Need some help - 1997 Tahoe Heater / Blower Motor

[MarcelMarechal]

Hey guys, hope all is well. When I turn on the blower to defrost my windows it doesn't work. I checked the fuse and it was toast so I replaced it. Then it still didn't work. SO I switched the starter and blower relays and then it started to work again for a while. Now it did the same thing and stopped working but I find it will randomly turn on and off by itself when I am driving but never works when I want it to. What do I do here?

 

[waveryd]

Drop the glove compartment and check the resistor which looks like coiled wire between two posts and ensure that they are intact and current passes through them with good connection. Also check the speed switch carefully by changing speeds slowiy to ensure the switch has good contacts. I had a '96 Suburban with 600k miles and had issues with both over the years. Lastly, hot wire the blower motor and wiggle test everything. Moisture and corrosion can take its toll over the years. If you suspect the motor you can swap the blower motor from the rear hvac unit to front to verify.

 

[OR VietVet]

Welcome to the forum.

Yes, like @waveryd said, check resistor and switch and even the blower to see what it does with direct power. Remember that the blower, I think, is supposed to run at a very low speed at all times for air circulation but on this rig, maybe not. Whatever you do, and figure out, use all new fuses and relays.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[Hoesgottaeat2]

The switch in the dash is often a culprit with symptoms you describe as well. Replacement is pretty straight forward. Be sure to rule that out as well, if you haven't already.

 

[Eman85]

My money is on a melted connector on the blower switch. You can check power and ground at the motor first as it's easy to get to and then check the relay behind the glove compartment.

 

[Mean_Green]

I have a similar issue and will be checking all of these things. Planning a trip to a salvage yard, so might be able to pick up a switch if necessary.

Does contact cleaner work on them or are the contacts sealed?

Blower's a bit noisy too. Sounds like a rattle of some kind. Might grab one of those if possible.

 

[east302]

On the three that I’ve had, it was the connector on the blower switch (at the panel) that melted and caused the switch to work intermittently. It’s worth a quick check. You can buy a pack of the connectors and change it out. GM part 12064998.



Wiring diagram for a 98…



For the noisy blower, if there is rust on it then you likely have a water leak in the windshield cowl. Stick a mirror up inside the blower intake duct and you’ll see a self-tapping screw popping through the cowl. Water can leak in there (a then onto the carpet) so pull the screws on the cowl plastic and seal the holes up before reattaching. The blower would probably best then be replaced, but that’ll take care of the water leak.

Clean out the housing to the left of the blower at the evaporator while you’re at it. It gets gunked up pretty easily and reduces the airflow. Self-rinsing foaming a/c coil cleaner works pretty well.

 

[j91z28d1]

On the three that I’ve had, it was the connector on the blower switch (at the panel) that melted and caused the switch to work intermittently. It’s worth a quick check. You can buy a pack of the connectors and change it out. GM part 12064998.

View attachment 395269

Wiring diagram for a 98…

View attachment 395268

For the noisy blower, if there is rust on it then you likely have a water leak in the windshield cowl. Stick a mirror up inside the blower intake duct and you’ll see a self-tapping screw popping through the cowl. Water can leak in there (a then onto the carpet) so pull the screws on the cowl plastic and seal the holes up before reattaching. The blower would probably best then be replaced, but that’ll take care of the water leak.

Clean out the housing to the left of the blower at the evaporator while you’re at it. It gets gunked up pretty easily and reduces the airflow. Self-rinsing foaming a/c coil cleaner works pretty well.

yep, mine melted years ago. the oem blower motor started to get hard to spin and draw more current is what I think was the cause after all way said and done.

I tried 2 auto parts store blowers, both were noisy. ended up ordering a oem one, it was quiet and the switch plug never melted again.

for me the one setting below max speed melted, it was also the most commonly used.

 

[Mean_Green]

OP never returned.

Finally got a chance to dig into a few things.

Blower does not run (that I can tell) in any position other than High. And even then it doesn't sound right. Almost like something is loose.

Pulled the blower motor today. It's a Napa replacement, who knows from when, but it's all clean and tight. It does not spin freely by hand, but it isn't bound up either. When I connect it straight to a battery, it blows up a tornado. Wires that connected to it are OK, but the plastic shields over the 1/2 tab connectors are melted, ground is worse than 12V.

Resistor looks good to the eye. No discoloration or deformation. Wires and connector look good too.

Climate control appears to have been replaced at some time. Connectors are all good though, no signs of overheating.

Before I order a climate control, is there anything else to check?