A/C Blower will not come on

DANC.

MEMBER
1998 CHEVROLET SUBURBAN
0.7L
V8
4WD
193,552 MILES

First A/C comes o and is cold, but blower motor on AC just quit, but sometimes it comes on at low speed. But now not at all.
Here is what I've done:
-Replaced AC controls in dash, no difference
-Replaced blower relay, old one would click
at high setting, new one clicked at high
setting, still no blower.
-Tapped hard on blower and came on for a
second then stopped, so I replaced blower,
Still doesn't work, cannot get it to come on at all. Now blower relay no longer clicks on high setting.
-I ran jumper wire from fuse box to blower motor and blower works.
-Pulled and replaced Blower resistor, still. .
blower wont work.
-I have checked all connections, no wires or
plugs are loose or burned.
What have I missed. Help! Thanks, Dan

2 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

This could be a problem with the red wire coming from fuse #3(50A) in the Under-hood Fuse Relay Box to the High Blower Relay on top of the front of the A/C-Heater Box. The best to do this is with your vehicle running and the blower switch on high. Then do a voltage drop test. To do this get a jumper wire with an alligator clip on each end. Place a paperclip in the fuse #3 and attach one end of the jumper wire to it. The other end attach to the red lead on your multi-meter. Back-probe the High Blower Relay connector at the red wire with the multi-meter set in 20V range of DCV. There should be 0.1V reading. If OL reading there is a break in the wire. If the reading is more than 0.1V there is damage to the wire causing unwanted resistance, Either way replace the red wire. If you get a reading of 0.1V then test the purple wire from the relay to the blower motor connector the same way. If the purple wire tests okay then replace the 5 Pin High Blower Relay. If purple wire is bad replace. This should fix your problem.

Thanks,
Alex
2CarPros