Heating problem in 2002 Grand Prix

I recently noticed that my heater takes much longer to heat up, and once it does, the temperature will flucuate between hot and cold. I also notice that the blower is more forceful when the temp is set to cold than when set to hot.

I recently replaced the resistor when speeds 1 & 2 were not working, but that shouldn't impact the temp of the heater, right?

Living in Michigan, I can't drive this car much longer w/o consistant heat. Any ideas? Why does my heater flucuate between hot and cold?

Thanks.

Welcome to AF.

It would help to post what engine or model GP you have and which climate control system. Manual, manual dual zone or automatic climate control (ACC). Check the thermostat. Sounds like it may be stuck partially or fully open.

The GP is a SE w/ manual dual climate control. If the thermostat is open or stuck, can someone post instructions to fix?

Thanks

3100 engine? Also have you checked coolant level? Not exactly easy to replace on the 3100 engine like the 3800. Located under the throttle body at the left hand side of the lower intake manifold. There is an exhaust cross over pipe with a heat shield in the way. With the right tools and patience it can be replaced DIY.

I agree with Bob that it could be a t-stat if you're not losing coolant. IF you are losing coolant, you could have the infamous intake gasket leak (3100 engine) or UIM/UIM gasket failure (3800 engine).

Your heat fluctuates due to the t-stat not regulating coolant temp properly (if your coolant level is fine) or due to air passing through the heater core (if you have a coolant leak).

You live in my area (I'm in Flint, MI), so if your coolant level is dropping and you don't have the mechanical ability to do the intake/UIM job yourself, PM me and I can suggest some good shops/mechanics in the area that won't bend you over.