Radiator Cooling Fan Motor: Description and Operation

On models equipped with electric engine cooling fans, the battery ground cable should be disconnected whenever underhood service is performed.




1985 BUICK ELECTRA, PARK AVENUE & OLDSMOBILE NINETY-EIGHT

DESCRIPTION
On gasoline engine equipped models less heavy duty cooling, a single two speed fan is used for cooling purposes. On gasoline engine models equipped with heavy duty cooling and all diesel engine models, dual cooling fans are used. On models equipped with dual cooling fans, the left side fan has two speeds while the right side has one speed and only operates when the left side is running in the high speed mode. The on and off operation of the cooling fan(s) is controlled by the Electronic control Module (ECM), while the fan speed and mode of operation are controlled by vehicle speed, engine temperature, A/C head pressure and transmission converter clutch operation.

Fig. 6 Electric engine cooling fan wiring diagram. Buick Electra, Park Avenue & Oldsmobile Ninety-Eight with V6-260 diesel engine:

Diesel Engine Models
1. If coolant fan motor does not operate, check the following:
a. Check for blown fuse, Fig. 6.
b. Check for blown fusible link.
c. Connect jumper wire from one of the cooling fan relay coils to ground. Cooling fan should run.
2. If fan motor operates whenever the ignition switch is in the Run, Bulb Test or Start position, check the following:
a. Dual temperature switch and A/C high pressure switch to see if any contacts are closed at all times.
b. Coolant fan relay for stuck contacts.