A/C clutch not working

Tiny
EL CHINO
  • MEMBER
  • 2005 KIA SPECTRA
  • 2.0L
  • 4 CYL
  • 156,000 MILES
When bypassed with a wire it works and it blows cool air.
Thursday, September 16th, 2021 AT 9:53 PM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
I assume you are bypassing the relay with a wire or are you jumping straight to the compressor?

I assume you are jumping 12 volts directly to the compressor which means we have an issue with the control side.

This means the PCM, control module, wiring, or relay are the issue.

So we need to start with checking voltage at the relay on each of the pins with the key on and A/C on.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Basically we need to have 12 volts on both pins from each fuse and then you need to check and make sure the PCM is grounding the relay in order to close it and turn the compressor on.

You do this by putting your red meter lead on battery positive, and the black lead on the terminal from the PCM of the relay with the relay removed.

With the A/C turned on your meter should read 12 volts. If it does then the PCM is grounding the relay and your relay is the issue.

If it is not then we have a PCM or something else telling the PCM to not ground the relay like a pressure sensor or aircon module.

However, that is less likely so let's start with this info and go from there. Thanks
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Friday, September 17th, 2021 AT 1:04 PM

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