Reader Question: I have a 1998 GMC Jimmy. I am having no problem getting heat into the vehicle in the cold weather. However, I am having a problem directing the airflow to the floor.
I get full air out of defrost and front vents. But when I turn the switch to the floor vent I get just a trickle of heat and air coming out of the floor vents no matter what speed I set it to the majority of the air is forced out through the defrost vents.
What could be the problem and is it difficult to access or repair?
You probably have a “blend door” problem inside the dash. There is a small door that when it receives a signal from the dash control switch will move and divert the air flow in the desired direction you have selected.
I would suspect there is a problem with the blend door motor itself or something is interfering with the operation of the blend door. I have seen pencils and crayons fall down into the dash ductwork from the small defrost vent openings at the top of the dash and lodge in the path of the blend door.
In any case, your mechanic will need to test the dash switch and check the blend door operation cost. It can be costly if the dash needs to be disassembled for access to the problem.
I hope that the problem can be corrected with minimal dash removal and cost to you.