AC compressor starts automatically even if AC is OFF.

Tiny
MUHIB_J
  • 2008 MITSUBISHI LANCER
  • 55,000 MILES

When I start my car and keep for heating, sometimes I hear a noise of trip and compressor starts, and clutch (below the belt) also start rotating.
Is this normal even if AC buttons are oFF in the car.

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Monday, August 29th, 2011 AT 6:31 AM

5 Replies

Tiny
KHLOW2008
  • EXPERT
  • 41,949 POSTS

This is not normal for your vehicle according to specifications as stated in our database. If the A/C switch is not turned on, the compressor should not engage.

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Monday, August 29th, 2011 AT 2:14 PM
Tiny
MUHIB_J
  • MEMBER

Thanks for the reponse.
Please let me know how to solve this AC problem.
What checkups do I need to do or what to be replaced.
Regards.

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Friday, September 2nd, 2011 AT 3:28 PM
Tiny
KHLOW2008
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Is your A/C system manual or automatic control?

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Friday, September 2nd, 2011 AT 5:26 PM
Tiny
MUHIB_J
  • MEMBER

AC system is automatica I guess. Please tell me what to do to sort the problem. Also let me know if it is manual thn wat to do.

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Tuesday, September 13th, 2011 AT 8:56 AM
Tiny
KHLOW2008
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Whether manual or automatic system, the A/C compressor gets its power supply from the A/C compressor relay and there are 3 possibilities for the relay to be energised.

1. Faulty relay. It is self triggering intermittently and contacting to provide power to the compressor. Try swapping out the compressor relay with the fog light relay and see if problem goeas away.

2. A short in the grounding circuit of the compressor relay. You would need to test orange wire for shorting.

3. Faulty PCM. It is grounding the relay intermittently.

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Tuesday, September 13th, 2011 AT 12:00 PM

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