Jim Grant's Tech Tips
Dodge 4wd, Luke Warm Heat
opens on my 96 Dodge 4WD the heater blows only luke warm air.
I took it to the Dodge Dealer; they put in a new water pump and
thermostat. I still have the same problem. Do you have any ideas?
If the coolant
is at the correct level and the thermostat is operating at the correct
temperature then I would suggest moving your inspection toward the
heater. Heater cores can become blocked or restricted. With the
engine fully warmed up and the heater blower motor off, compare
the temperature of the upper radiator hose with the hose to and
from the heater core. The temperature, in general, should be about
the same on all three hoses. If you find that one of the heater
hoses is cooler, it is possible that the heater core is restricted.
To confirm, have a technician check the flow rate through the heater
core. If restricted I would suggest a replacement with a full cooling
system flush. Depending on which model Dodge you have, beware of
an ALLDATA Information System TSB addressing a problem with the
cable from the heater control that operates the blend door for the
heater. The problem? The cable slips on the arm of the blend door.
When this happens the temperature from the heater cant be
controlled correctly. The fix is easy, requiring only an adjustment
on the blend doors arm to prevent the problem.