I've always been told there is never a stupid question so here we go. I've flushed my heater core and reconnected the hoses. The hoses was in a loop with no heater control valve. I installed a manual valve and put the hoses on. I can not get any heat inside. The temp does get to 195 but the heater hoses don't get hot. Im stumped.

 

You're right, the only stupid question is the one that wasn't asked.
You said you flushed the heater core so it's safe to assume that you were getting flow through it.
If the heater hoses aren't getting hot I would disconnect the heater hoses at the block and check the fittings to see if, over the years, they've become clogged and aren't allowing coolant to flow.
At least that's where I'd start.
Another possibility is that the heater core has become air locked and isn't allowing coolant to flow. I can't remember how to "unlock" it off the top of my head though. I'll see if I can find the instructions.

 

I am getting flow in the lines when I unhook them. And that's what I was thinking it is air locked. I've even tried to unclamp the lines and try to get the air out. Still the same.

 

Here's one post I found on the subject:
The blockage and airlock seem the most likely to me. I'd take the hoses off the core, leave one low and lift the higher and fill er up. When you have just fluid coming out the tube, lift them both, still full, and cap them.

 

Thanks I'll try that. Is there a wright way of flow on the heater core. I have the line from the water pump to the nipple closes to the fender.

 

Here is what I have done for the air lock in the system before, I put in a pair of those flushing tees and loosened the return line cap while it was running until it bled the air out. Just a stupid idea

 

if it happens to be a air lock you can check by disconnecting the heater core and filling it with water and letting the air run out until all you see is water then reconnect the inl. and outl. hoses to the heater core. ( check whether the heat works ) if that does not solve it then u can check the coolant flow in the block to the rad by replacing the thermostat if you haven't already this will also give you an idea of the condition of the coolant internals such as lines and the condition of the block if it is nasty orange and green that is no longer see through and might possibly be hunky then a coolant flush would be a good place to go next, and a coolant flush usually fixes any issues with clogged lines, and if that doesn't work i would point my finger at the water pump and see about replacing it, it may not be pushing coolant through but instead you may be getting an automatic coolant vacuum that is moving fluid but without enough pressure to run the heater core. hope that helps cheers.

 

I changed the antifreeze and ended up with two freeze plugs going out. So I have flushed the block with water both times. Put rubber plugs in until I can change all of them out. I'm going to try the airlock. Thanks for all the help.

 

There is no heater water valve on 1973/79 F100/350's...unless they have factory installed integral A/C (combined with the heater) or the Hi/Lo Comfort Vent System.

D4AZ-18495-A .. Vacuum Controlled Heater Water Valve (Motorcraft YG-136) / Available from Ford.

 

[QUOTE=NumberDummy;14967889]There is no heater water valve on 1973/79 F100/350's...unless they have factory installed integral A/C (combined with the heater) or the Hi/Lo Comfort Vent System.

D4AZ-18495-A .. Vacuum Controlled Heater Water Valve (Motorcraft YG-136) / Available from Ford. It does have factory A/C. I just installed a cheap manual valve. But I will change it to the factory later. Thanks for the part number.

 

You read my mind ND! So thanks for the answer. My 78 Custom (no A/C) does not have one of these values and I wondered if it should.

 

I have come across this thread in my search. I am putting factory AC back into a truck that had the original factory ac removed. I bought a parts truck to do the swap. I am trying to get it all working properly before I remove it and install it in my truck.


I have hot water in both lines going to the heater core, but no heat. I suspect that it may be the door on the housing under the hood. It is stuck in the position shown below. I do not want to open it all up at this point to free it up because if I do, I will need to drain the Freon. So I want to test all I can first.





I will also not that I have no cold air at this point, but I figure I will get the heat taken care of then go to the ac.


Is this door stuck in ac or heat mode?


The ac looks to be intact, it may need a charge. When I got the truck, the ac belt was off.


Thanks