Question-------------------------
Followup To
Question -
I am only getting air blowing out of defroster vents. When the selector is switched to vents or floor it does not change. Is this controlled by engine vaccuum? What is the most likely cause? 1999 Ford Explorer with 120,000 miles.
Thanks,
John
Answer -
This is controlled by vacuum, if it stays on defrost then you have a leak somewhere. The system defaults to defrost anytime it loses vacuum, for safety reasons so at least the windshield can be defrosted.
Is yours manual control or Automatic?
Dennis,
It is a manual system. I suppose this might make it a little easier to troubleshoot? (I hope) If you were doing this, would you start at the engine and try to locate a vac line heading to the controls and work that way?
AnswerStart at the vacuum source, which should be a red plastic line attached somewhere to the engine. If yours is a SOHC motor, it is on the right side of the intake as I recall. If you have the OHV engine, I think is on the left. There should be some kind of vacuum storage, a can or round ball, that this red line goes to, then changes to black on the other side, this is the one that goes inside to the controls. If nothing is wrong there then you will have to look under the dash and trace 3 or 4 lines to the vacuum motors, one of those may have become disconnected.
On my 2000 Ranger the vacuum line runs to the right side of the engine then to a ball shaped canister near the radiator.
