climate control

[gm 4x4]

heat, a.c., vint air; it all comes 0ut my defrost vent no matter where my control knob is set. any help would be appreciated. what should i check before i buy a knew control knob. and find out that is not what the problem is.

[asepgrad98]

sounds like you make have a Vacuum problem. it controls which vint the air comes out of.

[gm 4x4]

it's an 00 sierra 1500; how do i go about gitting to the lines, what do i look for, and how do i go about fixing it. or is it a trip to the dealership? thanks.

[Mike G]

I usually stop by the local library and grab the Chitons or haynes manuals in the reference section. Could be that you have a bad relay that controls the selector. The manuals give scematics (sp?) and all.

 

--Mike

[gm 4x4]

pulled the controls from anouther truck and it still didn't do any thing. a g.m. tech. told me it is most likely the acueaters (flaps) 170$ for bottom, 65$ for top & 5-8 hrs. labor they have to pull seats,dash, and get into the duct work; all electric no vaccume from 99 up. i think i will just be happy it is stuck on defrost lots of ice and snow in the winter and the a.c. still cools just takes a little longer. any input or sugestions?

[redvett]

If you want to fix the system dont even bother with the "Chitons or haynes " manuals get a Helm's factory service manual with the correct info. You should be able to diagnose it from a 1995 and up since they all had motors running the heater& A/C system.

[GnatGoSplat]

Sounds like the mode control motor. It is way up on the HVAC box. You can see it if you look under the driver side dash.

It resembles the one underneath the dash.

 

Mine did the same thing, and I discovered a previous owner had removed the mode control motor entirely. I guess it must have been defective and he pulled it to locate a replacement. Anyway, I bought a new mode control motor (about $35) and installed it where the missing one used to be and that fixed it.

[99-2door]

pulled the controls from anouther truck and it still didn't do any thing. a g.m. tech. told me it is most likely the acueaters (flaps) 170$ for bottom, 65$ for top & 5-8 hrs. labor they have to pull seats,dash, and get into the duct work; all electric no vaccume from 99 up. i think i will just be happy it is stuck on defrost lots of ice and snow in the winter and the a.c. still cools just takes a little longer. any input or sugestions?

Whoever told you they would hqave to take the seats out is a quack!!

Never let them touch your vehicle . 5-8 hours labor......about a 30 minute job.

At worst you have to take off the dash upper shell, whicih takes very little time in the new trucks.