2003 problems

Hi guys, first time on here. I just bought a 2003 with the 4.3 and crew cab. Is the blend door hooked to vaccum at all ? I ask because when I go up a hill cold air blows out of my dash vents and going down or level heat blows out the defrost vents. All this with the heater and fan shut off. I know you lose vaccum going up hill and this is why I am asking. Thanks

Hi guys, first time on here. I just bought a 2003 with the 4.3 and crew cab. Is the blend door hooked to vaccum at all ? I ask because when I go up a hill cold air blows out of my dash vents and going down or level heat blows out the defrost vents. All this with the heater and fan shut off. I know you lose vaccum going up hill and this is why I am asking. Thanks

Make sure it is getting good full engine vacuumed to it.

Unless it is leaking vacuum bad it should hold vacuum in vacuum ball
/ tank and check valve going up hill under load.

Hook a hand held vacuum pump to blend door actuator and see if it is leaking.

Post back what you find.

Thanks, So you are saying that there is a hose going to the actuator?

Thanks, So you are saying that there is a hose going to the actuator?

Make and model and auto heater/ac or regular?
If acting up on a pull your are losing vacuum some place.
Have you checked the vacuum to it?

Truck is a 2003 s-10 crew cab with 4.3 I think it is just the standard heating control. Hav'nt checked anything other than I did check the heater sitting still and it seems to change from dash vents to defrost ok but when on the floor it does'nt seem to put out much.

Truck is a 2003 s-10 crew cab with 4.3 I think it is just the standard heating control. Hav'nt checked anything other than I did check the heater sitting still and it seems to change from dash vents to defrost ok but when on the floor it does'nt seem to put out much.

Check and confirm good engine vacuum to heater and heater controls.

Let us know how it goes.

I will this weekend, and thank you for all your help, Keith