2004 Honda Civic

2004 HONDA CIVIC
46,700 MILES • 4 CYL • FWD • AUTOMATIC
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MAURILIOSANCHES
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  • 4 POSTS
a/c clutch not working when a/c switch is on
May 25, 2010 at 12:34 PM
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KHLOW2008
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Hi mauriliosanches,

You would need to check if there is battery voltage at the AC clutch. If no power is available, then you need to check the compressor clutch relay.

Are the cooling fans turning on when the AC switch is operated?
May 28, 2010 at 12:37 PM
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MAURILIOSANCHES
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  • 4 POSTS
There is no voltage in the A/c Clutch. Also the cooling fan is not working.
I think the Ecu is bad or the multiplex , but I do know how to test them...
May 30, 2010 at 8:11 PM
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KHLOW2008
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Check for power supply to the ac clutch relay.
May 31, 2010 at 9:22 AM
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MAURILIOSANCHES
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Already checked. There is power, all the fuses are ok, The computer is not sending the signal to the a/c relay. (all wiring connection are good!)
May 31, 2010 at 1:44 PM
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KHLOW2008
  • CAR REPAIR CONTRIBUTOR
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If the relay is not being grounded to activate the compressor, the mostlikely fault would be the PCM. This is a known problem.

At the PCM, use a test lamp to back probe the E18 terminal ( clutch relay, RED wire ) and if the compressor comes on, the wiring is ok and you have a faulty PCM.
May 31, 2010 at 2:23 PM
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MAURILIOSANCHES
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Yeap. The Pcm/ECU is not sending the ground.
Thanks a bunch.
May 31, 2010 at 3:06 PM
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KHLOW2008
  • CAR REPAIR CONTRIBUTOR
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You're welcome.

Glad to know you have found the solution.

Have a nice day.
May 31, 2010 at 3:58 PM