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AC Compressor Keeps Going Out

Steven Monteith

Steven Monteith

New member
I have 2000 GP top swap with an XP cam, 3.2". Today is the 3rd time my AC compressor has gone out in the past several weeks. As well as the Compressors crapping out, the aluminum line that goes into the compressor has cracked twice in 2 different spots. 2 of the times that it has gone out is when I was open throttle for just a few seconds, and as soon as i get off of it, it goes hot. My shifts points were raised to 6,200-6,300. Obviously there is too much pressure causing the 2 cracks and this last time there was a whole in the compressor. I'm wondering if it has to do with the RPMs being so high or maybe some kind of electrical problem. Any ideas would be highly appreciated.



Thanks,

Steven
 


Did the AC work well before it went out? And who's charging the system? Is the appropriate amount of oil being added?
 
02NavyBlue said:
Did the AC work well before it went out? And who's charging the system? Is the appropriate amount of oil being added?
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Yes it was working good. I never had to do anything with the ac for the past 4 years that I've been driving it. 5 years ago my dad had the dealer put in a new compressor. A mechanic I know that has done a lot of work for me and my family. He does a lot of AC work so I trust him that he is doing it right. The first time it went out it was from when I was gunning it (that was with the dealer installed compressor).
 


There is a pressure switch on the low pressure side of the system and the high pressure side.The high pressure switch cuts the power to the compressor clutch during too high of refrigerant pressure(overcharge,bent up or dirty condensor,Ect).The low pressure switch cuts the power for too low of pressure(low heat load, leak,Ect.)The high pressure switch is on the drivers side under the high side gauge fitting i think,I may be wrong tho.


By my thinking, even if the high pressure switch was bad,i dont see it cracking aluminium lines if the system was charged properly and doesnt have too much oil in it.Because when you get on it, it should shut off before 5k like was said earlyer.Now if it didnt, then it could definitly screw a compressor up.lol.But even then,the high pressure switch would shut it off.
 
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goldgp said:
There is a pressure switch on the low pressure side of the system and the high pressure side.The high pressure switch cuts the power to the compressor clutch during too high of refrigerant pressure(overcharge,bent up or dirty condensor,Ect).The low pressure switch cuts the power for too low of pressure(low heat load, leak,Ect.)The high pressure switch is on the drivers side under the high side gauge fitting i think,I may be wrong tho.


By my thinking, even if the high pressure switch was bad,i dont see it cracking aluminium lines if the system was charged properly and doesnt have too much oil in it.Because when you get on it, it should shut off before 5k like was said earlyer.Now if it didnt, then it could definitly screw a compressor up.lol.But even then,the high pressure switch would shut it off.
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To add a few things: even though the system cools well doesn't mean there's not some problem with the charge, or a restriction on the suction or discharge side that could lead to a pressure related failure. While the proper way to charge a 134a system is to properly evacuate the system with a vacuum pump capable of pulling 500 microns--(BTW ford says 10,000 is OK)--And then to Weigh in the charge according to the underhood sticker or shop manual, Any time you recharge a system "post-maintenance", you really should hook up a proper manifold (set of gauges), and refer to a "Ballpark chart". For example, if the outside temp is 85 deg. F, your low side pressure should cycle between about a high of 60 PSI and a low of maybe 30 PSI. If it pulls down to 20 or 25, that's where the low pressure cutout should de-clutch the compressor. By the same token, the high side should climb to perhaps 200-225 PSI.--On real hot days (100-110 F) the high side could go as high as 325-350 PSI, and this is where the high side safety switch should cut the compressor off. It's also my understanding that the PCM can be programmed to cut the compressor past a certain % of throttle opening, i.e. 40-50%, (A point clearly above normal highway cruise) as well as a Max RPM.

When doing a driveway test you also need to move air across the condenser coil as if going down the road, I took a large blower fan out of a residential air handler, and it simulates 60 MPH just fine. This way you can rev it and watch the gauges in the driveway while replicating what's really happening on the road. Hope this helps you narrow it down. While doing this run the unit on Max AC, max fan, first with the windows down, and if all's well, then close the windows and monitor temp. drop. as the air gets re-cooled and drier inside the cabin, you should see about a 20 degree difference between supply and return, and a terminal temp of as low as 50F or even less depending on the O/S air temp. Beware a system that cools "Too Well", this is often a sign of a moderate to severe overcharge, and this leads to stacking in the condenser and possibly slugging the compressor (You want cool vapor and perhaps even droplets coming back to the compressor--this is what cools it--but if your Evap becomes flooded, it can't boil off the refrigerant quick enough and then you start sending liquid back to the COMP., and liquid doesn't "Compress"--hence the term "Slugging" (BANG!). Hope this helps, mike
 
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