Heater / AC Door Actuator Motor ???

[aphunsdragon]

I just got a 96 blazer 4x4 In October. when I first got it, it blew heat and cold through all vents, dash, floor, defrost... Now it will only blow out of the defrost, no matter what setting it is on. I can hear a little vaccume sound coming from behind the switch, like an air leak...? Does anyone know if this is a problem with the Heater/ Ac door actuator motor, or if it is just the switch? any advise would be wonderful, if it finally 50 degrees here in alaska, but in the mornings, heat would still be nice on my feet!!!

[brcidd]

95% of the time the when they act like yours, the vacuum ball is unplugged that hangs on the hood on the driver's side. See if your black rubber hose is attached to the vacuum reservoir......

[aphunsdragon]

ugh. I got excited for a second there. I just went out and checked, but.... its still plugged in. Thanks for the advise though.

[old_master]

If you're hearing the noise inside the cab, the vacuum line may have come disconnected from the mode switch.

[aphunsdragon]

When I had pulled that part of the dash? off, the lines all seemed to still be connected, but inside the switch there is a metal plate that seems to turn when you turn the switch from floor to dash to defrost, the vac noise seems to be coming from there...

[old_master]

Start the engine and gently pinch each vacuum line with needle nose pliers. When the noise stops, note what color the the vacuum line is and post it here. The vacuum lines are color coded according to what function they serve. This will tell what's leaking.

[aphunsdragon]

grey. It is the only one making any noise. then when I disconnect the thingy (hehe) with the lines, the grey is the only one sucking at all..... there is blue brown orange black or dark blue and the grey.

[old_master]

What position was the mode switch in when you pinched off the grey vacuum line, OFF or HTR? Does it make noise, (leak vacuum), if you move the mode switch to any other position?

[aphunsdragon]

Ok, I can NOT hear the sound when it is on the setting max AC, or floor and def, all other settings I can here the vac leak sound. Also, I drove with the switch box not back in the dash so that I can hear it better and it gets quieter or stops as I accelerate, but as I release the gas pedal it comes right back. Not sure if its all related. I do not get AC either, only cold or warm but only out of the defrost.

[old_master]

The vacuum noise coming and going is normal when accelerating and coasting. Have you checked the vacuum line and check valve going to the vacuum reservoir, and the reservoir itself? The grey vacuum line goes to the water valve, (under the hood near the evaporator housing). Try pinching that line at the water valve and see if air distribution is working properly. Don't worry about the temperature, just that the air is coming out where it should.