A/C always on

[D_Fisher]

Just replaced my A/C evaporator core last weekend. I had the system pressure tested and recharged. I was driving around town last night, with the A/C off, and noticed that cold air was coming out of the vents. It was as cold as when the A/C is on. It seems like the A/C is running all the time regardless if it is supposed to be or not. I cant find any loose or unconnected wires. Any suggestions on what/where to check?

[cam98aro]

Re: A/C always on

is the compressor running?

[BLLDOGG]

Re: A/C always on

is the compressor running?

and are the ac lines cold to the touch?

[D_Fisher]

Re: A/C always on

The compressor is ON and the A/C lines are cold. The only way to turn off the A/C at the moment is to turn the turn the selector know to OFF. I checked all the plugs I disconnected when uninstalling the evaporator core and verfied that they were all reconnected. I am not sure what else to do. Suggestions?

I also noticed that the compressor is making a whirrr-whirrr sound. I think I forgot to add additional compressor oil when I installed the evaporator oil. I suspect that this is an unrelated issue to the A/C not turning off all together.

[CDNFB]

Re: A/C always on

There are only 3 positions on the enviroment control switch that the compressor will not be commanded to operate. They are:
1) OFF
2) floor
3) vents

For all other positions
1) A/C MAX
2) A/C
3) A/C bi-level
4) Defrost
5) Defrost bi-level
the compressor will operate.

Did you check to see if the compressor operates on the Floor and Vents setting?

Also, on my car ('99 FB) the compressor clutch is controlled by the PCM via a pressure sensor found installed on the high pressure refridgerant line just before the evaporator. The older systems used just a pressure switch in that location that directly controlled the clutch. Either way If I were you, this is where I would start looking.

If you changed the evaporator core, how did you re-charge the refridgerant? Did you use proper gauges? Improper pressures can cause the system to operate erratically.

[D_Fisher]

Re: A/C always on

I just must be an idiot. I have always driven around with the vent setting on defrost bi-level. That is where I had it the other day when I became concerned. On the drive to work today I turned it to floor and vent only settings. Sure enough the compressor turned off. I am slightl please that the original compressor is still going after 10 years/125,000 miles of constant usage. I probably keep the vent on floor or vent from now on so the compressor is not running constantly.

As far as re-charging the refridgerant... I took the car to a local A/C shop and had it professionally tested and recharged. Cost about $100 to test/recharge and $30 to strictly test.

Thanks for the help!

[cam98aro]

Re: A/C always on

I took the car to a local A/C shop and had it professionally tested and recharged. Cost about $100 to test/recharge and $30 to strictly test.

no offence, but that is EXPENSIVE.

i recharged my car myself for $30 (acually i did 2 cars)