98 blazer ac/heater Problems with vents

[gemcin]

I have two Problems with my heater and have ran out of things to replace. first problem is when i switch to floor vent it goes to defrost vents this happens on both settings that uses the floor vent but everything else works like norm. just floor vent wont work. I replaced the vac control that moves the arm on box and replaced ac/heater control panel. next problem is that the high fan speed dont work either changed the relay on firewall and the piece that sets on top of the box under the hood with the spring looking loops dont know what the part is called. works on all other speeds. THIS IS ON A 98 BLAZER 4x4 reg controls

[old_master]

The vacuum motor that you replaced, was that on the driver side just above transmission tunnel? If so, that motor has two vacuum lines connected to it. With the engine at idle, move the mode switch from heat to defrost and make sure vacuum switches from one line to the other at the motor. Also, make sure the arm moves freely, they have a habit of binding in the heater box.

Heater: Turn ignition switch to the RUN position, HVAC mode switch to HEAT, and blower to HIGH speed. Check for battery voltage on both orange wires at the high blower relay. The larger wire should have battery voltage at all times, the smaller one only when the fan switch is in the HIGH speed position. Check for ground at the black wire.

[chcknugget]

It sounds like the spring on your blending flap is not correct. Have you checked for problems with your in-dash colorful vacuum lines? I just fixed this problem this weekend by switching out the vacuum actuator, vacuum lines and blending door flap.

[jwalker1970]

Same problem with a 1998 Blazer.

Vacuum actuator above trans tunnel moves white plastic piece. Vacuum changes from red line to blue line when switch is moved, no change in air direction.

Is there an internal problem with the flap?? It turns with the vacuum pod unhooked, but don't change air direction.