defroster

sonoma driver · April 23, 2005

I am driving and I have the defroster on. The windows do not fog up when i do this. But when I turn the heat up slightly from the lowest cold temp where it has to stay at so it doesnt fog up. Anyone else have this problem? its annoying that its spring and some days are cold and i can not put the heat on unless i have to stick my head out the window.

I have tried looking in my maintenance book for the defroster but I can not find anything about it like they skiped it or something.

sonoma driver · April 23, 2005

I think I know the problem which is the ac does not go on below 40* and that causes just the heat to come out the vent and not dry the air before it hits the window. IF I am right is there anyway to get around it?

mcreyaufmiller · April 23, 2005

check your compressor, mazke sure it is working correctly.

mmmikkke · April 23, 2005

I think you're heater is adding humidity to the air, I'd suspect a leak in your heater core. Notice any wet carpeting where it shouldn't be? That would be a sign.

Also would matter if your coolant is disappearing out of your recovery tank.

sonoma driver · April 24, 2005

no wet spots and the reserve tank stays at a constant level

mmmikkke · April 24, 2005

no wet spots and the reserve tank stays at a constant level

<{POST_SNAPBACK}>

So water's getting into the heater area somehow, and it's only evaporating into your defroster air if you have the temperature control in any position other than full-cold. I'll admit, I'm baffled.

This is a long shot...maybe you live in a humid climate and you use your air condo occasionally to take water out of the air...so if the drain is plugged, and the water removed from the air can't get out, it's just sitting there waiting for a chance to evaporate and that happens when you run the heater without the a/c.

Sorry, that's all I have left for ideas.

If my guess about the humid climate is right, you should be able to confirm that your drain is working, by noting the dripping from the passenger-side firewall onto the pavement below, when it's humid and you are running the compressor. If you leave your truck parked and run the compressor for 5 minutes, there should be an obvious drip...drip...drip coming out of the drain.

The compressor runs when you have the a/c control set to defrost, as well as when you are asking for cooling.

The drain looks like a rubber hose tip sticking out of the passenger side of the firewall, down low in the engine compartment. You could carefully send a wire/pipe-cleaner up into that rubber hose an inch or two to see if it's plugged. If plugged, it shouldn't take much to unplug it. It will probably be just lint or perhaps decomposing leaves, and the plug should dislodge with very little force. And if you dislodge the clog, you should see water dripping out immediately.

So be careful--use a very light touch--because your air condo evaporator coil (looks like a small radiator) is also at the other end of that rubber hose. You wouldn't want to puncture it or your current fogging problem would become a much more expensive evaporator replacement problem.