2003 mitsubishi galant, heater blowing cold air. Have had the thermostat replaced 2 mos ago. what could be the problem

that happened to me the heater core went out ive read alot of different things about 03 galants most of them have the same problem it started with a grinding noise turning the temp contol, its actually the heater control motor value it causes the heater core to go out

There is probably some kind of damper that opens and closes under the dash that allows the air from the blower to be blow across the heater core under the dash. Sometimes these are controlled electronically or by vacuum tubes. Look underneath the dash and look for small vacuum hoses that might be dangling loose or possible little wire cables that might have come off the sides.
Possibly check Haynes Manuals (www.haynes.com) to learn how to change a Heater Control Valve.

Did you replace the thermostat? If it is stuck open the coolant may not get hot enough to be effective.

you need a new heater core

check thermostat,if ok replace heater core.











TIM....

plugged heater core need to flush it out

the clamp is definitely not tight... tighten it first and see if there is a change in heat also refill what you lost in antifreeze also see it the hose itself is not leaking if so replace both to be sure and possible flush the heater core while your at that point .

try to back flush the heater core. and if that dont work check the blend door it see if it is working.

if your blower fan is working and it blows would mean you will need to have your thermostat replaced.

This may be a solution:
I had a similar problem at the beginning of this winter.
My heater was blowing cold air.

My solution:
Heater Temperature control cable, about $10 from dealer
Install, about $70, at my local Firestone