Heat on passenger side, and very intermittent heat on drivers side.

[ChevyHD25]

2003 Silverado 2500HD gasser. Just got the truck about 6 months ago so I'm not to sure what kind of history, or other work my truck has had done to it previously. Right when I got the truck I started losing my fan settings. I only had 4 and 5. Heat was working better then than it is now.  Anyways, I  replaced the blower motor resistor and that fixed my fan problem. The heat has always been intermittent on the driver side though. And recently it hardly ever works. It's winter now, and here in Illinois its pretty cold. So I would like to get this fixed ASAP. If i mess with the temp. controls it will sometimes switch to heat for me. I can hear the blend door opening and closing. What is my problem. Any questions or clarifications I'd be more than happy to answer! Thanks again.

[Lushyalicious]

Try replacing your blower motor resistor

[txab]

Sounds like actuator issue. Common issue. Usually problem will clear itself temporarily by stopping the engine, removing the key, sometimes even opening /closing the door is required. Driver's side temp actuator is located on passenger side above the trans tunnel. Plenty of Ytube videos showing procedure