Guys, i have a problem with my heat in my car, when i turn it on, it works great, but when my fan is off and the heat is off i still have warm/hot air coming out of my vents at all times, i can even feel it coming out of my shifter plate, its not just slowly coming out, its a godd pace all the time, I dont know what it is, but all the time warm air is coming out, even when i turn it on and on to vent? I just replaced the heater control valve, i dont know if i have a vacum leak or what, please help!!

what should i try?
thanks
aj

 

hey i was wondering if you ever found out what the problem was. i have the same problem now. thanks

 

That thread is 10 yrs.old.

 

No matter what u do you will still have air pushing thru the vents while the car is moving.
This is a ancestor to GMs Flow thru Ventilation from the 60s.
My 84 Z-28, 2011 Caddy DTS, 07 Chevy truck, even my 72 Lemans do this...........

Funny tho my dads 07 Dodge Dakota has NO airflow thru any vent if the fan is turned
off.

I guess its a GM thing.....................

 

Ram air coming into the cowl flows down into the heater box. Having temp control set to HOT allows air to be heated, even after system is shut off UNLESS heater core is cooled off BEFORE system is shut off. Heated air blows through system. Mystery solved.

Problem is that the heat control valve needs to close off the coolant flow to the heater core. You have to leave the control head in a vent position (as in NOT off) and move the temp control lever to COLD for about a minute to cool off the heater core before turning the system off. That is, if the vacuum switch attached to the temp control lever in the control head is working. Yes, there is a secondary temp control switch, attached to the temp control lever, that supplies vacuum to the control valve when the temp lever is at full COLD, and only at full COLD. This secondary switch is on the bottom of the control head, and has 2 ports, in and out.

May also be that the temp control cable needs to be adjusted in relation to the position of the temp door.

 

I would not say anything about it being so old, It means they did a search before asking a question, just like you are supposed to do.