Heater valve replacement help

Mon Nov 24, 2008 8:55 am

Tried to fix my heater this weekend but failed, it would seem the heater control valve has failed closed.

I get the correct 12V at the temp control knob on cold, however that doesn't appear at the plug on the valve. Don't know if thats related to my problems but thought I'd mention it!

I've unplugged the power to the heater valve so it should be open. Flushing through with a hose (bottom to top) I get a trickle out. Unplugging the top hose with the engine running gives nothing, no water flow. Plenty of water coming out the bottom hose though. Bottom hose goes to the back of the head, believe thats the correct way around!

I've tried applying power to the valve but it appears to be dead. Tapping it doesn't help. Doesn't appear to draw any current so assuming a wire has broken internally.

To me that sounds like the heater valve has stuck shut? Don't thiink theres anything else it could be?
I'll have to replace it or at least bodge it such that it remains open for the winter at least. I assume once I remove the valve all the coolant from the heater will flood the footwell?

Mon Nov 24, 2008 9:09 am

Unusual to fail closed, but that's what it seems has happened!
Easy to change, just by removing the inspection panels above and to the right of the glovebox. Easier still if you also remove the two centre consoles.
Take both hoses off under the bonnet and tie them up as high as possible, so no coolant comes out, then flush the heater with clean water. That way, any coolant that leaks onto the carpet will only be water instead of antifreeze.
There's one self tapper that's hard to get a screwdriver onto, and is best replaced by a hex headed screw, and tape the small square nuts into place when you put the fresh valve in.

Tue Nov 25, 2008 8:25 am

Thanks for that, good idea on flushing it out first!
I'll take it off at the weekend and see if I can get it to open. Don't care about it working properly I just want some heat!

Mon Dec 01, 2008 9:10 am

Just to update with a happy ending, got the valve out and it had indeed seized solid in the closed position. Tried clamping it in a vice to close it but it wouldn't budge! Ended up cutting the valve part off the main body and putting it all back together, if it gets too warm in the summer I'll put a new valve in. For now I'm happy not freezing to death...