Buick Repair Questions? Ask a Mechanic for Answers ASAP
Hello & Welcome,
Can you tell if the cooling fans are coming on at all (like when the AC is switched on?
OK - thanks.
Let me send along the schematic of the system so that you can do the basic tests first. That would be to check (with the meter) that the fuses are OK. Make sure power is making it to both sides of each fuse as the test.
Your plan to apply power and ground directly to the fan motor connectors is a good one, to make sure that each fan works.
As you might be able to tell, the PCM is what controls the relays, which in turn control the fans. I will also see if I can grab the description of the system and send it to you.
Please let me know what you find.
Here is the description of the system.
The electric cooling fans are used to lower the temperature of the engine coolant flowing through the radiator. They are also used to cool the refrigerant (R-134a) flowing through the A/C condenser.
The electric cooling fan operates when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is controlled by the powertrain control module (PCM). The PCM turns the cooling fan ON by grounding the coil of the cooling fan relays when certain conditions are met. When the A/C is requested, the cooling fan will also be turned ON.
Power for the cooling fan motors are supplied through Maxifuses®. The cooling fan relays are energized when current flows from the fuses in the Underhood Accessory Wiring Junction Block , and through the relay coils to ground through the PCM. The Low Speed fans control circuit is grounded for low speed fans operation. During low speed fans operation, both fans run at a slow speed. The High Speed fans control circuit is grounded for high speed operation. During high speed fans operation, both fans run at high speed.
I hope this helps. Please let me know if you need more information.