[s-cars] Heat/Cooling Malfunction

[Curtis Asplund]

My heater produces little to no heat. For the last few months it has produced random heat.  By this I mean sometimes it was warm, sometimes cold, sometimes hot with no real regard to what temperature it was set at.  Currently, I can put it on defrost and it blows out the proper vents, I can control which vents it blows out of, just not the temperature. It only blows cold with the exception of a tiny amount of heat if it is blowing on my feet but nothing from any other vent.

Last fall, when it was warm, it wouldn't blow ambient air, it was either hot air or it would blow cold with the air conditioner.

Once again, this is all without any respect to what temperature it's set at.

Any thoughts on what I can check? (BTW engine temperature seems constant)

Thanks, 
Curtis
95.5 URS6 Avant