Blend door changes with engine speed
#1
Blend door changes with engine speed
2001 quad cab sport 4x4 5.9. When i get on the gas or even just climb a hill on cruise the blend door moves from the vents to the defrost then back again when the engine is no longer under a load. Thinking a vacuum problem. Any ideas?
thanks for the help
thanks for the help
#3
#4
I had the exact same problem years ago.
Good luck!
#5
Use a vacuum pump and check lines to see if they hold vacuum. If all looks good verify the two check valves on the passenger side of the motor are functioning properly. Take them off and blow through both sides, they should flow one direction only. I just fixed the same issue this morning on mine and used a Dorman 47149 valve which cost $7 at the local parts store. The diaphragm was screwed up on the one near the intake manifold for me and flowed both ways. With this new one I had to make up a reducer on one side to adapt to the stock T-fitting. Took all of 5 minutes and some spare hose / a reducer fitting I had in the parts bins