Heater sometimes blows cold hair

I have a 1998 GTP that for some reason recently is having issues with the heat. Even after I run the car to warm it up, I'll go out to take it to work and the vents will be blowing cold air. Just wondering what would cause this just so I can make the car last me through the winter.

Thanks in advance for any suggestions you might have!

Are the heater hoses getting warm? If not, it could be a stuck t-stat. If they are, I'd say you have a bad temperature control acutator.

well, sometimes the heat does work. sometimes it doesnt. does that tell you anything else as to what it might be?

You're going to have to inspect the heater hoses first. If one is hot and one not, the heater core could be blocked. If both are luke warm, the t-stat is bad. If both are hot, the actuator is not moving to direct the airflow through the heater core.

Mine did this for about a week when I realized one of the plastic elbows cracked and was leaking coolant. I would check your coolant levels.

that would explain why it was running hot when i've been sitting still. thanks guys - for your help.

Do you have the dual air temperature zones for driver and passenger? If so, the temperatures are controlled by a motor powered actuator. One side of mine (Drivers) would only throw heat once, so I dug into it. The drivers side is a bear to get at. You can't see it and work on it at the same time. But I managed to get it out and dissasemble it. Inside, there is little motor that has a gear on it that drives another gear pressed over a splined shaft. That shaft comes out of the unit and moves the temperature damper. The gear on the splined shaft had cracked, causing it to bind with the gear that was attempting to turn it. I actually pulled the gear off of the shaft and rotated it to a point where it was not in range of the drive gear. I put it back together and bingo! Fixed! You do have to reinitialize it by disconnecting the battery so the computer can "learn" where it is, I think. I went to the dealer to inquire about a new assembly. $200 or so! That is why I had to Mcgiver this thing back together. Also, since this one is "faulty", I swapped it with the one on the passenger side (which is identical to the drivers side one, is behind the glove box and is much easier to get at) thinking that I may have to revisit it.