Fans?
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Fans? (CENTURION)
The aux fan switch in the block between #1 & #3 plugs has exclusive control over the front fan through the aux fan relay on the left side of the radiator shroud; the ECM has exclusive control over the rear (main) fan and only over that fan through the main fan relay on the rear of the left inner fender well.
It sounds as though you have a problem with the main fan control. Try this: 1. Open the A/C pressure switch connector near the blower motor housing, start the engine and the main fan should come on immediately. If so, replace the coolant temp sensor in the top of the block under the TB.
2. If not ground the grn/yel wire at the main fan relay and the main fan should come on. If so wring out the wiring from the ECM to that relay.
3. If not, open the connector at the fan, ground one fan motor terminal and tap a jumper from the other terminal against the battery + lead and the fan should run. If so, replace the main fan relay.
4. If not replace the main fan motor.
It sounds as though you have a problem with the main fan control. Try this: 1. Open the A/C pressure switch connector near the blower motor housing, start the engine and the main fan should come on immediately. If so, replace the coolant temp sensor in the top of the block under the TB.
2. If not ground the grn/yel wire at the main fan relay and the main fan should come on. If so wring out the wiring from the ECM to that relay.
3. If not, open the connector at the fan, ground one fan motor terminal and tap a jumper from the other terminal against the battery + lead and the fan should run. If so, replace the main fan relay.
4. If not replace the main fan motor.
