On the w/e I had the problem that the demister was stuck on no matter where I positioned the selector switch.

I popped the bonnet and pulled the airline off the top of the airpump. The pump detected the pressure drop and started pumping. I stuck my finger over the air hole and the pump built up the air pressure then stopped.

I then reattached the airline and checked the HVAC. All the setting seemed to be working. It was like I somehow unjammed the demister setting by removing the airline.

One for the memory bank for next time it happens. Anyone else encountered this problem? If so, how was it fixed?

 

Most any vacuum leak will default the HVAC to defrost. It's a safety thing. If you have Electronic select 4 wheel drive you may have a leak in the lines going to the wheels. This is usually the case with this complaint. Can you go into 4 wheel drive?

 

I used 4WD high and low a couple of months ago. I'll check again next time I get the truck out. Does the pump time-out if it runs too long?

 

Where is the airpump in a 2002 F-150?

 

No idea on the F150. You should be able to locate it by the buzzing sound it makes when you turn the ignition on. It buzzes while it builds up pressure, then switches of. Open the bonnet then turn the key on and find the noise!

I re-greased the front hubs with tons of help from Chunder at the F250 GTG the other w/e.

We had the front wheels jacked up and checked the engagement of 4WD once the hubs were done. All worked well.
I was surprised that even with the front wheels in the air, to get the hubs to disengage the wheels had to be turned backward.

Note to self: When coming out of 4WD stop and back up for about 5m to let the hubs disengage.