whats going on here? everytime i drive some where all my windows get really foggy. and i have to keep my heater at 90 deg and fans on max just too keep warm. on clubgp i was reading a post and they said possibly heater core? what do u guys think?

Turn your AC on to dry the air. It'll remove the moisture from the inside of the car when the compressor is running. If that doesn't work, do the evap core cleaning in Techinfo.

Hmmm.. If he is in Michigan then he is probably experiencing the same artic cold we have here in NY. And I'm 99% sure that the compressor is disabled below a certain temp (45F I think) to keep the heater core from freezing, so no air drying effect there...
Good point about cleaning the coil. That would help the volume of air output.
A leaking heater core will result in hard to clear windows, had that happen in my 92 Achieva last year. You will also notice the occaisonal whiff of anti-freeze, especially when you first turn on the blower fan. Might also account for a lack of heat if the heater core was clogged (which usually goes along with corrosion and a leak). Any idea if the antifreeze was changed in the past?
Also worth noting is that water in the padding below the carpet or in the trunk will tend to fog the windows after you have been driving a bit and the interior of the car warms up (with the windows ice cold lately).
If it'* a heater core then there'* not much you can do besides a new one, unfortunately I have never changed one in a Bonneville. If it turns out that it'* water in the rug new seals are the long term fix, for a short term fix you could throw a small cube heater (set on low heat, high fan) into the car, crack all 4 windows a small bit and let it run overnight. That should get a lot of the humidity out of the car.

Rob

Ya, what rdusel said.

Do you smell coolant inside the car? My heater core went out back in May time frame at 75K. The car would reek like coolant everytime you had the heat on. Since it went out in the spring, I'm not sure if the heat was weaker.

I took it to a shop to have it replaced because it'* behind the glove box (too involved for me) and he said it was common for them to go out on H-bodies. I dunno, though, because I haven't heard of many going out here.

i dont smell any collent.

It could still be clogged. You could try a coolant flush.

Whats the problem here, are you having problem with air flow? Try hitting the MODE button until you get air coming out of the vents. Turn the blower on high. Do you get a lot of air? If so the evaporator isn't your problem.

Could be your air mix door....does your climate control blink when you first turn on the car for a few minutes?

I have the same problem with my 97 se....its caused by shrunken door weatherstrips,leaky rear glass around the moulding...and also the ton of water that enters the trunk whenever you open it in the rain.

the heat work it just not very hot and it doesnt blow that hard im not sure if its just cuz its an electronic climate control cuz the manual ones for some reason blow harder. and what ever is going in it causeing my windows to get really foggy and really fast and i have to have the heat maxed and the blower maxed just to keep somewhat warm so in other words my heat sucks and my car gets really foggy im gonna try that cleaning the heater core then go from their.

hey l27buick, our 95 bonne was the same way when we got it 2 months ago. changed the thermostat(180), had a 195, and the heat is great. after warmup only need low to mid range fan setting and temp of 80. might work, cheap enough to try.
cory