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A/C Compressor won't stay running


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14 replies to this topic

#1 brykel

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Posted 09 June 2004 - 05:43 PM

After charging w/ about a half a can of R134a, the a/c compressor stops running in my 93 Loyale...i've replaced all o-rings, rec/dryer, blew out all lines and evaporator, and replaced oil in the compressor with PAG...i had a vaccuum pulled and it holds at 30"...why can't i charge this thing?

#2 nutt7

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Posted 09 June 2004 - 11:03 PM

Do you have a gauge? It should read between 25-45 when its up to spec...compressors often turn off if there is not enough pressure, or the compressor simply isnt turning fast enough...

there are a couple things to check:
-if your compressor was off, then as you charged half a can of r134 it turned on, then turned off after a minute, its probably because the initial pressure of the r134 entering was high enough to allow the compressor to run, but as it cycled through the compressor and all the lines the pressure got too low. Your system should take at least 2 12 oz cans of r134, maybe more...use the r134 with pag and sealer and all that already in it...it is crucial to get a gauge! dont want to over or undercharge!
-If that doesnt work, run a wire from your battery to the compressor and see if it stays on. if it doesnt, the clutch may be bad, if it does stay on, check the AC system switches, pressure, wiring etc

hope this helps,
eric

#3 brykel

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Posted 10 June 2004 - 12:25 AM

Thanks for good info Eric...i have a guage...the compressor kicked on a few seconds after i started charging, maybe around 5 psi...so i let it run for maybe five minutes to stabilize...as i added more 134 and the pressure got up to about 20 psi the compressor shut off and insatantly the pressure went up to like 60 or 70 psi...this with only about half a can!


I didn't use the 134 with the sealer/oil because i poured some PAG directly into the compressor and rec/dryer and also replaced all the o-rings in the system and there are no leaks...the system holds a vacuum nicely...

I'll try running a wire from the batt and see if it will charge...

#4 rallyruss

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Posted 10 June 2004 - 02:24 AM

use the r134 with pag and sealer and all that already in it..



NOOOOO:eek:

pag oil good
sealer really bad
the sealers are ruining every thing from compressors to a/c machines. dealers will void any warranty on A/C components if the system has been contaminated with sealer. same goes for a/c machines. I recently attended a class on this and the only solution for a system with that sealer junk in it was to replace ALL the components it came in contact with.

#5 Nug

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Posted 10 June 2004 - 06:42 AM

Oil directly into the compressor? NOOOO! Well, I hope you put it in the high pressure side. If you poured it into the low pressure side, well, liquids don't compress real well.


Watching compressors lock up and explode is fun.

#6 4FOR4

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Posted 10 June 2004 - 09:24 AM

If putting oil in it filled the cylinders (making it a pump), you'd know if there was damage because the compressor would be running terrible, not compressing, etc. My A/C instructor said it best "a compressor becomes a pump, just before it becomes a wreck".

If you have a set of refrigeration gauges, connect to the high side as well. It sounds to me like the compressor is going off on high head pressure. There is a safety switch that will trip at about 350 psig. Normal operating is in the 200s but will change with load.

If you find that with only half a can its going off on high head, your metering device is probably plugged. I had this happen when a compressor went bad and metal pieces were migrating around the system and got stuck in the very small hole they use for refrig control.

To clean it out, I blew the line backward, from the low side connection, through the evaporator and metering device out the other side of the silver can gismo with the line disconnected after the can. With that disconnected you might want to do the other half of the system too to insure debris removal from that side. Now of course you'd blow this clean with some inert gas like nitrogen because letting refrigerant out is illegal and environmentally unfriendly.
If you do find alot of metal, which will be very shiny specs in the oil that is pushed out, you have a compressor thats failing and should be changed out.

Good Luck.

#7 brykel

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Posted 10 June 2004 - 09:54 AM

Thanks for all the great info everybody...just to let you know, i dumped the old oil out of the compressor and put in the same amount of fresh PAG oil, just like the Haynes manual says to do...i'm pretty sure it was the high side input but it was definitely the same hole the old oil came out of...


