a/c , air from front vent getting weak

hi fam , my a/c in my truck works good overall but i noticed today that the air is not coming thru the top vents very strong no matter what setting its on, even when its on full blast, it mostly comes out of the floor vent, does any one know whats going on?, 05 eddie b

I never had this issue with my 08 expy. but my 08 f250 diesel had a 4x4 vacuum leak (the dealer pulled a hose off and didnt put it back on) that caused my front vents not to work and default to the defroster. Basically if i engaged that 4x4 I lost my front vents. in 2x4 they would work again after the vacuum was recovered. Check under the passenger dash and the passenger side in the engine compartment for a vacuum hose that has fallen off or cracked.

I dont think there are exposed hoses under the dash to kick off like my 250 but you never know.

Does your 4x4 engage ok?

Thanks I will check the hoses, it's a 4x2 though

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My bad, the expy is all electronic controls for the HVAC


Does the air flow change at all when you hit the buttons and does your fan speed controls work on all the settings?

If not it may be the blend door or the controller its self not changing the flow.

Normal Operation
Under normal operation, to rotate the mode door actuator clockwise, the electronic manual temperature control (EMTC) module or HVAC module - dual automatic temperature control (DATC) supplies voltage to the FLOOR/DEFROST/PANEL mode door actuator motor through the circuit CH228 (YE/GY), and supplies ground through circuit CH229 (WH/BU). To rotate the mode door actuator counterclockwise, the HVAC module - EMTC or HVAC module - DATC reverses the voltage and ground circuits.

The mode door actuator feedback resistor is supplied a ground from the HVAC module - EMTC or HVAC module - DATC through circuit RH111 (GY/BU) and a 5-volt reference voltage on circuit LH111 (BN/WH). The HVAC module - EMTC or HVAC module - DATC reads the voltage on the mode door actuator feedback circuit VH436 (YE/VT) to determine the mode door actuator position by the position of the actuator feedback resistor wiper arm.

DTC B1003 Mode Door Short/Failure - The module senses no change in actuator feedback voltage when the actuator motor has been energized.

Fan speed works on all settings, havent checked under the hood yet, its storming outside

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checked the air hoses behind the battery going inside the cabin, and the skinny on was snapped, taped it with electrical tape temporarily and seems to do the trick, blowing really hard out the dash vents now, will try to look into a permanent fix now thx sbar09 for the insight

No problem man, when I worked at a really crappy ambulance company, the mechanics wouldnt even look at a truck for HVAC problems. I "fixed" my rigs problem by cutting a small section of oxygen tubing, splicing it in, then taping the living hell out of it. Never had that problem again.