Where are the cooling fan relays for a 1998 Cadillac Deville Northstar located?

SENSOR ON NORTHSTAR V8 IS ON DRIVERS SIDE OF MOTOR RIGHT ABOVE TRANSMISSION. COOLING FAN RELAYS ARE UNDER FANS ,IN MIDDLE OF LOWER CROSSMEMBER

The fans /fans are turned on by the pcm, using input from the coolant temp sensor, as well as the HVAC system. The cts is on the right rear of the engine below the egr valve.

Check the fan to see if it is going on. On my 1997 Cadillac Deville Limousine I had to have the 2 fans, and 3 relays replaced, as well as the wiring contacts for the relays at an auto electric shop for about $700 last fall, but it has been running cool since then.

The only other things would be the coolant temp sensor or the engine computer. Alot of the new GM's have the on and off function of the cooling fans controlled by the computer. If the coolant temp sensor is ok, then most likely the problem is in the engine computer.

The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.
If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.
The hose goes in to the engine to a crossover and comes out the other side close to the thermostat housing,the blockage may be there.

There are three cooling fan relays in the fuse block under the hood.




The fan relays above are numbered 37,39 and 40

Relay 37 is RH fan
Relays 39 and 40 are LH fan.


You can check if your fans are working by switching on the air con.
Are you having overheating problems?

Regards.

If for the heater it is a blower module on top of the evaporator core housing. If for the cooling fans it is inside the front fender behind the headlights. That is a module also tice the size of a normal fist

check relays located under back seat. u should have a cover that tells you witch one is witch and where

Left Hand Side Of Engine Compartment On Relay Bracket