Question My 97 Chrysler Cirrus' heater doesn't work when on high. I replaced the
thermostat to no effect. Also, when driven for several miles, the coolant (now
just water) boils. The water temp gauge never shows hot.
Sadly, the coolant has never been changed (97K miles), although it has been
flushed due to two or three boil overs.
After replacing the thermostat, I thought the lack of heat might be due to a
clogged heater core; however, with the water boiling in the engine's water
jacket, I've come to think it may be the water pump.
Do you have any ideas as to what it might be, and whether replacing the
water pump is something I can do on my own. I'm mechanically inclined and
able to do most of my own minor repairs.
AnswerHi Ivan,
I would feel the two hoses that pass from the engine compartment thruough the firewall to the heater, after the car has been running for a while. If the hoses feel quite different in temperature then I would suspect the heater core is clogged. You can remove the hoses and back flush the core with a garden hose.
I would also suggest that you try changing the coolant to be a 50% mixture of anti-freeze and water as that will prevent boiling and improve the flow thru the core for that reason. I would not change the pump yet.
The gauge sensor is also used to determine the fuel mixture, so if the engine is starting and running OK thru the temp range then I suspect the problem is with the actual dash gauge, not the temp sensor.
I am not sure what you mean by "doesn't work on high". Do you mean the blower motor? or that the heater temp turns to cold at the vary hight temp setting?
Roland
