Heater won't blow hot air

[earlkarboviak]

Anyone that has any information on what else I can do would be greatly appreciatied. I have changed out my thermostat and that worked to get the dash gauge to read in the normal range, but still no hot heat coming out of the vents. Took it to the shop and the mechanic suggested that it was the heater core so he changed it and that didn't do the trick. So he wants to change the heater box that has the flap in it to change the hot and cold air to the cab. That would mean a large sum of money to fix. Is there anything else i can do before i drain my wallet on this?

[cdnsarguy]

Put some info re the truck year, style etc please. Is your heater cable or vacuum operated.

[Aberner101]

Hey, sorry i can't help with the heat problem, but I'm changing my thermostat this weekend, just need some help locating it under the hood. A point in the right direction would be very much appreciated.

[osufireman]

Is the blower blowing air but it's just cold or is it not blowing air at all?? I would check all the connections on the AC/heater adjuster on the dash and make sure everything functions by visualizing it if you feel comfortable tearing into the dash a bit, might save a few $

In regards to the post about the thermostat, follow the hose coming off of the top of the radiator, it comes down right next to the alternator, front of the engine on the passenger side of the truck. It will be inside the housing that the hose is connteced to, just unbolt it...I believe that taking the alternator out of the way may be needed to make it easier.

[cdnsarguy]

Tstat is at the base of the upper coolant manifold.... I will pm you info on R&R

[earlkarboviak]

Originally Posted by cdnsarguy

Put some info re the truck year, style etc please. Is your heater cable or vacuum operated.

The truck is a 1993 Ford F250 7.3 liter diesel and I believe that the hot/cold knob is cable operated. Everything else is vacuum operated, like the defrost switched to the floor, etc. Thanks

[cdnsarguy]

The cable adjustment for the temp is in behind the glove box. Unless there is some debris or a broken door/hinge you should hear the door thump both ways when it stops.
Have you flushed the heater core both ways....... Clamp the hoses then remove them.... using a garden hose flush the core both ways.... watch for crud. Reinstall the hoses and ensure they do not leak, also ensure there is a good sealant applied where the heater tubes go through the firewall. Any leakage will not usually be seen outside as it will migrate into the inside of the firewall and under the floor mat.

[earlkarboviak]

Originally Posted by cdnsarguy

The cable adjustment for the temp is in behind the glove box. Unless there is some debris or a broken door/hinge you should hear the door thump both ways when it stops.
Have you flushed the heater core both ways....... Clamp the hoses then remove them.... using a garden hose flush the core both ways.... watch for crud. Reinstall the hoses and ensure they do not leak, also ensure there is a good sealant applied where the heater tubes go through the firewall. Any leakage will not usually be seen outside as it will migrate into the inside of the firewall and under the floor mat.

Just wanted to post a reply for this problem in case someone else has this problem. There was an ink pen stuck in the flapper door for the hot/cold blend control. It was hiding down in the heater box and so simple a fix, now I have hot nice heat!!