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I might have missed this, if was discussed. Does the cable running from the dash operate a door in the box under the hood? Directing air from the fan either thru the heater core OR thru the cooling unit?
...cable running from the dash operate a door in the box under the hood?
Directing air from the fan either thru the heater core OR thru the cooling unit?
Yes. :)
and
Yes. :)
But most of the time (while the hot water is going through the hear core and
the heater is "on") the lever will be part way directing part of the air over the
heater core and part will either be vented air from outside or recirculated air
from inside depending on whether the flapper door is closed or open (that
you can see there) by the passenger's foot space.
Got to be the heater flow control valve found on the 5/8" hoses running to and from the coil. See if the vacuum line running to it is ok and connected on both ends (one end to the valve, the other to a good vacuum port usually on the vacuum "tree" behind the intake). If you have a vacuum leak in this hose, this may be your problem. The valve may also be bad and leaking vacuum pressure.