Heat keeps blowing and blowing...
 

I have a question. The heat in my truck continues to blow when I am driving my truck. The fan is off and the heat arm closes off the door but the faster I drive the more heat comes out of the heater box. I thought it was the blower motor so I unplugged the power wire to it but the heat still blow. Could it be the heat resistor switch? I am pretty frustrated since it is starting to get warm out now. Does anyone have any ideas? Thanks.

Chance

Re: Heat keeps blowing and blowing...
 

I've had trucks do that too, maybe not as bad as yours, pull the heater hoses and cap off the lines for the summer? Kinda Hokey, but I bet it would work...

Re: Heat keeps blowing and blowing...
 

I believe that my truck did this when I first got it and my problem was the heater case was full of s**t and the door couldnt properly shut/seal out the air flow from the heater core. The cable might not be shutting the door properly due to adjustment/debris or it came unhooked from the door altogether?? Did this just "happen" or has it always done it? Hope this helps a little... all I know, someone else will chime in too.

Re: Heat keeps blowing and blowing...
 

There are 3 levers:
One for the defroster (not the problem)
2nd is for the amount of air coming in (middle lever). The other end of this one is inside the cab on the bottom of the heater box. Make sure this is fully closed.
3rd is the heat regulator. With mine, the cable keeps coming off the pin on the door. There's a small rubber boot that covers it up on the inside of the firewall (pass. side). Pull that boot out and make sure the cable is connected and that the door shuts.

As stated by 6772owner, there's probably an entire tree's worth of sh** in there. You may need to take a 12 pack and a Saturday afternoon and pull the heater assembly off the firewall and clean it out. You have to drop the inner fender well down to get to a couple bolts.

Oh and if you do this, plan on the truck being in pieces for a week, because you're going to see a thousand other things that you want to clean up, fix, paint, replace in the process.

HAVE FUN!

Re: Heat keeps blowing and blowing...
 

Instead of capping off the lines, put in a manual ball valve and close it for the summer.

Re: Heat keeps blowing and blowing...
 

...or the cable needs to be adjusted to close this door. I've seen this a few times

Re: Heat keeps blowing and blowing...
 

Great idea

Re: Heat keeps blowing and blowing...
 

x2. I did the ball valve thing on mine and it cools the cab just fine now. The heater and A/C were fighting each other.

Re: Heat keeps blowing and blowing...
 

where did you install the ball valve???...top or bottom hose??

Re: Heat keeps blowing and blowing...
 

It is the bottom one. It is the 5/8 line that hooks into the front of the intake manifold. Originally it had the vacuum valve installed. Hope this helps.

Re: Heat keeps blowing and blowing...
 

I got a ball valve on both. 3/4 standard on upper, 3/4 PEX on lower. Not needed, but really nice when the heater core goes while at Menards. Shut 'er down and drive home.

Re: Heat keeps blowing and blowing...
 

Of subject a little, but didnt only A/C trucks have the vacuum valve to shut off the heater core? My bro's 54' F100 has a cable actuated one that I have thought about adapting to mine, what you guys think?

Re: Heat keeps blowing and blowing...
 

Honestly, these non-A/C heater systems are just not complicated. I would just fix it the way it should be. The ball valves are a good idea, but I wouldn't bother with a cable actuated one.

Re: Heat keeps blowing and blowing...
 

You are correct. The vacuum valve shuts off the heater core when the A/C is on. The heater core sits right next to the A/C evaporator core, and this prevents the heater core from heating up and cancelling out the A/C.

Re: Heat keeps blowing and blowing...
 

Ok thanks guys, I think that my trucks system works just fine now, just didnt know if I could cancel a little more heat transfer bypassing the heater core completely when not needed, I was going to rig the cable for the valve to the hot/cold selector on the control panel so that it worked in unison with the hot/cold selection (ie; slider on hot, coolant flows to core, and slider on cold, no flow) ???