1998 Chevrolet Tahoe Blower Failure

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BZAG00
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  • 1 POST
Lately I've been getting blower failures in my front heater (same as A/C). Typically when starting the vehicle the blower works, but when I shut it (and the engine) off and later start the vehicle and turn the fan back on the blower (fan) does not work no matter what position the fan switch is in. The A/C is working (detectably audible) and the vent controls are working (also audible). Occasionally the fan will just turn on by itself if the switch is not set to OFF. Also, leaving the switch on any ON setting has been giving me 85% success rate in getting it ON after turning the vehicle OFF and then ON again. This all sounds to me like a relay problem. I don't have any wiring diagrams and would like to know where I can get them. I've seen some web sites but I'd like your opinion on getting them, and also on the diagnosis. I've found some harness parts sites like at rockauto.com that indicate the relays are actually embedded in the harness (!) I'm over 50, not a mechanic and this type of thing is new to me; are the relays really in the harnesses? Or am I seeing things? I'm determined to understand this (for once !). THANKS. BZ.
Feb 2, 2007 at 5:36 PM
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2CARPRO JACK
  • ✓Experienced Mechanic
  • 11,533 POSTS
Grab a test light. When the truck is running and the blower isnt working, test for power at the blower, if it has power, check the ground, If ok then it sounds like the blower motor is goin out
Feb 3, 2007 at 12:53 AM

Suggested Repair

With the engine running and the blower not working, test for power at the blower motor. If power is present, check the ground. If both power and ground are good, the blower motor is likely failing and should be replaced.

Conversation Summary

The owner of a 1998 Chevrolet Tahoe described intermittent front heater/A/C blower failure: it often works at first start, then fails after the vehicle is shut off and restarted, sometimes coming on by itself. The owner suspected a relay and asked about wiring diagrams and whether relays are embedded in the harness. The expert advised testing for power at the blower when it is not working, then checking the ground; if both are good, the blower motor is likely going out.

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