lower cfm's when heater on?

[jimmyv-21]

got the o1 gp gt with 3.8 and dual climate control
when i move the gauges to heat, the blower seems to "kick it down a notch". but when i have them on cool, they blow normal. are the cfm's supposed to be lower when the heat is on? i tried searching this and could not find any posts. thanks ahead of time

[StevePT]

Just a general guess since I've never had a GP heater box apart, but I've had other vehicle's heater boxes apart... There's flappers inside the assembly which actuate depending on your heat setting and the output direction.

I have noticed that when you go from FULL Cold to FULL Heat there is an "audible" difference in the amount of air coming out of the vents.

However, the cold/hot control is independent of the motor so it's not actually slowing down the motor, it's just the direction the air has to take might be a bit more restrictive than the "fresh air" direction.