Heater zone problem

[Crazy4408pac]

Have a 98 Monte. Am having problems with the heater not switching between the different zones. I'm getting good flow to the defrost. When I switch to a different zone, such as floor, there is no change. There is a little bit of heat flow to the floor but most is still coming through the defrost. If I go to panel/floor I hear a small difference and get a little heat out of the panel vents, but still, most comes out of the defrost vent. Fan works on all speed settings.

 

Any ideas?

 

Thanks

[95 vert]

Vacuum leak to your heater control. Trace your vacuum line on the under hood emissions sticker. That line runs to a storage can below the battery.

You'll find a leak at the storage can or in that plastic line usually.

[Crazy K]

agreed. below the brake master cylinder is a plastic T type junction that can break, or the vacuum ball, which is under the car below the battery.