Topic: 1980 4x4 heater mystery? (SOLVED THANKS)

[69800]

 

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

[locked 4x4]

I have a 1980 pickup 2 and my valve is under the hood bolted to the firewall.  It is right smack in the middle upper part.  It shares a bracket with the vacume line for the brake booster.  You cant miss it

[Crawlin4fun]

yep, under the hood is the heater control valve, but what you are seeing may go to one of the Flaps that control where the heat goes and/or how much heat you have. if the end of the cable is laying inside the truck it doesn't hook to the heater control valve unless someone pulled it through the firewall.

check the heater control valve under the hood in the center top of the firewall and it should have a cable attached ( on my 80 the cable is blue ) if not then you will have to push the cable thats laying in the truck through the grommet in the firewall to hook it up

[YotaNate]

Here is a pic from my truck.  It's right on the firewall, all it does is allow hot water to circulate through the heater core or shut off the flow.



Nate

[Rocksurfer]

They are correct the control valve is on the firewall inside the engine, FYI if you leave the vent on it will draw cold air. You must have it in the defrost or heat position.

[69800 [OP]]

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

ps. I think it must by plugged so I thing I will gently use the garden hose and see what I can clear out
m

[Rocksurfer]

If everything is the same in the pictures except for the valve then you should have coolant flowing through the heater core. Make sure that it has not been bypassed and that nothing is flowing in. The issue I mentioned earlier would keep airflow from passing through the heater core if it is in the vent position. If you move the lever to defrost does it then clear the windshield? If it does then it is working and if you move the lever to the heater position then you should get heat at your feet.

[Rocksurfer]

Also if you have it in the vent position cold air will come through the center vents pictured.

[locked 4x4]

to check if its clogged just warm the truck up and see if the lines are hot.  Mine get hot as hell when the valve is open

[69800 [OP]]

I am speaking of heat or defrost positions only. I do get just a little heat and both heater hoses are hot. So I am pretty well convince now that its a partial block. I will know today when I blow it out.
thanks all
mark

[69800 [OP]]

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

[wakkjobb]

Just a thought; my girl's 79 didn't have that control valve so we just ran heater hose straight to the tubes for the heater core. Full heat all the time; made a by-pass hose for summer though.

[69800 [OP]]

thats what I will do
thanks

[JoeWelder]

thanks for this post, i fixd my heater! my heater never got that warm so i just read this post and lookd at my bracket / cable and the piece the cable connects onto, was bent, not letting the valve open all the way....thanks guys!