View Full Version : Air condition not working after mechanic put in new thermostat

08-31-09, 04:45 PM
Ok, my air has been working fine every since i had o ring replaced on the compressor because it was leaking, and that was over a month ago. It has been very cold, but i had to have my thermostat replaced because the car kept over heating in while on in park. Now, my car is back to blowing out hot air again. I got no condensation under the car anymore either. I watched them put 1 gallon of antifreeze in the reserve to , and 2 gallons of water. The reserve tank, is now way below full. Why why why! I spent 1 month not driving my car because its to hot down here and i had no air, now that i get it fixed, its broke again. Is there anything i can do to try and fix this because the mechanic wont answer now. He came to my house

08-31-09, 05:05 PM
ok, i just looked at the empty gallon of antifreeze that the guy put into my reserve tank, and it says do not add water. I seen them add 2 gallons of water, to the gallon of antifreeze they put in the reserve tank. Could this have caused a problem for me?

08-31-09, 06:20 PM
:hmm:sounds like you need a new mechanic

08-31-09, 08:30 PM
X2 on the new mechanic... Adding water when its not needed won't cause the AC to be non op tho. It might become an issue if its really cold in the winter months, since the ratio of coolant-water mix is lower, it could freeze over causing a cracked engine block. Is the level when the engine cold where it should be now? If not purchase same kind of antifreeze (should be dexcool) and add to level when engine cold. My guess is a coolant temp sensor for the AC wasn't plugged back in, and compressor won't engage. Temperature gauge in the dash working? Any trouble codes? Keep us posted.

09-02-09, 08:26 AM
the speedometer is busted, like tons of others. If anyone has a new one for me let me know. So, on what you were speaking on that wasnt pluggeg back in, where is it and how can i check to see if it was plugged back in.

09-02-09, 08:57 AM
CutNpaste info from the service manual:

HVAC Compressor Clutch Does Not Engage
Diagnostic Aids
A/C compressor clutch will not engage under the following conditions:

The A/C high side line pressure is over 2957 kPa (429 psi).
The A/C low side line pressure is under 138-172 kPa (20-25 psi).
Throttle angle is at 100 percent.
Engine speed is more than 5500 RPM.
Engine coolant temperature (ECT) is more than 121C (250F).
Ambient air temperature is less than 5C (40F).
Engine is idling at a low unstable RPM.
Compressor clutch engagement cannot be used to determine status of the low pressure switch. The low pressure switch is one of several inputs to the HVAC control module for A/C request authorization. A/C request is one of several inputs to the powertrain control module (PCM) that control A/C compressor clutch engagement.

To accurately determine what pressure the A/C low pressure switch opens and closes at use Kent Moore GE-47742 which will allow the technician to measure the switch point pressure at the switch.

Using a scan tool, monitor the "low pressure switch" status while monitoring the "low side" pressure at the switch to determine the switch points of the low pressure switch.

The low pressure switch "connector seal" must be removed before plugging it into the switch for testing. The "plunger effect" of plugging the connector with seal into the switch induces a pressure on the back side of the switch, this pressure will skew the opening/closing characteristics of the switch 5-10 psi until the pressure bleeds off. The time required for the connection induced pressure to bleed off can take 20 minutes or longer.

Test Description
The numbers below refer to the step numbers on the diagnostic table.

The A/C compressor output is disabled if the engine is idling at a low unstable RPM.

The A/C compressor relay output is disabled if engine coolant temperature is above 121C (250F). The engine coolant indicator will illuminate at this temperature.

This step ensures that the HVAC control module is receiving an input from the A/C switch.

These actions will enable the A/C compressor to operate.

This test ensures that there is sufficient refrigerant in the A/C system. The specific values come from the A/C System Performance Test in Heating, Ventilation and Air Conditioning.

The A/C Low Pressure Switch parameter is out of range when the HVAC control module interprets the signal being below 138-172 kPa (20-25 psi).

This action will simulate a closed switch condition. If the Pressure Cycle Switch parameter reads Low Pressure than there is a circuit condition or a condition with the HVAC control module.

The A/C compressor relay output from the powertrain control module (PCM) is disabled if the A/C high side system pressure is interpreted to be higher than 2958 kPa (429 psi).

If there was sumthin up with the coolant sensor, you would get an error message "engine overheat" on dash.

09-02-09, 10:10 PM
the broken speedometer was actually covered under a class action suit that GM lost. You may still have time to get it fixed by GM if the statute stills exists.