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Rawze · 05-10-2020, **(Subject: Compressor Inlet Temp sensor )**

(05-10-2020 )rapidisimo Wrote: Prostar CM871. Yes I get the codes once it overheats, coolant temp high and what not. I'll chk the ground voltage tomm.

You say fan is disengauging after air builds up but never comes back on.

1. Let air build up to full pressure.

2. Have a second person Switch key off in dash (or quickly head over towards the engine fan from outside the truck as soon as you turn key off). See if fan still turns freely immediately after engine completely stops. It should still free-spin for about 10-15 seconds or so after key-off until the ecm shuts down. When the ecm shuts down about 10-15 seconds later, you will also hear the fan solenoid switch off, and the fan should now be hard to turn when the air is released from it. - By the time you get to 1 minute after the key-switch is off, the fan should now be hard to turn again because the solenoid is switched off and ecm is shut down. If it is still free-spinning a minute or more later, then the fan solenoid itself is stuck open, or the ecm itself is not shutting off properly for some given reason (bad delete programming, etc.).

3. While air is still all the way up ... turn keyswitch on without cranking. Fan should release again and be freed up.

-- This will confirm the solenoid and fan clutch are both acting normally. Should also see if there are any audible air leaking from clutch or solenoid (or rest of truck) while your at it. This can be done by run engine to build air up all the way. Shut off keyswitch, and as soon as engine comes to a complete stop, turn keyswitch back to run position. - Walk around engine compartment and truck and listen for any air leaks while keyswitch is on.

Testing it with engine running: With the air all the way up and the keyswitch in the on position, engine running ... the fan should be released and free-spinning unless the A/C or coolant temp has it switched on. Simply unplugging the connector for the enigne fan solenoid should make in engauge, and plugging it back in should release it again.