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earnies2 · 04-08-2021, **(Subject: 2009 prostar A/C compressor stays running. Help )**

2009 prostar A/C compressor stays running even when I got the temperature knob on hot and the function knob on dash or floor.
I haven't used the truck for 9 months (motorcycle accident than covid) the freon leaked low due to a leaking Schrader valve, so I decided to also change the thermosters whal it was evacuated. After that I gassed it up its nice and cold but the compressor won't shut off, if I unplug the high side switch it shuts off the compressor when I plug it back in the compressor comes back on in about 15-30 seconds. Pressurs are good, fan kicks in at 325psi, compressor was changed last year . I'm stuck! Does the BCM turn the compressor off or does the rotary switch turn it off? Any help is appreciated. I have been down for 9 month's and barley holding on.
Thanks in advance

Waterloo · 04-08-2021, **(Subject: 2009 prostar A/C compressor stays running. Help )**

Is the engine fan running continually too? I'm thinking it is overcharged or it could possibly be a bad High Pressure switch, the one up at the radiator. I would also peel back the split loom from the wiring on the high pressure switch to check the integrity of the wires. Mine has broken twice on mine and repaired. Just off the top of my head, not the AC guru here, but those are two problems I have run into that sound similar to your situation.

Rawze · 04-08-2021, **(Subject: 2009 prostar A/C compressor stays running. Help )**

Could be bad humidity sensor... could be tarnished fuses in the fuse panel making for weak signal to something.

You have to look in the cab control module to see why it is on.

just things to consider any ways.

earnies2 · 04-08-2021, **(Subject: 2009 prostar A/C compressor stays running. Help )**

(04-08-2021 )Waterloo Wrote: Is the engine fan running continually too? I'm thinking it is overcharged or it could possibly be a bad High Pressure switch, the one up at the radiator. I would also peel back the split loom from the wiring on the high pressure switch to check the integrity of the wires. Mine has broken twice on mine and repaired. Just off the top of my head, not the AC guru here, but those are two problems I have run into that sound similar to your situation.

No the engine fan is not running i will peal back the covering and check it in the morning. How would it being overcharged keep the compressor running when I'm calling for heat.

earnies2 · 04-08-2021, **(Subject: 2009 prostar A/C compressor stays running. Help )**

(04-08-2021 )Rawze Wrote: Could be bad humidity sensor... could be tarnished fuses in the fuse panel making for weak signal to something.

You have to look in the cab control module to see why it is on.

just things to consider any ways.

Whare is the humidity sensor?
I will check all the fuses. I looked at all the relays and I didn't see a a/c compressor relay. Is the compressor controlled by the Body control module or the controls on the dash?

Rawze · 04-09-2021, **(Subject: 2009 prostar A/C compressor stays running. Help )**

(04-08-2021 )earnies2 Wrote:
(04-08-2021 )Rawze Wrote: Could be bad humidity sensor... could be tarnished fuses in the fuse panel making for weak signal to something.

You have to look in the cab control module to see why it is on.

just things to consider any ways.
Whare is the humidity sensor?
I will check all the fuses. I looked at all the relays and I didn't see a a/c compressor relay. Is the compressor controlled by the Body control module or the controls on the dash?

Prostars get plagued with ghost problems when the fuses in the panel get tarnished/discolored. This happens even if none are actually bad. ref: http://rawze.com/forums/showthread.php?t...1#pid12861