Car overheating while heater is on

[Seriously]

2003 honda civic lx
153k, miles
it overheats and only while the heater in on? this is my friends car and she is 400 miles away, any advise?

the car does not do it when the a.c is on or cold air only when you try and blow hot air and the air never gets hot... possibly clogged radiator?

[AutechKouki]

Seriously seriously? A civic? Haha

But I'm a nice guy. Possible causes could be low coolant level or bad water pump.

[Seriously]

lol thanks for the reply, its not my car, but i will be visiting soon so i will be doing the timing belt, front main seal, water pump ect. while im there