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Jim Grant's Tech Tips
88
Lincoln Mark VII, LSC Sedan, No Heat
Q: I have recently moved to NH from Miami,
Florida. As soon as I got here I realized I had no heat in my ‘88 Lincoln
Mark VII, LSC. I took it to a local dealer and their diagnosis was the
water pump needed to be replaced and it needed to be flushed. My lady
friends son is a pretty handy fellow when it comes to repairs, so I asked
him about this and he said this didn’t sound quite logical. (Water pumps
are to cool engines, not heat them.) We have flushed the engine and put
in new coolant, replaced the thermostat, and checked the flow of water
into the heater core and out and this appears to be normal. We also replaced
the coolant temperature sending unit. Still no heat to speak of. Further,
I have the control set for 90 and we get just slight warm air from vents
(you have to place your hand on the vent to feel the slight heat; if this
temperature is lowered to 85 degrees, the next setting, the vents blow
real cold air not any heat! Any suggestions to solve the problem? Sure
would feel nice to ride in a warm car in this NH winter. Thanks for your
help.
A: First,
water pumps do not cool the engine. The water pump merely allows for the
circulation of coolant. It is the coolant that allows for the transfer
of heat whether to the heater or the radiator. If a water pump does not
provide good coolant circulation a heater will work poorly and the engine
can operate too hot at the same time. It sounds as if you’ve covered the
basis with the cooling system service you described. If all is correct
then the problem is likely to be with the heater control system of the
vehicle. The automatic climate control system in your vehicle does have
built in diagnostic abilities. To enter diagnostics you have to push the
Off/Auto and Defrost buttons at the same time. When the climate control
computer enters into self diagnostics the display at the heater control
panel will display numbers, (example 01 which would indicate that a blend
door is out of position. There are 15 different codes that the computer
can display as reference to the diagnostic procedure needed to effect
a repair on the heating system. To exit the self diagnostic mode you have
to push the cool button. If you don’t, the heater will stay in the diagnostic
mode and will not function at all. You may want to have a technician that
is familiar with your vehicle’s climate control system perform the diagnostic
and repairs.
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