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Old 08-05-2012, 07:24 PM   #16
hatzie
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Join Date: Oct 2008
Location: Wentworth, NH
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Re: A/C blowing fuses

Quote:
Originally Posted by gchemist View Post
I have not checked heat or DEF. I'll check this afternoon. Definately not on Vent. As soon as I move from vent to A/C it blows.
The fuse blows with the clutch unplugged. So it's not the clutch electromagnet.
If it's not blowing on VENT then it's not likely it's your heater fan.

Test the AC wires for a short or a damaged TVS diode at the compressor connector with a DMM;
  • Switch off the ignition.
  • Unplug the low pressure cutout switch and tie the the connector up
  • Unplug the compressor and tie the connector up as well.
  • Switch the dash control to VENT.
  • Set your DMM to Resistance.
  • Test the Compressor clutch TVS Diode by hooking your meter leads to the compressor connector leads and checking for a short then reversing the leads and looking again. It should show an open circuit in one direction and dead short in the other. If the meter shows a dead short no matter which way you hook up the meter leads the TVS diode is blown.

If the TVS Diode tests OK test the clutch feed wires.
  • Hook one lead to a good engine ground close to the low pressure switch connector and verify 0 ohms dead short to the battery negative post.
  • Move your DMM lead from the negative battery post to the Dark Green wire terminal in the Low Pressure cutout plug.
  • Your DMM should read infinite resistance "0.L" or "1 . ". If the meter reads an actual value you've found your short. If not Start over with the Light Green wire.
  • Physically check the offending wire for damage and repair it.
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RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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