So I have a 2002 Ford F150 Super cab that has the Electronic Heater control. Mine would not switch the air flow lout put location. I have read many articles on here about replacing the orings which I did but this did not seem to help. Found another used unit that was out of a 2002 F150. When I brought it home and tested it, it had some issues also so I opened it up to replace the orings on it but found this to be one of the units that the valves/solonoids are soldered in instead of bolted in. Checked my original unit again and found that when you pushed the different directional buttons for air flow you could not hear the unit clicking or switching. So I took the soldered valve body and installed it in my old unit and now I can hear the unit switching as it should.

OK so here is my issue. When I turn the unit to max air it seems to only want to blow out the defrost. When I have it on automatic and turn the temp to the 60 degree it also only wants to blow out the defrost. Above 60 I can select the air flow to panel. Also when I have it in heat or cool and choose floor I get majority of air out the defrost and only a little out the floor..
I have vacuum going to unit but still having these issues . I guess I could try to dismantle the valve body that is soldered together and try replacing those orings but seems since the only issue is during max air and manual on 60 flow coming out defrost that there might be a different issue. Any help would be appreciated.
Thansk

 

You prolly have a vacuum leak.
Check the vacuum lines to and from the vacuum reservoir located behind the battery, and the line that goes through the firewall.