heater quit working..

so my heater quit working out of no where. chekced the fuse and it is fine. replaced it just in case and still wont put out harm air...it is blowing good but just not hot air...what could be the prob guys..

oh this is on a 90 crx si

heater core... check for plugging in core/lines, check thermostat, and check radiator cap for pressure leakage. should be around 13psi before it opens.

and i know this sounds stupid, but make sure the dial indicator is on hot instead of cold, and the wire in the back actually moves the door in the ductwork... sometimes they break and get stuck in the cold position.

Your heater has nothing to do with a fuse, that is unless you are saying that the fan wont blow anymore. The heater gets its heat from the engine via lines running into the car to the heater core. Follow the advice above. Ive seen plugged lines before, it does happen. But usually not if the heat was working just recently. A month or more of non-use could let crud build up in the line. Did you put the dial to cold after the last time it worked? The linkages could have disconnected and be stuck on cold.