as the title states i realized this the other day when i had my girlfriend in the car and she was wearing sandals and she pointed it out . i stuck my hand down"not that down there" and could feel the heat blowing out..the air is only rushing in while im driving, bringing in all the engine heat into the cabin but only from the floor vent not the dash vents.. i have no ac on the car but plan on installing it this weekand . i figure i should take care of the heat coming in so it doesnt counteract with the cold ac air. how do you guys think this air is getting in i know when i replaced the heater core i didnt put any sealant on the ac cover panel , could this be where the hot air is coming from? any input on what you fellaz might think will be great ..
blowing hot air from floor vents on highway and cruise
- Thread starter gentek10
- Start date
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You need to seal the HVAC cover that is under the hood, water will leak in as well.
You may have a vacuum leak somewhere, a bad heater control valve or a bad vacuum manifold behind the HVAC controls in the dash - I have had all of these problems...
You may have a vacuum leak somewhere, a bad heater control valve or a bad vacuum manifold behind the HVAC controls in the dash - I have had all of these problems...
On my car, I could hear the vacuum leak behind the controls - the circular manifold that attaches to the HVAC selector arm is what was leaking on mine - could not control where the air came our from the dash. Would only come out of defrost or floor.
You will have to check/replace all of the vacuum lines, these cars are old now
-Mark
You will have to check/replace all of the vacuum lines, these cars are old now
-Mark
sounds like i have something to do this weekand . ive been reading so i think im sure what all may need attention.I have heard some air sound coming from behind controls. is there anything i should know about replacing the vacuum block behind the controlz and the vacuum lines, or is it a fairly easy thing to do. i havent checked behind there in a minute but i remember the vacuum lines are colored , is there a reason for this. one more thing , if my heater valve isnt hooked up to the vacuum line could this be a problem? i also dont have a vacuum reserve?
decaturforlife
Member
- Joined
- Feb 21, 2007
- Messages
- 141
Yes if the heater valve vacuum line isnt hooked up. The heater valve vacuum line control the vents. This is a common problem I see on the g-body where I live. People ask why only the floor vent work and the defrost work. Mainly because of the heater valve vacuum line. Some times the vent can be stuck. Is your ac work? If not sometime you will feel more heat than a car with ac
decaturforlife
Member
- Joined
- Feb 21, 2007
- Messages
- 141
You can try them or check out the junk yard for one
- Joined
- May 26, 2001
- Messages
- 9,208
The vacuum controls for AC and the heater really sucks as they had issues when new, and now after 30 or so years they are becoming a real nightmare, and it is even getting worse? 
Seems to me there would be a market just in G-Body field that someone with a little creativity and electronic knowledge and experience could devise a "kit" to eliminate the vacuum crap and convert the controls for electric operation?
Looking under the hood of most late model cars, I cannot even find a vac line?
We did a 1981 Trans Am GN drivetrain install, and to satisfy the customer who wanted AC, we used a Vintage Air kit with NO vacuum controls, just a few control wires went inside.
If someone could modify the under dash unit, it would be worth the time to remove the entire dash to change out the box with the moving doors and a simple control head which would mount in place of the current vac/cable controls.
I have a 1986 T-Type street/strip project car with no AC box/evaporator under the hood, and plan to fit a Vintage Air under dash unit using the stock compressor and custom lines. This should function much better than the stock set up, as we found this true on the Trans Am conversion.
Sorry about "venting" off-topic, but I feel better now!
Seems to me there would be a market just in G-Body field that someone with a little creativity and electronic knowledge and experience could devise a "kit" to eliminate the vacuum crap and convert the controls for electric operation?
Looking under the hood of most late model cars, I cannot even find a vac line?
We did a 1981 Trans Am GN drivetrain install, and to satisfy the customer who wanted AC, we used a Vintage Air kit with NO vacuum controls, just a few control wires went inside.
If someone could modify the under dash unit, it would be worth the time to remove the entire dash to change out the box with the moving doors and a simple control head which would mount in place of the current vac/cable controls.
I have a 1986 T-Type street/strip project car with no AC box/evaporator under the hood, and plan to fit a Vintage Air under dash unit using the stock compressor and custom lines. This should function much better than the stock set up, as we found this true on the Trans Am conversion.
Sorry about "venting" off-topic, but I feel better now!
