Pontiac Grand Prix 2003 Heater Problem

I have a 2003 Pontiac Grand Prix GT with 3.8 L engine. It is 138K miles. I am having some electrical problem for sometime.

First the display for the radio/clock went out (it does display very infrequently). I thought that I can live without it. So didn’t do anything to fix it.

Then the fan stopped working for position 1 and 2. Other positions 3, 4, 5 works. So I told myself that okay I will manage with fan speed 3 or 4. So didn’t do any fixing.

Now I find that the heat is not avilable. The AC still works well. Now winter is on its way and I can’t live without heat in the car. I am wondering what could be the problem and what I can expect to spend.

Any help?

Just take the car into a shop and have it looked at. Given what you’ve just said I’m sure its your best bet.

The fan speed, or even if the fan works doesn’t have anything to do with whether or not the car can produce heated or cooled air.

If it doesn’t produce heated air then you either have a cooling system problem (such as a bad thermostat) or perhaps a problem under the dash with the control of the heated/cooled air (such as a bad blend door).

I’m betting the blend door!

[b] I'm betting the blend door![/b] 

Me to.  

I will forecast that the other fan speeds will be going out over the next few months.  They are resistors burring out. Not expensive part wise, but some are not easy to get to.

Thanks for your suggestions. Here is some more details. The clock/radio display is not working (thought once in a while display does show up) for more than 3 years. The fan has not worked in position 1 and 2 for at least last two years.

Should I go to the dealer for this problem or a local mechanic will do?


I took the car to a local mechanic. The heater core was blocked. So the core was reverse flushed with a garden hose and the coolant was drained and replaced ( cleaned with water first and then Dexcool). The heat is working but looks like sluge build up is not all clean. I am thinking about getting a power flush in amonth so that the sluge is clean. My local mechanic who doesn’t have power flush says that I come back to him for another flush (again water few times and then Dexcool). Any suggestion if power flush (so only one flush but at high pressure) is the way to go or several drain and flush at local mechanic. Please advise.

The blower motor only works at 3,4,5, max but doesn’t work at 1 and 2. A firend suggested that I need to replace blower motor resistor. I have seen the posting and they say replace this resistor when the blower only works at full speed. In my case it workds for some intermediate speeds as well. Any advise?

It is almost certainly the blower motor resistor. There’s a small chance that it is the fan switch itself, but that kind of problem is more rare. Blown resistors are common, and its not all or nothing. You can easily lose 1 & 2 while still having 3 & 4.

If you have a voltmeter and can use it you can test the switch. But if you don’t, the resistor is probably not very expensive and is a good bet.