2008 Platinum Armada with cold AC, but NO HOT AIR or Defrost

We have been looking for a well kept Armada for the past several months and finally purchased a 2008 Platinum that has been garage kept. It's really nice, but it was a private sale, and we just discovered the defrost and heat will not blow warm or hot air. The previous owner is saying he wasn't aware of the problem, and I am not even going to try to go after him over it. Not worth the trouble or the drama.
I followed the steps to diagnose the faulty worm gear mechanism in the heater control valve and manually turned the valve 1/4 turn counter clockwise, then another 1/4 turn counter clockwise, and still no heat. All the vents blow air, but only cool air when the AC is off, and Freezing air when the AC is on.
Both hoses on either side of the heater control valve get equally as hot, so it seems that water is flowing when I manually turn the valve.
I am looking for advice and DIY instructions. I cannot afford a dealer service visit. Many thanks in advance.


Active member
The heater control valve is a common problem among the first gen Titan/Armada.

According to this video it says to turn it 180 degrees, maybe you aren't turning it enough.

Another video.