Immediate help needed !!!!

[4wheelcrusin]

I have a 2003 National Islander and I need to know if the dash heater water flows through the heater core from the bottom to the top or from the top to the bottom. I want to install new heat control valves and the new valves have a directional flow indicated on them. I only want to crawl into the upper front of this bus once because it's so tight. Any and all help will be greatly appreciated!

Thanks

[twinboat]

Can't say for sure on yours but most flow from bottom to top. That's so any air, in the core, is pushed up and out..

[LJowdy]

If you don't get an answer and you can see/touch the inlet and outlet hoses. Start the engine in the coach. and place your hands on the hoses. The heater core inlet side will feel much hotter than the outlet side. If you have an infrared laser thermometer point it at the hoses, the inlet will always be hotter than the outlet.

[Mudfrog]

Can you get your hands on the top and bottom hoses by any chance? Or, get a laser thermometer pointed at the hoses? I'd think you could see a difference in temperature between the hoses with the heater running on maximum fan speed. The cooler side would indicate flow back to the radiator.

[Milford 47]

Originally Posted by twinboat

Can't say for sure on yours but most flow from bottom to top. That's so any air, in the core, is pushed up and out..

I agree, that is the only way that is correct

[4wheelcrusin]

Thanks for weighing in guys. I'll try the infrared thermometer trick. I didn't even think of that! dah!!

[Podivin]

You've likely already thought of this, but it will make more of a temp difference if you've got the heater and fan running on high when you check the temps.