valderickd Posted September 25, 2011 Share Posted September 25, 2011 Ac system full and new but compressor wont come on. Any help will be greatly appreciated. Quote Link to comment https://www.bigmacktrucks.com/topic/20755-1999-ch-ac-issue/ Share on other sites More sharing options...
41chevy Posted September 25, 2011 Share Posted September 25, 2011 First check your fuses and you may have an AC relay, check that also. If all there is good, than got to the next step.With the key on, engine off, turn on the Ac and put the blower on, use a test light or meter at the wires at the Compressor clutch to see if there is power there. If the is, the magnetic clutch should be engaged. You can have somebody turn the AC on and off and see or hear the clutch engage, and you should not be able to turn it. If it is not engaged and you have power then most likely the clutch is bad. If you do not have power, then follow the AC lines back to the low pressure cut out switch, check for power in and power out ,while the truck is running with the ac and blower on. If you have power in and none out, jump the switch, if the compressor engages it it a bad Low Pressure switch. If no power there then I would head to the AC/Heater controls in the dash for a bad switch or wire connector. There may be a few other items I missed, but these are the basic checks for most every system. Paul Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/20755-1999-ch-ac-issue/#findComment-86920 Share on other sites More sharing options...
valderickd Posted September 26, 2011 Author Share Posted September 26, 2011 Thank you very much. I will check relays and fuses in the morning. I will keep you posted. Quote Link to comment https://www.bigmacktrucks.com/topic/20755-1999-ch-ac-issue/#findComment-86964 Share on other sites More sharing options...
shortstack Posted September 26, 2011 Share Posted September 26, 2011 High pressure switch too. Seen the wires break on those. Trey Quote Link to comment https://www.bigmacktrucks.com/topic/20755-1999-ch-ac-issue/#findComment-86966 Share on other sites More sharing options...
41chevy Posted September 26, 2011 Share Posted September 26, 2011 High pressure switch too. Seen the wires break on those. TreyGood point, could be over charged from the get go. Paul Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/20755-1999-ch-ac-issue/#findComment-87003 Share on other sites More sharing options...
a5redwing Posted October 9, 2011 Share Posted October 9, 2011 (edited) One more thing, I've had the fan blower switch go bad. The fan would blow but would not have any a/c in high or low just in medium. Replaced the switch and all was good. And make sure all wiring harnesses are plugged up. sometimes its the stuff that makes you feel dumb. Edited October 9, 2011 by a5redwing Quote Drew Link to comment https://www.bigmacktrucks.com/topic/20755-1999-ch-ac-issue/#findComment-88041 Share on other sites More sharing options...
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