Heating issue with 99 Galant 4cyl

Feel the heater hose going into and out of the heater core on the firewall. If one is hot and the other is cold, then you have found the blockage. Other generic things that can cause this symptom:

Low coolant Trapped air in the cooling system Defective heater inlet valve (not sure if this vehicle has one) Leak in vacuum to the above valve (does not open when control is in heat position) Defective heater blend door or control (again your vehicle may not have one)

If both sides of the heater hoses are cool/cold, then follow the line back to where it gets hot and that will tell you where you have the problem. If both sides are hot, then the problem is with the airflow to/over it. Some vehicles use an air blend door to divert flow around the heater core when AC is in use. Others use the coolant vale in line with the core to stop the flow during AC cycle.

Bob

For a 99, (almost certainly) rubbish. The core is certainly getting some flow or it would not get hot in the first place. What's happening is that the flow is not adequate to reheat the core as the fan cools it down, or the engine is not getting hot enough in the first place. While this MIGHT caused by a collapsed or blocked core, its far more likely to be one of the following:

a) the thermostat is jammed open. This will show up as slow warm up and low running temperature, or a fluctuating temp gauge. The engine should be fully warmed up after about 2 miles or normal driving. Same effect if the coolant level is substantially low. The engine will still run cool, but the heater runs cold due to lack of coolant.

b) one of the heater hoses from the block to the core has collapsed internally. Check and see if any hoses are soft and squishy. Its not uncommmon for a 6 year old car.

c) Unlikely, but the heater valve dash control may not be opening the valve fully.

d) even more unlikely, but the wrong type of coolant (eg GM as I recall) can cause a build up of sludge in the system.

All the above can be checked without swapping out a $1000 item.

Yep, that's the stuff. The manufacturer sure got that one wrong...

Stewart DIBBS

Two points here. First, Todd is correct and the thermostat is almost certainly the fault here. The second and larger problem is with the dealer. The suggestion that your core is the issue is assinine especially without first checking the thermostat. I have caught flak here for stating opinions regarding the service provided by the factory dealers but the truth is a huge percentage of them suck. Look elsewhere for service. Check on the DSM forums for detailed answers to common problems and for help finding quality service in your locale.

Isn't that a lovely word to describe it. Far to many dealers assume the owner is an idiot, even when it should be clear they know as much or more about their car as the dealer staff.

And they don't know the theory of Occam's Razor. ie given several explanations for the same situation, the simplest is generally correct.

The simplest explaination doesn't make the most money. They would have probably thrown in the thermostat and said, "See, we fixed it".