I have a 2003 trailblazer ext. My issue is that I am replacing the actuators currently and they work just fine now after a reset but the vents don't put out any heat. I've gone below and felt the coolant lines, they seem to be warm and the ac lines seem to be cold. The issue was present before the actuator fix as well. What kind of troubleshooting can I do to fix this issue? My blower works, the temp actuator moves.