A/C Compressor Operating Temps

[vettenuts]

Just had the heater core replaced. The A/C compressor isn't running when I put it on A/C. Its 41 degrees and rainy (cold & damp). Does anyone know if there are temperature/humidity parameters where the PCM won't allow the A/C compressor to run? I wanted to test it to make sure they adequately re-charged the system and don't want to wait until warm weather since they may not assume fault at that point.

 

[streetglideok]

Can't say for certain on the KJ, but as a general rule of thumb, around 25-30psi on the low side will turn off the compressor. Mine normally turns on at 41* though. I would be back and ask them to reverify things. Are you sure they charged it back up?

 

[vettenuts]

It needs to be evacuated for the heater core job and there was no refrigerant shown on the slip. He told me if it was charged when it came in then they use the same for re-fill. I think there is a timing function in the PCM, I will run it longer and see if it comes on.

 

[streetglideok]

I would tell them it doesn't work now, if it worked before then it should now. Otherwise, check the basics. Check the resistance of the clutch coil at the connector, check for power to the clutch, etc.

 

[vettenuts]

Took it back to the dealer. Technician removed 0.8 lbs of refrigerant and put in the same amount. Turns out system was low. He re-filled but noted there may be a leak. We'll have to monitor once the warm weather returns but for now it is working.

 

[streetglideok]

Took it back to the dealer. Technician removed 0.8 lbs of refrigerant and put in the same amount. Turns out system was low. He re-filled but noted there may be a leak. We'll have to monitor once the warm weather returns but for now it is working.

Some guys in these shops bother me. If you notice it is low on charge, then you tell the service writer, and you see about addressing it then. They shouldn't just put the undercharge back in. The R134A charge is what circulates the lubricant(PAG oil) in the system. Undercharged and overcharged systems won't do that, and starve the compressor of oil. I would get the charge correct, or disable the compressor until you do so.

 

[vettenuts]

That's now taken care of, the new issue is the heat is very hot. Blend door is definitely moving but the air is not as hot as it was prior to the heater core replacement.

 

[streetglideok]

Check the coolant level, make sure its at the full mark. Does the engine temp gauge reach the middle mark and stay there moving or staying still?

 

[vettenuts]

Got it. It turns out there is a manual calibration procedure for the blend door that applies to my daughter's model year. Once I did the calibration, the heat was once again hot.