fenagle

New to F-150. Just got an '02 and the heat and air are stuck on vent. Can't get it to defrost or floor. Any way of checking the electronics?

Appreciate any thoughts.

Frank
'02 F-150
Lariat
Super Crew

jstockert

Welcome to the forum Frank. Probably a bad vacuum module. Located under dash in the vicinity of back side of radio. If you lay your head on the floorboard close to gas petal and look up you will see a black cylinder shaped motor with a 10" chrome rod. That I what moves the defrost door. Have someone operate the ac controls and you look in there to see if the arm moves up and down. Also check to make sure the vacuum line is still attached to the black cylinder shaped motor. That is best way I know how to explain it. At one time I found replacements online but can't seem to find now to send pic.

jstockert

This is what I was looking for. It's the panel/defrost panel motor on the left side of pic.

4x4dave

Yep ^ start inspecting any and every vacuum line of the truck. More often than not, one of them is disconnected, leaking etc and it will cause the HVAC system to work weird.

If you have the electronic HVAC system then it could be the little o-rings inside it went bad. That fixed my issues a long time ago.

rcruz3568

The part that he is talking about I've seen people zip tie it in place to hold it at the vent setting because when you have vacuum leaks it defaults to defrost under acceleration.... So someone may have tied it up to keep it from moving.... Seen it on at least 5 different f150s I've worked on