A/C always running?

[blackhawk60]

Any time I have the HVAC on whether the heat is on or the A/C is on, I shut down the car and I can hear the A/C lines hissing or as if I had the A/C on. The line that comes from the back to the front is covered in frost. I don't think this is normal when the A/C is not turned on intentionally is it??

 

[projectSHO89]

If you have an automatic system (you didn't specify) the AC runs whenever the system is not in VENT, or OFF, depending on the ambient temp.

If the low pressure line is covered in frost, you are likely low on refrigerant charge. Have it checked.

The hissing noise is due to the refrigerant equalizing pressure between the high and low sides of the system after the compressor is disengaged. Normal for the most part but is usually not noticed.

Steve

 

[blackhawk60]

So if I have the temp set @ 75deg with the def/flr setting and the fan midway, the a/c system continues to run?

 

[LaTechSHO]

any time the defroster is on the a/c clutch is engaged.....


so yes, in that instance your compressor should be working


Louis

 

[blackhawk60]

Well, then it looks like I have a leak in the system because it was just filled back in Feb.

 

[rangerj]

AH60,

Look for black oily wet dirt at any and all A/C couplers (joints), on the front of the condenser core, behind the glove box on the evaporator core (rare), behind the A/C clutch pulley for the compressor shaft seal, and around the schrader valves and the attached pressure switches for signs of leaks.

The condenser in the Northeastern states get pin holes in them from the corrosion salt causes to the aluminum core. The condenser also gets small pinholes in it from object strikes, like stones thrown from truck tires.

The primary place for leaks is at the connections. rangerj

 

[projectSHO89]

You will need to hook up guages to determine the true state of charge of the system.