Heater issues

[1967stella]

Ok so i have probably only moved the switches once in about 2 years since i bought the truck(67swb) and i tried to turn them on thw other day and no heat at all even when the truck is fully warmed up, the fan is blowing deciently hard. I havent gone in and taken apart the whole thing to get all the leaves and stuff out of the fan yet. What does this sound like .. And also does anybody have pictures of where the cables go on the back of the switch.. I have just heat no ac
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[1967stella]

I highly doubt that the cables are hooked up correctly
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[z10kl]

I bought a Camaro once that had plugs RTVed into the heater hoses. The heater core leaked and instead of replacing it they made it look like everything was ok.

[Hubscrub]

are your heater hoses hot? when you cleaned it out did you look in where the heater core is? they can be packed full of junk from rodents, also check the cables and the levers in the box that they are opening the doors correctly to allow heat in

[1967stella]

I havent had the time to open it up to clean it up. I honestly wouldnt know hat to look for haha ive taken just about every thing else in these trucks apart ive been puttin this off since i bought her.. My wife finally complained about it not blowing heat..
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[1967stella]

Can anybody helpwith the proper cable hook up locations from the back of the controller to the actual heater
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['68 C-20]

You can actually lay on the floor and move the gates by hand to see what is hooked to what. Floor to defrost is real easy. It is in front. Temp control is a little tougher 'cause it is just out of reach in back of the plastic.
I think I have some diagrams in my service manual, I will see if I can find the page and scan it for you.

As has been said, first thing to do is to see both hoses into the heater box are hot. Then you know you have circulation.
Then you will need to get into the heater box and clean thr debris out of it.
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['68 C-20]

Here are some scans from the manual. First one shows the heater assembly on the Engine side, Don't bother to take any of it apart until you know that you have circulation! If you do not have circulation, you can pull the heater lines and put a garden hose to the heater and flush it in both directions. That will help to wash out the sludge, if you have sludge you ought to buy a bottle of radiator flush and flush the system. If your heater core is plugged, then you probably have compromised flow in the engine cooling system as well.

The heater box is pretty easy to get off from the engine side and will allow you the best access to clean it out. If you have compressed air, you can reach through the blower hole from the firewall side and blow air through the box, into the cab, while moving the gates. Prepare for the dust storm in the cab!

It is easy to lay on the floor and see if your control cables are working. Attached is where the control cables run to. If they are stiff you can lubricate them, (I use a little tranny fluid myself) it will follow the inner cable down the line. I put some on the outside of the cable as well, particularly at bends, I am pretty sure it can migrate through the winding of the outer casing and lubricate the inside.

[1967stella]

Thank you soo much!!! I was messing with it today befre i saw this and the previous owner did have the cables switxhed..i can get a deciently hot air going through the lines and i checked the line coming off the water pump and it feels like there is almost no pressure in it but it is hot.. Im ordering the gasket set and new hoses from LMC friday then i will take it all apart.. Also quick question do you knkw where i can getthw little lock washers that are on the end of the controll piece. The ones that make sure te cables dont slide off, i cant find em that small any where
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['68 C-20]

If you squeeze the hose going into the out of the heater you will not feel any pressure. The water pump circulates the water, it does not put out any pressure that you will be able to feel. Just make sure they are both hot.

Regarding the retainers, you should be able to buy them at NAPA or a decent "Old Chain" auto parts store. They sort of get out of whack when you take them off, but I have tapped them flat with a hammer and re-installed them. Take one with you when you go into the store, find the oldest counter man there and show it to him. Don't bother with the Autozones or Advanced, or Pep Boys, IMO they do not have the experience to understand what you need.

[chopnchaneled]

Subcribed,,,,,,,, I have ths same issue.

I flushed the heater core when replacing the heater hoses and water flowed real good, both hoses are getting hot but no real heat on defrost or heat. the doors switch which way the air blows, Oh and mines a 68 if that make any difference?

['68 C-20]

Did you pull the heater box from the firewall to look inside? There could be a nest around the heater core or in the fan housing, or in the box right in front of the fan housing. Does the fan push air out of the defrost ducts and the heat ducts when you select heat or defrost? The air is just cold or are you not getting airflow but it is hot?