Defroster blows cold air

[cszalai]

Hi all

I have kind of a strange problem.... I have heat from the vents, and the floor but when I put the heat on the defroster I get cold air..... any ideas????

 

[Rons beast]

Hey Cszalai,

I believe the system is working correctly.

The air from the defrost is supposed to be cooler and drier to clean the windshield of fog. Warm moist air would just fog the windshield more.

In AC equiped cars the AC compressor comes on and the air is cooled in the defrost function.

Do you have a problem with operation?

 

[brad6920]

Cszalai,

The defroster is definitely supposed to blow warm air if the temperature dial is set to warm. On some cars, the defroster can be used in conjunction with the a/c which takes moisture out of the air and therefore de-fogs the windshield. Unfortunitely Broncos don't have this feature. I can't help you with this problem however, but I can assure you something is wrong.

Good luck.

 

[miesk5]

yo C,

This is one possibility;

Defroster Poor Performance TSB 98-3-18 for 92-96 Bronco, F 150, F 250 LD & 92-97 F 250 HD/F 350

In defrost position, outside air is discharged through the windshield defroster hose nozzles with a small amount going to the heater outlet floor ducts. All doors are in the no vacuum position. A/C clutch is engaged in ambient temperatures above approximately 50 degrees F and blower circuit is energized.

 

[Seabronc]

What year Bronco is it. It would be a good idea to put your truck's vitals in your signature. That way it would be automatically listed when you post. The function is a little different between years. 86 and prior it is a mechanical function. It could be the door seal that determines how much air passes thru the heater and how much outside air is coming in

Good Luck,

 

[miesk5]

yo C,

as Seabronc advised, post your year, eng. tranny type and any major mods or info relevant to the issue in a post or enter it into your Profile.

I verified the year (94 Bronco) by looking at yiur profile and then looking at some of your other posts here. And that takes time w/my lousy Comcast conn.