: A/c blows warm. 3 yr old a/c compressor. Fully charged w/ r134a



catera00
03-18-11, 03:16 PM
I had my a/c compressor replaced at the dealer 3 years ago. It worked great till last summer. The a/c works in 65 degree or below weather. Sometimes it will get a bit cooler on the highway but not cold enough. There is neon green dye in the system (The dealer added this to verify there were no leaks) which as not surfaced any where. So I dont think theres a leak. The high side pressure is at about 45 psi.

I'm wondering if there a blend door or valve somewhere that might be stuck open that could be causing the air not to cool? It doesnt blow hot air or anything (except when the heater is on), just however hot it is outside. Is there such a thing in the Catera? What would cause the a car with a newer compressor full of refrigerant not to blow cold air? The Compressor clutch kicks on as does the two fans in front. :flame:

jimsbox
03-18-11, 03:22 PM
45 is way low for high side with compressor running. With R134a in Tucson I would expect around 250 psi, but I am a shade tree mechanich, not an AC tech. I do all my own AC vwork and it doesn't sound like the compressor is compressing the refrigerant with that low a value with the compressor on. Hopefully an AC tech will jump in. What is your low side reading?

catera00
03-18-11, 05:49 PM
well maybe Im wrong. It could be the low side. Its the port on the drivers side next to the dip stick. Not the one lower in front by the fan

investor74
03-18-11, 08:30 PM
You're right, the port near the oil filler/ brake fluid tank is the low pressure port. One thing, give it a little gas when you measure the low side pressure. I noticed that it seems that there is plenty of pressure at idle, but when you give it a little gas, the pressure drops and you really need more r134. I noticed that because the compressor would run at a stoplight at idle, and then cut out when I stepped on the gas. The lowered intake pressure caused the compressor to cut off to protect itself.

catera00
03-19-11, 12:49 PM
ok I took some more readings.
High side is 65psi
Low side is 50 psi
High side seem way too low to me. Outside temp is 70 degrees and dry. (Arizona)

jimsbox
03-19-11, 08:38 PM
Sounds like you are probably low on R134a. Even at 70 deg the high side should be well over 100 psi, I don't have a chart in front of me but I would guess around 165 to 200psi. You can look it up with google to get an idea. The trick is the pressure readings are dependent on the refrigerant used and the ambient temperature. The higher the ambient temperature, the higher the high side reading (and low side as well). Don't over charge or you may damage the compressor with high head pressures and an over charged system cools WORSE than a properly or slightly under charged system.

catera00
03-20-11, 02:20 PM
Sounds like you are probably low on R134a. Even at 70 deg the high side should be well over 100 psi, I don't have a chart in front of me but I would guess around 165 to 200psi. You can look it up with google to get an idea. The trick is the pressure readings are dependent on the refrigerant used and the ambient temperature. The higher the ambient temperature, the higher the high side reading (and low side as well). Don't over charge or you may damage the compressor with high head pressures and an over charged system cools WORSE than a properly or slightly under charged system.

You were right. Took it to a mechanic and it was low. He said its normal to loose 2 oz a year. Crazy. THanks everyone! Now its blowin super cold again!!