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Discussion Starter #1
I've been having trouble with the air conditioning in my 87 CSX and am wondering what the cause could be. The system is original with the exception of R-134a oil and refrigerant. After I run the system for about 10-15 minutes, the compressor will seize and the clutch will begin slipping. I noticed the air isn't terribly cold, and the heat isn't very warm. My guess is that the evaporator isn't evaporating the liquid, causing the compressor to compress a liquid. After I turn off the air conditioning for a while, the compressor will turn again and the system will run without troubles. I have run 134a in 2 other R12 systems without this problem, so I'm hoping that I just have a clogged heater box. Let me know what you guys think.
 

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Your compressor has gone bad and you have metal filings/shavings clogging up the system at the h valve which meters how much refrigerant flows into the evaporator.

When you get a logjam at the h valve that means no refrigerant is getting into the evaporator which leads to no cold air.

The compressor is still trying to pump refrigerant during this time and will eventually sieze completely.

Your system needs a complete overhaul.

Steve
 

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What is the best method of cleaning out the system? I recently replaced the compressor and lines from a low, low mileage car, allowing me to fix all the leaks. I never had the expansion valve apart, so there is a good possibility that it is clogged. I'll take the system apart and inspect everything, and I'll probably replace the heater core and look at the air box while I'm at it. Thanks for the info, it makes sense since the old compressor was in pretty bad shape.
 

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Couple of thought here. I am guessing but the way you wrote your post the clutch stops turns but the pully still turns. Check the gap with a feeler blade. I don't know the spec for that one most are around .020". If its too wide it can slip. Also when it was converted was the dryer changed and how much of the old oil came out and how much new oil was put in. Also what kind of oil was used? If the compressor is throwing trash it should be getting caught at the dryer. Also how much R134 was put in? When you switch from R12 to R134 the amount of R134 put in should be about 70 to 75% of the amount of R12 it would have held. The high side should run higher numbers then when R12 was in it. This also puts a strain on the clutch holding. Most cars that came factory with R134 have bigger condenser to lower the high side numbers.
Tim
 

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I was just following up on posts I made and found I missed you posting near the same time I posted. Your new post says you want to replace the heater core. Check the evaporator for dirt on it while in there. Manufactures just started putting replacable filters in some cars systems. So ones without it get build up on them. In the last year I have removed about 6 evaporators that were so clogged they performed poorly. It seems it does not take much to cut performance. Also I don't know what year mopar started using crappy leaky cores but they did. So think about replacing it. The best way to check one is with the system full sit it out in the hot sun for a few hours (windows closed) and take a sniffer inside the car and sniff with the system with it off. You can turn on the fan to sniff a vent and move the air to it. They seem to only leak when hot as soon as the evaporator cools like when using it it will stop leaking. This will drive you crazy. My 94 van had one it could lose its charge in 2 days or 6 months. It just depended on how hot the evaporator was.
As far as cleaning a system. I have known guys that will use a garden hose on lines, evaporators, and condensers. They were all out of the cars and they used compressed air to clear them of water. I would only consider this if I had a really bad contamination problem and had at least a week to let them air dry before putting the system back together. At work if something gets bad we replace everything. The county I work for rarely will clean a crapped up system. Thinking here in Florida is differant then the thinking where I worked up north. I use my A/C every month of the year here. The last one we cleaned was a old ford truck being used for undercover work. They wanted it fixed cheap. They use a oriface tube system. The system was run with little if any oil and was throwing some metal but still building good numbers. We oiled it up filled it up and would runs it for an hour. Recover the freon and clean the oriface. We did this about 3 times and the trash stopped building up. We then put in the new oriface tube. It has worked fine ever since.
Tim
 

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Tim, thanks for the reply. I've known the condensors plug up, as I'm a member on Ramchargercentral.com and that is the #1 reason the AC and heater systems don't perform well. In fact, it's such a problem that they have a *how to* on cleaning the evaporator and heater core. I was thinking about using a garden hose, and I don't think having water in the system would be a problem if I had a vacuum pump on the system for 6 hours or so. With a vacuum on the system, all the water should boil out in a matter of hours.
 

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6 hrs sounds good in theory but the point water boils in a vacuum varies with temp and how much vacuum. There is a chart to show how much vacuum you need to pull at what temp. When I was up north vacuuming a system in winter was a joke. You can't pull a hard enough vacuum (with the average pump) to do it on a 20 degree day. Do it on a hot day in the sun. If temp is 70 or lower run the enige and turn on the heat to low speed high temp. Also use your old dryer for the 6 hours. There is a disicant bag in there that will fill up with moisture and not release it. Change it to your new one and pull it down for another hour. I found this page check it out. When I bought my pump it listed what vacuum it was capable of pulling. The 3 I looked at all could pull to a differant level. I do not know if they still do that and if your using an older pump does it still perform well enough fo pull a hard vacuum? http://www.robinair.com/new/acsolutions/acvacuum/acvacuum.php#eff1
Tim
 
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