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A/C kicks off immediately. Low-side over 150.

dmakieve17 on Mon August 15, 2011 8:58 PM User is offline

Year: 2002
Make: Toyota
Model: Celica
Ambient Temp: 90
Pressure Low: 150+

So i have been having a hell of a time figuring out what to do with my a/c. I just joined this forum hoping to finally get some answers.

I own a 2002 Toyota Celica GT-S. I bought the car in 2007, and A/C worked great for years. Summer in Tucson, AZ hit and problems came. At first, A/C did not seem to be working to full potential. Air was not ICE cold like it had been in past, but was definitely still cooling well enough. Then one day cold air stopped suddenly, and was replaced by warm air. Also A/C button began flashing. I assumed this was simply my cars way of telling me it had run low on refrigerant. I now know this was QUITE an assumption.

I bought refrigerant today, hooked up the cheap pressure gauge to the low-side valve and BAM, pressure shot up as high as the gauge can read. Over 150. However, the compressor is technically not kicking on. When i press the a/c button, compressor kicks on, pulleys running and fans spinning, and then stops within a second or 2. Not even long enough to walk from the cabin of my car to the gauge. I have read on faulty relays for the clutch, but i have already tried swapping one of the fan relays with the one for the clutch, no change.

At this point im at a loss. I would prefer not to take it to the professionals, and i am hoping to hear i havent wasted my money on refrigerant.

Simple recap: A/C never produces cold air. Compressor shuts itself off almost immediately. And Low-side pressure is VERY high.

Any info would help. Thank you

DaveMcKenz on Mon August 15, 2011 9:24 PM User is offline

Several potential explanations. Could be a bad charging hose connector. If so, it may not be opening the service valve and you are simply measuring can pressure, rather than system pressure. Also flashing light may mean impending compressor seizure. There is a speed sensor that compares compressor rpm with engine rpm. Beyond a certain difference, it shuts off the clutch. You could have both of these problems.
Good luck,

Edited: Mon August 15, 2011 at 9:27 PM by DaveMcKenz

GM Tech on Mon August 15, 2011 9:48 PM User is offline

Your rpm sensor mounted on compressor knows the compressor is not turning the same speed as the pulley-so it shuts off compressor and flashed the a/c button light to let you know there is a serious issue--as in your clutch is slipping--it turns off compressor so it does not smoke the clutch and pulley and belt and cause you to "walk home" this is a safety feature presented to you by Toyota. Now what to do to fix your problem...I usually just go get a salvage yard pump and solve it that may choose to install a new compressor...

There is a small possibility that only the rpm sensor is faulty- happens sometimes but is very rare....I'd go with the salvage yard pump for $75 if I were you......

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

mk378 on Mon August 15, 2011 10:22 PM User is offline

Get rid of the cheap gauge. Don't add any refrigerant now, and certainly never add anything with stop leak, etc. in it. Low side pressure is normally high when the compressor is not running.

Check that the compressor rpm sensor is plugged in and wires not damaged. Check that the belt is tight, if it is adjustable.

JJM on Mon August 15, 2011 11:42 PM User is offline

Assuming that gauge is right, 150 PSI on the low side at 90F means something is seriously wrong. Static pressure should be no more than 105 PSI. The A/C light flashing typically indicates the compressor is starting to seize up. Good thing the compressor is shutting off... next step with those pressures would be flying shrapnel.

You cannot properly service an A/C system without a complete gauge set, any more than a doctor can diagnose blood pressure without diastolic and systolic numbers.


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