John---To get the heater valve to return to its "off" position, look at
two areas to see why it's not. Operate the control cable so you can see
it moving at the heater valve. The outer cable sheath should hold fast,
so that the inner cable can still push the valve shut. (Note that
getting two-thirds valv slide movement is OK while favoring a full shut,
rather than full open)
You may have to loosen the clip on the valve body to relocate the outer
cable.
There is no spring-loaded shut feature.
If everything under the hood looks good, and the valve still won't
(push) return to shut position, check that the cable hasn't separated
near the control knob, under the dash. These can sometimes be fixed, or
just replace the cable complete.
The major TR parts suppliers should have these cables in stock.
To be sure the valve "works" correctly, the hoses should be (coolant
temp) hot when the valve slide is opened, even part way. The valve's
internal diaphragm is probably OK, or heat would've been getting thru to
the cockpit, even with a faulty cable connection.
Dick
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