heater control knob questions.....

[expressfish]

I just changed out all of my cooling hoses, bled the system w/ the heater on but it wont blow hot air. I ran water thu the heater core in and out connections and blew air thur them too....seems to be fine...not clogged ?? The hoses at the firewall connected to the heater core never get hot, the rest of the hoses do. Is there some type of flapper behind the dash to route cold/ hot air. Would it prevent the water to flow thur the heater core ??? My jeep has a little inline vaccum actuated flapper that allows the hot water to flow thru the core when the heat is selected as an example....kinda lost here

[andyman2487]

You might have the hoses that go into the heater core reversed. I did this once to my car and I never got any heat. I switched them back recently and it's good as new.

[StereoInstaller1]

There is a hot water valve just before the heater core.

Once upon a time, mine was stuck shut, so no heat at all.

I had no money or parts, so I took it out and drilled a hole in it!

[expressfish]

That may explain it. What is the valve controlled by ? Wire, vaccum or such ? I remember at one time after the car sat, I switched the climate control from cold to hot and the knob felt really tight....I forced it anyway to the heat side and heard something pop.

[StereoInstaller1]

The little bitch is controlled by the AC switch, run through a fuse that is (IMO) one of the hardest fuses in the eitire automotive world to get to, much less change....

The fuse is in its own little single fuse holder, basically directly above the gas pedal, but towards the heater core.