My heater isn't working at all. I always thought it was tied into my a/c and without the compressor the heater wouldn't work. Is the heater tied into the a/c system? I'm not familiar with this at all and my wiring diagram is driving me mad. I looked up some old posts and someone mentioned having the cats removed might have something to do with it? I've looked and it looks like I've got power going to the heater, but I'm not sure exactly how it works and my Haynes isn't offering much help.
I checked all my hoses and they are solid too.

 

The AC compressor has no effect on your heat. Check the heater control valve, it is located in the engine compartment on one of the heater hoses coming off of the water pump. The heater control valve is operated by vacuum. The hard plastic vacuum lines on my '79 Vette were blocked solid and would not actuate the heater control valve. Also the older heater control valves were made from metal and prone to corroding on the inside making them inoperational. The new replacement heater control valves are made from plastic and do not corrode, they only cost about $15.00. Make sure that you are getting vacuum to the control valve and make sure that the control valve is not stuck from crud in it. Another possibility is that a previous owner may have bypassed the heater core completely by removing the heater hoses from the heater core and simply connecting the hoses to each other.
I hope that helps!

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DeeVee hit the nail on the head. No heat is most very likely the heater control valve and it is operated by vacuum.
If the heater core is by-passed, you'll see the two metal short tubes sticking out of the heater core in the engine compartment. The heater system is very simple and finding the control valve only takes following the heater hoses.
If it's an emergency, just get a new piece of hose and leave the control valve out making the heat "on" all the time until you can get and install a new valve.

DeeVee, "Hellafied Quick Reply Time." You hooked Rick right up. And with the cold front that came out of the north west and this next one coming, that heater will be needed even in the southern states. In the northern states, that defroster will be a necessity-thank God I don't have to deal with those New York winters anymore.

 

Thanks Texas Jim, mighty kind of 'ya.


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Thanks for the advice you guys. =) The heater wasn't bypassed. I think the control valve is bad. I'm going to check it tommorow in the daylight.

 

All the advice is right on and heres one more thing to check, when I turn the thumbwheel ( next to the shifter ) it turns very easy but when it stops I have no heat, I have to use just a little more force to make the heat work, that supplys vacuum to the control valve which opens the control valve. PG.

 

When you say you have no heat do you mean its blowing out cold air or do you mean the blower motor doesn't work?

 

Nothing blows out of the vents.

 

Rick - can you clarify some things for us? Do you get any hot or cold air coming out of any of your vents? Can you change the air flow -let's say, from the floor to the dash vents or to the defroster? Does your blower fan run? Can you change the temperature from hot to cold or vice- versa?

Thanks!

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Nothing comes out of the vents at all. The A/C was disabled by the previous owner during the engine rebuild. He took the compressor brackets off and left them in another state. The heater has all components though. At least as far as I know.