66 Satellite Heater system info and function

[66 Meteor]

I have a 66 Satellite with A/C and heater. At the firewall I have 4 fittings and have seen pics where 2 are used for the inlet and outlet and the other 2 has a U hose. The problem is the previous owner modified (or repaired) the system so now only 2 of the fittings are used for inlet and outlet. The other 2 are still there but hoses have been eliminated. I have additional questions on the inline water control ball valve operation as well as the A/C

Can someone explain to me the heater-A/C system, provide a web source, or is there a reference book with a system diagram etc? The goal is to restore this to the original set-up but I need to understand how it is to properly function.

 

[dpstark2]

The valve on the firewall that is disconnected is the heater control valve. It (stock) meters the flow of coolant into the heater core. The other two lines that are still connected go to your heater core. The valve that is spliced in line is a manual heater control valve. The cable (if done correctly) runs to the temperature control lever in the dash. The reason this is done is that the heater control valves are prone to leaking and for 66-67 impossible to find. I've been looking for one for two years.

So typically, coolant leaves the water pump housing, goes into the valve (which meters it to control heat), exits and loops over to the heater core, goes through the heater core, out the other heater core tube, and back to the water pump housing.

There is one problem with your setup- the stock setup has a temperature probe attached to the heater control valve. If the box gets too cold, it opens the valve to allow some coolant into the box to heat it up and keep it from freezing. If the new manual valve is setup to only _almost_ close, you should be fine. Of course, if your A/C doesn't work, this isn't a concern.

The reason this setup is different than the non-A/C cars is that those cars have a door that meters hot air, not a valve that meters coolant.

Hope that helps. These HVAC boxes are a beast. I've rebuilt mine if you need any more information.