2002 Silverado 1500 4x4 zr1 5.3l Started using the heater the other night, where I once had heat on the temperature setting, I no longer have heat. I must turn the temp **** 50% to just get warmth. 100% seems to work fine. basically I have lost 50% of the operating range. I have a full coolant reservoir. I changed the inside air filter last year, but have not checked this year. I have air flow, that does not seem to be restricted. Any suggestions ?

 

So your issue is it's not pushing heat at 25-50%?

I don't start getting any real heat out of mine until I'm more than 50% 50 and lower is the cold side, so I don't worry about it much, I mean it works, you can feel slight changes, but it doesn't really kick alot of heat til the higher end.

Dunno, I also run a thermometer in one of the vents so I just kinda run off that.

 

Just started this season. Last year as you entered the red zone heat developed. this year cold air until the **** is @ 12 o'clock, about half the dial range.

 

Yeah, if you're not low on coolant, then I'd lean towards the controller.

 

Start with the climate control module , I’m sure you can find a donor truck with one that works properly.