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AC compressor turns off when voltage drops and turns back on if I turn on lights

broley72

Full Member
Joined
Oct 22, 2012
Messages
14
Location
San Diego
At my wits end with this.
New battery, new alternator, new high pressure sensor.

So if I start the truck the AC is ice cold! Drive for a bit and notice the compressor turns off as the air gets warm. I look at the voltmeter and it is about 13 volts. Turn on the headlights and the voltage eventually goes back above 14 and the compressor kicks back on and it gets cold!
Engine control computer?
This is beyond my experience! Any help appreciated! :E:
 
Other recent updates: new AC fan unit, new plugs, Wires, rotors, fuel injectors, AC high pressure switch, new AC relay switch.
Also I returned alternator because it didn't fix problem. They tested my old one and it passed so I put old one back in. Both are 145 amp models.

I also had AC pressure tested and it only needed .2 lbs of freon.

I hope this helps!
 
What year do you have.
 
DId you check low pressure switch?
DId you cehck fan clutch wiring and belt?
 
I ended up selling the truck. It was an ?06. I suspect it was a malfunctioning ECC. Turning on the headlights to bring up the volts needed kicked the AC back on so I never spent the $300 to try the computer.
 
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