AC compressor starts by itself!

Hi, I have a 1999 Dodge Stratus, 2.5 v6 and the AC starts by itself when the switch is OFF.
When I start the car everythin is normal for abor 20 seconds, after that the AC system (compressor, et al) start running (very noisy) for about 30 seconds, then it stops. During normal car run the AC starts and stops sometimes, something about 20 seconds every 5 minutes.

I disconnected the AC plug and of course it stopped doing the noise. May be it’s a relay or the BCM, I have all the car manuals but I don’t have the DRB III Diagnostic Tool (very expensive).

Anyone with this problem in the community??

Best regards,
ERnesto Silva.

Is your defroster on? Most defrosters kick on the A/C to put dry air on the windshield

OOOhhhh, that may be the problem. When I bought the car about a year ago the defrost light/switch gets on by itself sometimes at car starting. I’ve just checked the blower channels knob and it was at the “defrost” section (windshields).

Next Saturday I’ll connect the compressor again and see what happens.

As you suggest it may be the defrost control, maybe a relay or the body control module, I will check the manuals and see if something appears.



Some older cars like my 99 Corolla automatically turns on the A/C when the control is set to defrost.

Perfectly normal if any defrost setting was selected… As the others have mentioned.