E150 won't blow heat

[azmanxman]

First post here, thanks already!
I have an 97 E150 (4.2 V6) that won't give me any heat. The blower works fine on all speeds but it only comes out cold. I've checked the 'in' and 'out' hoses from the heater core after drving and they are both hot, so I guess no blockage there.
I've also pulled the rotating heater 'knob' and it seems to be OK.

Any ideas on what to check next? Someone told me the knob has some sort of resistance unit to vary current? Could it be an actual damper and how would I check?

Thanks guys.
Craig

[firemanbill13]

i had the same problem. on the passenger side in the heater box is a "blend" door. the door is operated by the temp switch. a small electric motor runs this door. in the end of the door is a molded piece the motor fits in this molde piece wears and breaks. i had to replace the door and all was well