Sounds like it may be possible that the high head safety switch is bad...does anyone know how to replace or test this?

#8 4FOR4

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Posted 10 June 2004 - 11:09 AM

Have you checked the high side pressure? What is it when the compressor quits?

The sensor is a 2 wire device located in the line going to the metering device. I think they are normally closed, opening on high pressure. Try a jumper wire between the 2 leads.

#9 brykel

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Posted 10 June 2004 - 11:47 AM

I seem to be having trouble locating the metering device and the associated wiring. In this car (93 Loyale), there is a pulsar system located on the compressor which shuts it down if the clutch isn't rotating as fast as the compressor. Could these be the wires i need to jump? The only other components mentioned in the schematic are the relay, which i did check, the fuse (OK), a/c switch, thermo switch, a/c amplifier, pulse coil, blower swithes and fan relays. Does this car even have a metering device?


I don't have a high side guage, unfortunately.

#10 4FOR4

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Posted 10 June 2004 - 12:01 PM

Every refrigeration system needs some sort of metering device to provide a point at which the hot liquid can drop pressure and become a gas and absorb heat in the process. This is going to be nothing more than an orifice plate or similar.

On the Subarus I've dealt with, the metering device is located in or near the cylindrical component near the strut tower, passenger side, under hood. The line coming from the condenser (which is up by the radiator) should be a solid, possibly aluminum tube, and will run to the cylinder in question. Out the other side of the cylinder (which may be a refrigerant reservoir) is a smaller tube that leads through the firewall to the evaporator in the passenger compartment.

I think there should be a high pressure switch right near that, possibly just before the cylinder as the line approaches from the condenser. Its not very big and will have wires connected to it.

#11 brykel

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Posted 10 June 2004 - 12:26 PM

I think the Loyale is different...the older Subies had an electrical connector right on the rec/dryer which is down by the pass side headlight...this one doesn't...the only components up by the pass side strut tower are the a/c relay, main fan control relay and a/c fuse...any ideas where the safety switch might be in a Loyale?

Btw, i connected the compressor directly to the batt with the a/c on and everything works great and i am able to finally put more 134 in.

#12 brykel

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Posted 10 June 2004 - 12:51 PM

OK, i found an electrical connector with four wires that is connected to the line that goes between the condensor and rec/dryer. Could this be the switch i need to replace? Judging from the color of the wires going into it, it appears that it is called a trinary switch, according to the Haynes schematic. One wire goes to the a/c switch, another to the rad fan relay, another to the rad fan motor, and the last one to the a/c amplifier. If this is the correct switch to test/replace, how do i remove it? Do i have to discharge the system? It is screwed into the line.

#13 4FOR4

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Posted 10 June 2004 - 12:58 PM

I think you'll want to test in place. Try to start compressor, if the compressor stops, check the switch you found and check if its open. Was it closed before pressure built? Do you have a meter?


To make your life alot easier, find someone who has a refrigeration manifold set so you can see the operating pressures of the system. Otherwise your flying blind.

#14 brykel

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Posted 10 June 2004 - 01:38 PM

Ah ha! I'm fairly certain now that my compressor is binding, causing the sensor to shut it down...when i jump that trinary switch, the compressor comes on, runs for 20 sec or so and shuts down...when i hook the compressor directly to the batt, i can see that the belt is having a hard time keeping it up to speed, even though the belt is good and tight. I have about a can and a half of 134 in the system now. Guess i'm off to the junkyard to buy a used compressor. Is there any way to test a compressor on or off the car?

#15 Nug

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Posted 10 June 2004 - 11:56 PM

You can half rump roast test it. Give the compressor a turn, and see if it tries to suck your finger in the low pressure side, and push your finger off the high pressure side. Test several, and find the best one. Try and find one off of a car that has all of the refrigerant lines still attached, so there will be less contamination in the compressor. Also, avoid any that have big clumps of dirty crap around the seams. It may have been leaking.


Brake cleaner can be used to clean it out. A small amout of refrigerant oil poured in and worked around will keep the pump lubed long enough for the rest of the oil in the system to reach it.

Remember, vac it out for at least half an hour, preferably longer.




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