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Pressure high on both sides

howell33 on Mon September 10, 2007 3:41 PM User is offline

Year: 1994
Make: chevrolet
Model: s-10
Pressure Low: 120
Pressure High: 120

You folks were a huge help when I replaced my a/c compressor. It ran well for about 5 weeks then today stopped cooling. I put the gauges on it with engine off and both sides are reading 120lbs of pressure. When running correctly the static pressure (engine off) was about 70lbs on both sides. Obviously no leak in system so my guess, being an amateur is that the new orifice valve (flow valve/filter?) I replaced clogged up completely causing the low side to pressurize to 120lbs or more since that's where my low side gauge maxes out. Am I correct and if so what's my next step?

Thanks, Alan

TRB on Mon September 10, 2007 5:19 PM User is offlineView users profile

Is this a 2.2 L vehicle?

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Chick on Mon September 10, 2007 5:24 PM User is offlineView users profile

What is the outside temp when you had 70psi static?? If over 70 degrees you may have a leak, but you do have enough pressure to make the comnpressor run..So, take the plug off the cycling switch on the accumulator "IF" you have a 6cyl engine..Jump the wires and see if it starts. If it does and blows cold, then change the cycling switch..If you have the 4cyl engine with the V5 compressor is the outer hub turning with the AC on?? If it is, you probably have a no pumper, which we can get into once we have all the info..Also, with either the R4 compressor or V5, with the ac on, tap the outer hub of the compressor uinwards to sdee if it engages..
Befor you do any of this it would pay to check fuses, relay etc...See if 12 is getting to the clutch coil..(Bad cycling switch it won't)

So give us the engine size, which refrigerant you're using, outside temp with the 70psi static pressure..The 120 just means that it's hot under your hood...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

mk378 on Mon September 10, 2007 5:44 PM User is offline

The static pressure will vary with the temperature of the car.

Was the compressor running when you read 120 psi low side? If you have a V5 and that was the case, the control valve is probably bad. With a bad valve, the compressor will turn but it will not compress.

howell33 on Mon September 10, 2007 11:52 PM User is offline

Outstanding! When I shorted the plug off the cycling switch on the accumulator the compressor ran and air was cold. I replaced the switch and added a little 134a since I had bled a small amount off. Now after idling for 20 minutes I'm getting 27lbs pressure on low side and 195lbs pressure on high side with 35 degrees coming out of the center vent. Static pressure on both sides (engine off) is 50lbs at 80 degrees outside temperature. What do you think? Leave it as is or add 134a to bring high side closer to 225lbs?

Chick on Tue September 11, 2007 5:09 AM User is offlineView users profile

50 psi at 80 degrees would mean the system is empty (just gas left)...are you sure your guages are working properly, as well as your vent thermometer??

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

howell33 on Tue September 11, 2007 11:45 AM User is offline

Perhaps I'm misunderstanding what ambient temperature is, I assumed it was the temperature outside the car. Are you looking at ambient temperature as the temp at the vent with the car off? If so should the static pressure be close to the temp in the car and will the static pressure increase as the car temp increases? Also, should I add more 134a to bring the high pressure to 225 or 250 or leave it where it is?

Chick on Tue September 11, 2007 12:13 PM User is offlineView users profile

ambient temp is the temp of the air passing over the condenser, so yes, outside air, and the static pressure should be close to that, I would suggest evacuating and recharging by weight. You have to have the correct charge in the system..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

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