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Jim Grant Tech Tips Jim Grant Tech Tips
A collection of helpful articles based on reader submissions
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Below is a collection of Jim Grant's Tech Tips sorted by Vehicle Make. These Tech Tips were answers to questions submitted to Jim by users over the course of many years.
If you have any questions, please feel free to email us.



Lincoln - Mercury
  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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