Heater issues

[Tahoe442]

Alright guys when I have the heater on high it intermittently makes a noise like its switching locations from where its actually blowing. Also when its on, especially high it makes a weird noise kinda like a buzzing noise...super annoying. Any ideas on what this is?

 

[SunlitComet]

Well the high mode switches from the resistor ballast to direct voltage feed via a relay. I would inspect both of those to start. They are behind the glove box.

 

[mulloo]

I have had a similar sound coming from my '97 Tahoe blower as well, although it would be on any speed, not just high. I just upgraded the stereo deck to a new unit and changed the lightbulbs on the hvac control unit only to find that the HVAC only works intermittenly. Probably just a coincidence, but does anyone have ideas if I just need to replace the blower motor, or is it more complicated?

 

[SunlitComet]

Ensure the connector on control head are fully attached with no contact arcing or burnt wiring.

 

[mulloo]

Ensure the connector on control head are fully attached with no contact arcing or burnt wiring.

Will do and will report back! Thanks for the quick reply!

 

[Tahoe442]

Sunlit I had replaced the resistor on mine and the problem seems to be resolved. Thanks for the help!

 

[mulloo]

Pulled the HVAC controls and swabbed the contacts with some alcohol wipes. Reinstalled and all appear to be working normally. There was no evidence of no evidence of arcing or burning on any of the connectors and wires. I'll continue to monitor.

Over the weekend I spoke with a salesperson at Advanced Auto who said that the fan is a known issue with the late '90s Chevy's. He said that it would stop working he would just kick "up" under the dash on the passenger side to restart the fan. Works every time he says. Sort of a funny low-tech fix, but still not a fix.

Separately, I broke one of the clips for the area selector this time when I removed it. I guess the plastic gets a bit fragile and dried out after 17 years! Other side still has the locking clip and it appears to be making good contact.

Tahoe442 / Sunlit - Is changing the resistor a big deal? What is involved as my heater does make a similar sound of changing and occasionally makes the low groaning sound referenced in another part of the forum.

 

[SunlitComet]

You have to remove the glove box. And you might find it best to use stubby drivers perhaps.