Without Air Conditioning

OPERATION
Voltage is present at the contacts of the cooling fan hi speed relay at all times through the cooling fan fuse link cartridge.

With the ignition switch in "START" or "RUN", voltage is present at the coils of the cooling fan relay and the cooling fan hi speed relay through the engine fuse. With the cooling fan hi speed relay deenergized. Voltage is also present at the contacts of the cooling fan relay.

If engine coolant temperature reaches 207 degrees F, the fan coolant temperature switch closes, grounding the cooling fan relay coil. The relay contacts close and power flows through the cooling fan fuse link cartridge, the cooling fan hi speed relay (deenergized),the cooling fan relay, and the low speed winding of the electric cooling fan to ground. The fan runs at low speed.

The fan will run at low speed until: a) the cooling fan relay coil is no longer grounded and the fan shuts off, or b) the engine coolant temperature reaches 221 degrees F and the hi fan coolant temperature switch contacts close. If the hi fan coolant temperature switch contacts close, the coil of the cooling fan hi speed relay is grounded, energizing the relay and switching current flow from the cooling fan relay contacts to the high speed winding of the electric cooling fan; the fan runs at high speed.

When the fan coolant temperature switch is closed, a "fan on" input is provided to the Powertrain Control Module (PCM).