2003 4x4, F150 with electronic climate control.

I've got no air (at all) coming out of the floor (heater) ducting. Fan works fine in defrost, so it's not the fan.

There is hot water in the heater core, so it's not the heater core. You can feel the heat if you put your hand near it but no air flow thru the floor ducts. No air whatsoever out of vents either.

The defrost setting works (has air coming out).

There is full engine vacuum (16.5") to the check valve in the engine compartment near the firewall by the battery but that black line looks like it goes under the battery and not into the firewall. Maybe I'm looking at the wrong line.

I pulled the vacuum connector off the vacuum servo that is on the driver's side of the tranny hump. It looks like it should control the heater ducts on the floor. There are 2 vacuum lines in this connector (yellow and blue). I put a vacuum line on these 2 lines and when HEAT is selected, one line has only 1" of vacuum (engine vacuum is 16.5") and the other line had 0" of vacuum. So it appears no vacuum is going to this servo.

Is this a vacuum leak? A controller problem or something else? I don't have a repair manual for this truck so I don't know what to do next. I can't even find the vacuum line going into the firewall.

If there is an online manual for the HVAC that is available I would appreciate a link.

Is this a common problem on this truck?

Any help is appreciated.

Thanks, DEWFPO

 

>>near the firewall by the battery but that black line looks like it goes under the >>battery and not into the firewall. Maybe I'm looking at the wrong line.

On my 2003. that line that you're looking at has a "t" in it behind the battery and the black line from the "t" goes thru the dash. If I pull that line off, all I can get is defroster air flow. Tracka96

 

Thanks for the info. I'm going to pull the battery this weekend and hope it's a simple vacuum leak.

DEWFPO