So I've been having issues with the heat in my trailblazer. It's not that it's not getting hot, but it doesn't blow nearly as hard as it does on AC. It started out with both sides being weaker than my AC but my right side air was way weaker than the left. Now at max speed on heat, both sides are barely blowing out. But when I turn it to cold, it blows out strongly.

 

Welcome to the Forum!

First question, do you have the manual HVAC controller (with sliders to set the temperature) or the automatic HVAC controller (with ***** and can set the temperature to a specified number)?

If you change the mode switch from heater to vent (so the air comes out of the dash vents), and turn the AC off, how does the flow of air compare to when the AC is turned on (regular AC and not the MAX setting)?

When you have the dash vents selected as the air output, how much air is coming out of the vents for the defroster? How much for the floor vents?

Awaiting your reply.