Thread: Heater flow direction

Pump flow direction has no bearing on the temperature control, it's always full flow through the heater core. It's done by air flaps in the heater box. A cable or flap has broken, I'd say.

Good grief! That means that even a slight error in flap position will see a little bit of heated air getting mixed into the airflow - just what I want in summer. And (of course) the heater airbox is well-hidden so checking it out will be a pain.

I'm thinking a couple of hose clamps (the sort that pinch the hose shut, not the ones you use near the radiator etc!) would test my theory? And if I'm right and I then "forgot" them until winter...

Anyone come across this issue before, or had experience with long-term use of hose-clamps?

Originally Posted by Canvas Hat

Good grief! That means that even a slight error in flap position will see a little bit of heated air getting mixed into the airflow - just what I want in summer. And (of course) the heater airbox is well-hidden so checking it out will be a pain.

I'm thinking a couple of hose clamps (the sort that pinch the hose shut, not the ones you use near the radiator etc!) would test my theory? And if I'm right and I then "forgot" them until winter...

Anyone come across this issue before, or had experience with long-term use of hose-clamps?

You mustn't permanently block the flow through the heater circuit. This flow is what the engine needs to not develop hot spots while the thermostat is shut. There are a few 4 port heater valves available for Holdens and Fords that can be installed to divert flow from the heater when not needed. Example:

Heater Valve TAP 004 Falcon EA EB ED EL EF AU 8 CYL | eBay

You can close the valve with a cable tie if you don't want to work out a way of operating it by vacuum as in the original application.

Id recommend not blanking or blocking the heater hoses. fit a loop hose if you must bypass the heater.

dissuading words include gasket, expensive, melting and head.