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Jim Grant's Tech Tips
'99 Pontiac, Grand Prix, No Cooling Fan & No Heater Fan
Q:
The
cooling fans on my '99 Pontiac Grand Prix with a 3.1 aren't working. The
car gets warm when it is sitting and idling. Also, the heater doesn't
work (there's heat but no fan) can you help?
- Sean
A:
I
doubt that the two conditions are related. The heater has two fuses one
marked HVAC Hi, which is a 30-amp fuse, and the other HVAC CTRL has a
20-amp fuse. If the HVAC Hi fuse has failed you'll have all blower speeds
but high. If the HVAC CTRL fuse has failed you'll have no blower function
at all. Your vehicle is equipped with two cooling fans for the radiator
and each fan has its own fuse as well. The cooling fan fuses are located
in the Underhood Accessory Wiring Junction Block. You'll find the fuses
marked COOL FAN 1 & COOL FAN 2 and both have 30amp maxi fuses. If
you perform your testing you'll find that both of the fan fuses will have
electrical power to them at all times. To add to the fun there are three
relays for the cooling fans that the vehicle computer controls. One of
the quickest checks for cooling fan operation is to activate the A/C system.
The computer should respond by turning one or both of the cooling fans
whichever the program deems necessary. Also, be aware that it is not uncommon
for a temperature gauge to move up to the ¾ mark or greater before
the cooling fans are commanded on by the computer. Coolant temperatures
over 240 degrees are not uncommon before the cooling fan is activated
and is not an overheat condition. If you've covered the basics, fuses,
connections, etc., you may want to have a technician with diagnostic equipment
(like a scan tool) dig in and diagnose the problem. Once you know the
cause the solution becomes the easy part.
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