Water Valve Heater
 

Not sure if I have my heater hoses run correctly and if I have the water valve on the proper hose. I have A/C it is a "Four Season System" 1972 1/2 ton factory air.I have one hose from intake manifold to heater core and one from the top of radiator to core. The water valve is on hose from radiator. I think I have hot water in heater core all the time. Anybody know the correct configuration for this??? Auto trans 350 engine Thanks for the help. Gets real hot in the cab during these summer days!!!

Re: Water Valve Heater
 

Do you have the vacuum hose connected to the heater valve? Vacuum has to be applied to the valve to close it and prevent coolant from circulating thru it. Your rad. hoses sound like they are routed properly.

Re: Water Valve Heater
 

I can check my truck's hose routing in the morning if there's still any question.

Re: Water Valve Heater
 

Yes I am getting vacuum to valve. I was concerned I had hose routed wrong.

Re: Water Valve Heater
 

My '72 K20 (350/TH350) has factory A/C and is plumbed differently than yours. The valve is on the 5/8" hose from the intake manifold to the lower port on the heater core. The upper heater core port has a 3/4" hose going to the radiator.

The odd thing is that with different size hoses, the valve will only fit on the 5/8" hose, yet yours is on the hose from the radiator.... which on my truck is 3/4".

Re: Water Valve Heater
 

Sorry I was wrong I do have mine plumbed like yours.
From top of core to top of radiator... From bottom of core 3/4 to valve out of valve to 5/8 connecting to intake. What is the direction of water circulation???
The problem I am having is the vacuum logic is not matching what the heater control is set at. I get hot water through my core when I should not have flow. Could my vacuum VALVE ON THE CONTRILLER IN MY TRUCK BE PLUMBED BACWARDS?? Sorry for the caps hit the wrong key...

Re: Water Valve Heater
 

Not positive but I think there is two different valves for these trucks One is open under vac and one is closed, Make sure yours is closed when the AC is on. Water should go from manifold to heater and back to radiator

Re: Water Valve Heater
 

Looking at the valve, the pipe pointing straight away from it goes to the heater core. The curved pipe connects to the intake manifold.

Water flows from the intake manifold to the valve -- from the valve to the lower port of the heater core -- from the upper port of the heater core to the radiator.

Re: Water Valve Heater
 

Thank You Stocker for that very clear explanation. That is the way I have mine setup. Next step is to check vacuum control from controller in truck.

Re: Water Valve Heater
 

This is also correct. Check and see which one you have, the 71/72 valve should close with vacuum applied.

Re: Water Valve Heater
 

I had a similar problem on my 72. I bought a new valve and installed it. Still hot in the cab. Finally found a vac hose loose under the dash. Reconnected it and things got a lot cooler. AC was running the whole time, it was just mixing hot air with it. Maybe this will help.

Re: Water Valve Heater
 

That could be it. I will check to see if I have the correct valve. I bought it from LMC but they could have mixed them up!!