Hvac Fan Control

[bandit01]

Need some help on my HVAC fan control. Fan recently decided to operate only on speeds 3, 4, and 5 ( 1 and 2 inop). Then today, the fan went into the high speed mode (5) on its own, with no input at the control. Fan runs on high regardless of speed setting. It also continues to run on high, even when the engine is turned off and the key removed. Obviously this will present a battery drain problem. Not sure where to go; my first inclination would be either a rheostat or some sort of short to ground. Anybody seen this before or have any ideas? Thanks, Dave

[SilveradoLS]

Check your blower motor resistor.

[bandit01]

Check your blower motor resistor.

OK, thanks. I'll let you know how it works out. Dave

[croberts]

Common problem, hopefully your connector is not burnt, that takes more time and money. The resistor is plug and play, moisture and heat break them down, had the same problem twice and found water on the resistor when I pulled it. The high speed is a direct 12v feed from the battery, you probably have a short causing direct feed. Pull the fuse under the hood for now, when installing new resistor you may want to brush on some oxi-guard or similar anti corrisve compound for electrical connectors on the solder joints, mine rusted and caused the short. S**t design.

[SilveradoLS]

I just had to do this on my truck Sunday. Thing started intermittently cutting out, then just quit all together. When I pulled the cover under the dash where the resistor is located it jumped right out at me, the plug was melted and one wire had the insulation melted off of it. Got a new resistor and spliced in a new pigtail connector. One thing I noted was that the new pigtail had much heavier gauge wire than the OEM harness did so hopefully this will take care of that for a long time to come. Like the other posted noted, my OEM resistor had corrosion all over it from condensation.

[bandit01]

Thanks to everyone who offered help. It was the resistor...replaced and all works as normal. Noticed the plastic covering on the original resistor was flaking off allowing moisture in. Connector was fine and everything else was clean and dry. Silverado LS--I did notice the wire gauge had increased on the replacement part. Guess I was lucky nothing got overheated and melted. Thanks again! Dave

[SilveradoLS]

Glad you got it all fixed up.