defroster question

[redlobster84]

I work third shift and usually drive home about 715am, lately the temp has

been around low 40's, high 30's. Whenever I use the heater ( I know that

heat will only come out the floor or defrost vents) , I usually just keep it on

the defrost vents. The car will fog up extremely quick and I have a very hard

time seeing out. I can set it on fresh or recir setting and set the fan speed

on the highest and it just clears out a section on the lower windshield. The air coming out is hot like it should be.

I have a 92 festiva ,5psd. It is blowing out enough air, just don't know if there is a trick to defrosting correctly. Should the a/c

switch be pushed in so the light comes on ? Any help is very appreciated.

[perucho]

Warm air can hold more humidity than cold air so when it hits that cold windshield, it will fog up. You need to have the a/c running to dry out the air (when it goes through the a/c condenser instead of your windshield) when you use the heater. It depends on vapor pressure but that may be too much info

[redlobster84]

Warm air can hold more humidity than cold air so when it hits that cold windshield, it will fog up. You need to have the a/c running to dry out the air (when it goes through the a/c condenser instead of your windshield) when you use the heater. It depends on vapor pressure but that may be too much info

that makes sense though. I will try it with the a/c on today.

[fastivaca]

Also make sure that you have the air set to fresh and not recirc. I had a "problem" a while ago with my windows not clearing on the inside. I had recently had the heating system out to replace the heater core and had forgotten to reconnect the cable for the fresh/recirc air door so it was stuck on recirc. Reconnected the cable, set it to fresh, "problem" fixed.

[CharlieZ]

Quick fogging could be caused by even a small coolant leak in the Htr-core.

[GenevaDirt]

I would use recirc....if you bring in outside air it can cause the moisture build up too.
When I was delivering pizza and it was cold or rainy mine would fog up.....crack the window a little bit and it would clear right up.