Hey guys, I'm trying to figure out if I have a vacuum problem and I need y'all's opinion. First of all, I have the buzzing/humming coming from behind the dash that seems to plague several people. Then, I was driving down the road the other day with the heater off and I felt hot air coming from the floor vents. What do y'all think?

 

Just bringing this back to the top to see if anyone has any ideas.

 

What was the HVAC settings at? A/C, Panel??? Does it do it at all the settings. What was the temp set at? You may have a blend door problem which is allowing hot air to pass through the floor vents. These trucks have a heater core that is always at engine coolant temp.

Regards

Jean Marc Chartier

 

The hvac was in the "off" position, temp on hot. This was the second time it has done it. I didn't change the position this time, but the first time I did and it stopped when I moved it to "defrost" and then didn't do it again when I moved it back to "off"

 

Also, when I have the heat in the "floor" position, there is a slight amount of heated air coming through the defrost vents. This could be normal, but I feel like I would have noticed it before. What do y'all think?

 

When the engine is hot the heater core is hot. So if the system is set to OFF the hot air has to go somewhere,the floor vents. It is normal for the floor mode to send a small amount of air to the defrost vents.

JMC