Defrost only

[4x4chase]

I cant find any threads helping me with this. All I am getting is defrost (A/C, Heater and fan) It doest matter it all blows through the defrost vents. Anybody know the easy fix??? It used to be, on older vehicles, just the lever how about the new ones?? Thanks in advance!!

[mjb929rr]

Mine did the same thing a while back. Go to the passenger side of the truck with the hood popped. Look for a grey piece of vacumn hose that runs from the blower motor to a little trumpet looking piece above the passenger side head. Mine had come unplugged. Once plugged in it works like new again.

[DryHeatDude03]

There is a TSB from Ford about this problem...from Dieselman's page as follows...........2005/06 A/C or Ventilation Control Problems:
Trucks built between 9-15-04 to 6-8-05 may blow air out of the defrost vents with the mode selector in other positions. The vacuum pump may also run excessivly. Lower the glove box and inspect the vacuum lines to see if they are wraped around the panel/floor door actuator rod. If the hoses are wraped around the rod, inspect for damage to the hoses. If the hoses cannot be repaired, replace them with part number 5C3Z-19D699-AA for automatic temp control or 5C3Z-19D699-BA for manual climate control.
TSB 05-14-9.

[GregsSD]

The Superdutys are designed to blow air out the defrost vents whenever there is a vacuum problem.

Possible causes are:

Bad vacuum pump
vacuum hose that came loose
broken vacuum hose

If it only does this when you are in 4x4 mode then it is a leak in one of the vacuum hoses going down to the front hubs or a bad hub seal.

[4x4chase]

I bet I know where my leak is!!! I had to roadside repair my intercoller hose on the way back from WY Its tight down there. SOOOO I bet I knocked the vaccum hose off while doing that reapir Ill have to go check thanks guys

[redfishpowerstroke]

Jumping in here, How do you know if your vacuum pump is going bad? I have an '05 superduty that has a vacuum gremlin. Mine works like a charm, most of the time but if it is hot, just the time when you don't want this to happen, it seems to quit. I popped the hood to check the pump, and popped the line off and the pump ran for a second then stopped. Plugged it back in, nothing. Unplugged the wire to check if there was a cut, wire was fine. Plugged it in and it ran and wouldn't stop until I shut the truck down. Started it back up, pump not running but the ac was working fine.

Anybody that can point me in the right direction I would greatly appreciate it. I have the ford dealer service manual coming, hopefully that helps.

[Toddbo34]

Originally Posted by redfishpowerstroke

Jumping in here, How do you know if your vacuum pump is going bad? I have an '05 superduty that has a vacuum gremlin. Mine works like a charm, most of the time but if it is hot, just the time when you don't want this to happen, it seems to quit. I popped the hood to check the pump, and popped the line off and the pump ran for a second then stopped. Plugged it back in, nothing. Unplugged the wire to check if there was a cut, wire was fine. Plugged it in and it ran and wouldn't stop until I shut the truck down. Started it back up, pump not running but the ac was working fine.

Anybody that can point me in the right direction I would greatly appreciate it. I have the ford dealer service manual coming, hopefully that helps.

Mine is doing the same thing and the local diesel mechanic told me that the pump motors are built cheap and the brushes wear out in them. He also told me that it was designed to run until the desired vacuum was reached and then shut off. My motor gets extremely hot telling me that it is bad. Once I bang the heck out of it it'll come back on and just go out again. My local auto parts didn't have a clue what it was so it may be a dealer item only.