One knob operates a valve to control coolant flow from the engine block to
the heater core. The other redirects air flow from the footwell vents to the
windscreen.
Since the later seems to have some effect, let's consider the former. It is
possible that the cable is disconnected from the valve (or the knob). It is
possible that the valve is stuck in the open position (more commonly the
valve is clogged shut with deposits).
A misadjusted cable from the other knob could cause the air flap to not
fully close in one or the other direction, allowing air flow to both sets of
vents all the time.
So first you need to determine which of these scenarios is true.
Manuals are readily available from Moss Motors and other vendors on the
internet.
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
on 5/30/06 7:48 AM, Steve Johnson at sjohnson@umext.maine.edu wrote:
> It seems that on my 1973 MGB the heater is always on.
> I turn the knobs to less hot to direct it to the windscreen which helps
> some, but it is still on.
> Suggestions?
> Also, would someone know where I could get an owner's manual?
> Thanks
> Steve
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