84 C10 blower won't come on

[Landon730]

I can't get the blower to kick on and it looks like it was replaced not long ago. (Truck was last on road in 2008 lol) But anyways I THINK its the control head because the sliders feel pretty loose. Checked with a multimeter and we have voltage to the relay under the hood. Had to run a direct wire from a/c compressor to battery to charge the system. Blows cold air out the floor vent but whenever I use the sliders on the control head nothing changes.

 

[EWC]

Is the vacuum pump working ?

 

[3500GMC]

The blower motor needs a ground and grounds through the flange/case on the motor itself. The fiberglass AC box doesn't offer any electrical conductivity to the cab of the truck. Maybe that's your problem.. ?

 

[Landon730]

Is the vacuum pump working ?

Doesnt have one

 

[Landon730]

The blower motor needs a ground and grounds through the flange/case on the motor itself. The fiberglass AC box doesn't offer any electrical conductivity to the cab of the truck. Maybe that's your problem.. ?

Ill look at it and get some pictures for you tomorrow I didn't think to look for grounds

 

[EWC]

You need a pump , that is what powers the vents and doors . No pump , no movements .

 

[3500GMC]

Yes^^ The HVAC on these were all vacuum actuated. Could be that the blower motor is doing it's thing but you cannot feel any air from the vents. Can't recall if there's a default position, say defrost only, if the vacuum isn't hooked up.

 

[Will L.]

If you don’t want belt driven vacuum pump, just get an electric one in there.

If you have a mighty vac test tool or house vacuum with a hose, just rig it temporarily to the main line where the pump was and test if it opens the valves.

Man I miss when 2 cables controlled everything. Once every 30 years replace a couple $20 cables and only if from a rusty area. Plenty of factory cables in use on rigs around here.

 

[Landon730]

Took the gauge bezel out and firgured out the hvac control head actually came apart. The mode switch litterally fell apart. Put working control head in and its working now.