YakkoWarner
Full Access Member
- Joined
- May 29, 2024
- Posts
- 130
- Reaction score
- 132
- Location
- Central Texas
- First Name
- Wolf
- Truck Year
- 1989
- Truck Model
- R2500 Suburban
- Engine Size
- 454
My 454 truck has the same fan. It runs all the time as soon as the key is turned to ON. From this thread I’m guessing something isn’t right with that?
The thermal switch is on the passenger side of the engine (single wire) - if the wire came off and is touching metal somewhere, it will trigger the fan to come on. If the wire isn't just hanging loose, try unplugging it from the switch and turn the key on; if the fan stopped than there is a good change your thermal switch is shorted and needs renewal. If the fan still runs, check its relay over on the driver side inner fender area. That could be stuck closed as well.
Normal operation is independant of the A/C - mine comes on anytime I'm in traffic - seems like the threshold is around 160-170 degrees and it will click on.