I would start by flushing the heater core.
Remove both heater hoses from the firewall/heater core. Run a garden hose and flow the water both ways through the heater core. Reinstall hoses and refill the antifreeze.
Another option is the blend door in the dash might not be fully swinging to the hot air position. It thats the case you might have to pull the dash to repair that issue.
Friday, November 16th, 2012 AT 3:07 PM