heater question

[xj2864]

hey guys i know this is an xj forum but i have a question about a 2001 tj heater. my girlfriends tj heater blows out cold air when it is sitting still but works fine when you start driving.. any idea what is wrong. thanks

 

[Mercenary]

Check your coolant level. Some vehicles have a by-pass that sends all coolant to the motor instead of the heater core. If your system is low, then it could be that all of the coolant is being directed away from your heater for engine cooling.