Wheezing/Moaning and Spotty Heating Ford F150

I have a 2000 F150 that has had an intermittent wheezing/moaning sound while driving, for over a year now. I thought it was a brake or belt wear issue but it doesn’t always happen, and sometimes while driving highway speed, sometimes in town, both summer and winter. Finally, I have heard it a couple times after parking in my garage, at standstill just before turning off the engine. A month ago, the heater started to intermittently stop putting out heat. The fan still works, and switching from floor to panel, etc. sometimes fixes the problem, and sometimes not. The heat sometimes fades while driving w/o changing any settings. After sitting, it usually comes back. I am wondering if these 2 are related and the moaning is some sort of air-flow related thing behind the dash that is now showing up as the cause for the heat shutting off. Anyone had anything similar? The truck as about 134K miles.

Thanks for any help, and your “Lousy Radio Show” is the best!

The ventilation system in your truck uses vacuum motors to operate the different doors in the system. In this system is a vaccum reservior with a check valve located under the hood. If there’s a leak at this vacuum reservior it can cause the noise you describe along with the erratic operation of the ventilation system.


That makes sense, and sounds a lot less expensive than tearing the dash apart. I’ll have my mechanic check it out. Thanks for the response!