So, you can let some 134a out to thus lower the pressure or better yet switch to another refrigerant like ES-12a (envirosafe 12a). ES-12a will run a much lower head pressure and does compress much easier. This refrigerant is much better that 134a and much better on the overall A/C system. I will leave the 134a in a system until it needs refrigerant and then I will always switch to ES-12a. You can get ES-12a on ebay and at a lot of online refrigerant companies. You will probably only need 2 to 4 cans, so start out with only 2 cans and see how it does. You charge ES-12a with the can in the liquid position.
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Old 08-19-2007, 07:52 AM
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Thanks for the info I will check out the ES-12A since I am no fan of 134 but so far I have only heard horror stories about most R12 replacements but the ES-12A is new to me and I will definitely take a look at it. I had not thought of reducing the 134 charge and since I will lose it anyway I will certainly give that a try and let you know what happens.
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Old 08-24-2007, 11:22 AM
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Just to update in case someone is interested, I think I have the problem fixed now and it was very simple. OldChevy suggested it might be too much 134 charge (it was) so I drained the system, pulled a vacuum, added 2 oz of oil and recharged with only 24 oz of 134. The system calls for 40 oz of R12 and I had 34 oz of 134 in it because I know there is supposed to be less than the R12 but apparently even less than I thought. It now cools just fine, really good in fact, on only 24 oz of the 134 and the pressures are down even lower and best of all NO lock-up!

Thanks guys I was about to drop a couple of hundred bucks on a new compressor that was not needed.
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Old 08-24-2007, 11:33 AM
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Kewl, oldred!
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Old 08-24-2007, 12:04 PM
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A/C problem fixed

Glad to hear you problem is resolved. 134a is a usable refrigerant and will work when set up correctly. Adding the extra oil is ok as the system is probably at the correct level. 10oz of oil is good. If you ever get too much oil in the system it will cool for a few minutes and then get warm.
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Old 08-24-2007, 04:23 PM
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I had added the proper amount of oil when I first installed all those new parts so I knew exactly how much oil was in it and when I drained it this time I guess-timated that 2 oz was about how much oil was lost, at least that's about what it looked like.
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