My defroster used to work great. It would clear up moisture on the inside front glass in less than a minute. It's not a blend door problem, the air blows fine out the winshield ports/vents, but I'll double check the blend door function tomorrow by puling the glove box and watching the door cycle.

The problem is that it's not pulling the moisture out of the air like it used to. I had a shop I trust check the A/C system and they said everything was OK, just a little low after 10 years (2001 HO 6 speed). They added some juice and said it was fixed, but it's still broken, just not as bad.

The only way it will defrost the windshield is if the temp control is set to full cold (burrrr!). If I turn it to warm or hot I get steam out the vents and she fogs up fast.

I'm thinking a leaky heater core, anyone been down this road?

 

Usually if the heater core is leaking you will smell antifreeze and it will leave a bit of a greasy film on the window.

 

could also check the heater box drain to make sure all the water is getting out

 

If it doesn't smell of antifreeze I would run a wire thru the drain plug on the firewall in front of the heater core evap area.

Another item is oustide temp/humidity and dew point conditions. These weigh in on my trucks defroster efficiency, especially during warm up.

 

Thanks guys,
I did notice a bit of a smell when steam comes out the defrost vents when turning the temp control to hot. The window does not wipe clean easily after fogging up even though I have already cleaned it with glass cleaner. I have already cleaned out the drain. I think it's worth a shot at this point to swap out the heater core. I've read up on the posts about digging into the dash to get to the core, sounds like a fun job.

 

Boy, that REALLY sounds like a heater core to me.

 

Just wanted to say thanks for your help. Swapped the heater core and now defrost is working like new again. Not a fun job by any standard, but it's dooable. The posts and pictures by other menbers made it alot easier than following the FSM, believe it or not