Hot Air Coming From Dashboard Vents and Floors Vents

#1

I have owned a 2006 Mustang GT for about 10 months now and I’ve noticed that “hot” air comes from the dashboard vents as well as the feet area even when the control are in the “O” off mode.



When I turn on the “real” hot air, the this unique hot air stops.



The dealer looked at it 3 times and deemed this “normal”, but I’ve never had this situation with any car before and the hot air is just too much for it to be normal. Dealer said this is normal for all current models and the only way to solve the problem is to tun on the A/C.



Is this normal?

#2

Does your car have a valve that controls the flow of hot coolant to the heater core? The valve would be controlled by the dashboard’s cold-hot slider or rotatable knob. I am guessing not.

Some cars have the hot coolant flowing through the heater core all the time. In that case, there are doors that flap open or closed or in between to conduct air that has passed through the heater core into the passenger compartment. If you are sensitive to radiant heat, you will be aware of the hot heater core even if these doors are closed. If they are even slightly open, or not well sealed, warm air will pass into the passenger compartment, even if you have your heater control set on Cold and the fan on Off. Many cars pressurize the passenger compartment by having the fan blow even when set on Off. This helps prevent exhaust gases from entering the passenger compartment… but may mean that air that has passed through the warm heater core is being sent into the passenger compartment.

Your dealer may be right: only using the AC will overcome the ingress of heat.

My 1984 Chevy Cavalier let hot coolant into the heater core all the time. I experienced something like what you are now. When its AC failed I spent big bucks to fix it. When I replaced that car in 1999 after 207,000 miles I looked for a car that had a valve to keep hot coolant out of the heater core. That is one reason why I bought a Honda Civic in 1999. I still have it. But I am still impressed with that 1984 Chevy Cavalier tht went 207,000 miles!

#3

You could be right.

However, the hot air doesn’t just come from the passenger side, it comes from the driver’s side as well. And from the dashboard vents. When I turn on the defrost, I can hear the vent doors locking, and soon the hot air stops. This is bad especially when the weather is hot outside. The hot air feels like it’s the engine’s hot air passing through in the off mode.

#4

Relying on a electric fan to keep exaust gases out of the passenger compartment sounds very shortsighted.

#5

I’ve heard of some GM cars doing this (fan always on), but I’m not aware of any Ford cars that do.

#6

The heater core is always hot, so any air flowing through, or near, the core will be heated. There is ALWAYS some air flowing through the HVAC system, even when it’s “off.”

Perhaps the blend door, which regulates interior air temperature, allows some incoming air to pass through the heater core. There isn’t really any other explanation.

What happens when you have air coming out the dash vents, fan on low, but the temperature control is all the way to cold (AC off)? Is the air hot?