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84 C10 blower won't come on

Landon730

Active Member
Messages
192
Likes
115
Location
Greenwood Arkansas
Thread starter #1
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.
 

3500GMC

What T F, over
Messages
5,469
Likes
603
Location
Nashport, Ohio
#3
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

Active Member
Messages
192
Likes
115
Location
Greenwood Arkansas
Thread starter #5
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
 

3500GMC

What T F, over
Messages
5,469
Likes
603
Location
Nashport, Ohio
#7
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.

Well-Known Member
Messages
8,196
Likes
7,519
Location
Boulder City Nv
#8
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.
 
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