The other night the function **** for the heater/cooler stopped working, air only comes out of the defrost vents ('99 Mazda B2500), the **** still turns. I took out the center panel and looked behind it. It's all electronic, so I first looked for a fuse that might have blown, but I didn't find a fuse for that specific ****. I then searched the wires to see if one had a short, but I can only inspect what is not difficult to reach. Any advice? I am hoping that I don't have to take in to the rude and over-charging chuckleheads at the dealership.
Haynes manual didn't have any advice to offer.

 

I would get the factory manual on a cd. There are a lot of "pin point tests" in there.

 

I'm thinking vacuum leak here. As I recall, the HVAC system "defaults" to the defroster vents when there is a vacuum leak. Other possiblilty is the notorious blend door problem. Hang on, I'm sure that other people will jump in to help.

 

I'll certainly give that advice a shot. What is the blend door problem?

 

I agree, vacuum leak. The blend door controls the air temperature by covering/uncovering the heater core.

 

Could a hose have been disconnected or came loose when I removed the intake manifold?

 

that is very possible

 

The Haynes manual mentions draining the cooling sysyem when removing the heater core. Could a leak in the cooling system cause the HVAC system to default?