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my AC stopped blowing cold

09-10-2007, 11:13 AM
my AC stopped blowing cold/

Turns off at about 50 low and 150 high

Turns on at 23 low 140 high.

09-10-2007, 04:46 PM
Low side:

The average evaporator pressure should be 30psi. Yours is averaging 36.5psi. Refrigerant pressure and temperature are almost identical in that pressure range which means your evaporator temperature is averaging 36.5 degrees. Average evaporator temperature should be just under freezing to produce the coldest air possible without turning the evaporator into a block of ice! To get colder air from the registers, the clutch cycling switch should be adjusted or replaced.

High side:

Your high side pressure apprears to be too low, which could mean the system is low on refrigerant. Keep in mind that ambient temperature and humidity have a direct effect on high side pressure. There is no way to tell how much refrigerant is in the system unless the system is drained, evacuated, and recharged with the proper amount of refrigerant. Only then can you accurately evaluate the compressor, conderser, and overall system performance. Don't skip the evacuation step. It is just as important as charging the system.

09-10-2007, 05:55 PM
Clutch cycling switch?

Was about 87* with 78 to 89 humidity

09-10-2007, 06:34 PM
The clutch cycling switch is located on the accumulator. There are two wires in the connector, (the system does not need to be drained to replace it). Removing the electrical connector exposes a small screw where a slight adjustment can be made. The adjustment will move the entire range, not a specific on or off pressure. When the system is fully charged, in a perfect world the cycling switch should energize the clutch at 42psi and shut it off at 22psi.

Ambient temp and humidity were both high during your tests. Drain, evacuate, and recharge the system. Close all windows and doors. Run the engine at 2,000 RPM with the HVAC mode switch in the Max A/C position and the blower on HIGH for 10 minutes, and then check pressures.

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