AC not staying on

2003 FORD EXPEDITION
250,000 MILES • 5.4L • V8 • 4WD • AUTOMATIC
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JASON HERMAN
  • MEMBER
  • 2 POSTS
The clutch on my AC compressor will engage when i start my truck up but after about thirty seconds it will stop and not come back on until i turn my truck off and back on again. it repeats this never staying on. i charged my system hoping this would fix it but it did not. if i run the compressor right to the battery it will stay on until i unplug it.
Jun 3, 2019 at 5:30 PM
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KASEKENNY
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 18,907 POSTS
Hi Jason,

Good job applying battery voltage and confirming it works. If you look at the wiring diagram you are basically taking the place of the PCM and then the two relays. The way this works is the PCM applies voltage to the clutch field to pull the clutch in and turn the compressor. The fact that it runs, shows that they are at least intact but I am concerned that as they heat up they are having an issue. So we need to check the relays just to eliminate them or we will be chasing our tail.

Assuming they are okay then either the PCM is shutting it off and is the issue or the PCM is seeing a sensor that is telling it to shut it off.

Do you have any codes in the computers? If there is a code the PCM could be shutting it off as a protection mode so any DTCs will hopefully point us in the best direction. If you can't pull codes, any parts stores these days will get them for you.

Let me know about the relays and the codes and we can go from there.

thanks
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Jun 3, 2019 at 8:11 PM
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JASON HERMAN
  • MEMBER
  • 2 POSTS
Only codes are multiple misfires.
Jun 3, 2019 at 8:55 PM
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KASEKENNY
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 18,907 POSTS
Have you checked your AC pressures with a gauge? The dual gauge set can be rented from most parts stores. They make take a deposit but return it when you return the tool.

We need to see what the pressures are with the compressor off and then what they are when it kicks on after a start.
Jun 4, 2019 at 6:41 PM