1979 Heater Problems
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1979 Heater Problems
On my 1979 F150, I cannot get the heater to work. I replaced the thermostat with a 195 deg new one and the engine temp will come up nicely. I have looked at the hoses and haven't noticed any type of valve or anything. It just appears they run directly from the engine to the heater core.
If anyone can give any advice on how to get heat into the cab, I would certainly appreciate it.
If anyone can give any advice on how to get heat into the cab, I would certainly appreciate it.
Fleet Owner
Joined: Jun 1999
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From: Creedmoor, North Carolina
1979 Heater Problems
ltg, you didn't say wheather your heater motor is working or not. I suspect that your heater core could be clogged, and needs replacing, or the doors aren't opening. Can you hear the vacuum switches working to open the doors to make air flow. Try running the motor (to get vacuum) and switching from off, to defrost, to different heat settings. You should be able to hear the doors moving under the dash.
If the doors are opening, the core is open, and fan motor is running, you should get heat.
Not the time of year to not have heat.
John
66 F100s
In the still cool hours of the night, you can hear chevys rusting away.
If the doors are opening, the core is open, and fan motor is running, you should get heat.
Not the time of year to not have heat.
John
66 F100s
In the still cool hours of the night, you can hear chevys rusting away.
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Joined: Aug 1999
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1979 Heater Problems
I think that the canister on the front passenger side of the truck has something to do supplying vaccuum to the doors to open and close them. Are your vacuum lines running into It ok?
I heard that the cannister holds vaccuum to help operation of the heater doors.
I am not sure whether this is true but check it out.
I heard that the cannister holds vaccuum to help operation of the heater doors.
I am not sure whether this is true but check it out.
Posting Guru
Joined: Aug 1999
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1979 Heater Problems
Thats what I was thinking. Ibelieve mine (79 high-output heater) are cable operated. Some 79ish trucks just dont produce any heat. Find a heater core for a high-output heater, they will drive you clean out of the cab.
Nathan
Nathan
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Junior User
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1979 Heater Problems
Flush your heater core out with a garden hose both directions If a lot of dark water comes out you will know that it was plugged hook it up again and I bet you have heat.
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From: SE PA
1979 Heater Problems
If you have the cable that runs from the control on the dash to the valve in the hose, check to make sure it didn't come off behind the contols. It's just a bend in the cable that keeps it in place and mine had "fallen" out of the hole. The only way to get heat was to move the valve manually to the open position for heat and close to get the A/C cool. Had to open up the dash to get in behind the controls to repair, it won't be coming off again any time soon. Hope it's this simple! Chuck P.
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1979 Heater Problems
You said your truck has a/c,right? a/c equipped trucks have a vaccum operated valve in the heater supply line coming from the water pump.
It is supposed to shut off the water flow to the a/c-heater box while a/c is running. I have had a couple of these fail before. look for a valve in one of your heater hoses with a vaccum line running to it.mostly they get stuck and you will need to replace it. about $10.00 at the local parts house. heat is worth the ten spot. Alan
It is supposed to shut off the water flow to the a/c-heater box while a/c is running. I have had a couple of these fail before. look for a valve in one of your heater hoses with a vaccum line running to it.mostly they get stuck and you will need to replace it. about $10.00 at the local parts house. heat is worth the ten spot. Alan
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1979 Heater Problems
I flushed the heater core out and that seemed to do wonders. As far as the a/c on this truck - its an uncommon setup to me. The heater controls are just as would be on a vehicle with heat only (including the cable actuated doors). The a/c consists of two ***** located on the bottom left of the woodgrain paneling just in front of the passenger seat. On **** is fan control, and the otehr is for min or max cooling. Is it possible that this was an aftermarket system. The truck is a Lariet model by the way.
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