I just got an 80 4x4. Everything is working except there is very litte heat. I traced down the cable from the dash. I runs behind the heater core and is just sitting there with a nice little factory loop in the end ready to be hooked back up to the heat control valve, but I will be darned if I can not find the valve. The steel heater tubes coming down from the firewall inside look to be factory. I have use a mirror to look behind the heat exchanger and cannot find a heat shutoff valve anywhere.
Does any body recall where it is? I was trying not to have to pull the whole heater out of the truck to find it.
Thanks in advance
Mark

 

on my 1983 the heater valve is under the hood on the firewall. Between the brake master and valve cover.

Hope that helps

 

Take a photo of your firewall from inside the engine compartment. In my truck, the valve stopped working, so a previous owner had rigged a valve...didn't connect to the heater control. Basically you open it for the winter when you want heat, close it in the summer when you don't. Someone may have taken the valve out, but it's also possible that it's stuck, or your heater core could be clogged.

Is it hard to move the hot/cold control? Are you saying it moves fine, and you can see the cable sticking out of the firewall in the engine compartment, not attached to anything? That's how mine is.

Yours look anything like this?

 

Wow. Am I in trouble now. The guy I bought the truck from put a new engine in. He stripped everything out of the engine compart ment... painted it and put in a new engine. There is no valve on the firewall anymore.. I can put on in but the blue cable is so short I cannot beleave it went outside the firewall though it may have. With no valve I should have lots of heat in the heater position. Is there another valve inside? I can see the heat/def lever operating all of the various doors and they are all working correctly. Could it be a pluged heat exchanger or is there and interior door I cant see.
Thanks for all of you help
mark

I am now pretty sure its plugged so I think I will gently use the garden hose.
m

 

that engine bay is perfect WOW

 

Thanks. the guy I got it from was really anal about it. Then he lost his job. I felt pretty bad that he had to sell after all of that passion

 

Yeah that's super nice and clean. I can't really see up close to the firewall in that photo, but it looks like coolant would be flowing right in with no restrictions (no valve), so you should have heat. Can't say for sure, but I would say you've either got a sticking thermostat (have you touched the heater core hoses going into the firewall when the engine is warmed up to see if they're hot?), or a clogged heater core, but you'll have to find out for sure. You can definitely try flushing the heater core.

 

Can you see in my photo on the far right side, partially under the hose, the wire with a loop on it sticking out? That's what would control the valve..

 

I see where the blue cable goes now thanks. the guy had hooked up the heater hoses backward. I still dont know why the heat exchanger care which way the water goes but it does. I will try to find a valve I can hook the cable up to later.
thanks again

 

Nice, glad you figured it out.