Blower motor acting up on "high" setting

Discussion in 'General Chevy & GM Tech Questions' started by alchemist1, Aug 23, 2009.

  1. alchemist1

    alchemist1 Member

    My 1998 Suburban has had a couple of problems for a while. Here's the long and short:

    1. the front blower seems to really be weak when pushing air out of the vents. Much weaker than it should be. I tried running 12V straight to the fan blower lead and no improvement. Also, I cleaned out the evap case (bugs, leaves, grime) and really cleaned up the evaporator too. No help. any suggestions?

    2. the blower works fine when on any speed EXCEPT high. Sometimes in high it shuts off, or sometimes it doesn't start at all. When you bump the fan blower case under the passenger side dash, it will usually come on. I did some diagnostics on the wires, and found out that the red wire that comes from the blower relay (the relay only feeds the blower on high setting) is warm or hot to the touch on either side of a black connector. The black connector was also very hot!! when I disconnected the black connector and looked into either side (male and female), there was some evidence of melting of the plastic frame insde the connector. I just replaced the blower relay too. I'm wondering if I should basically just replace the black connector, or do I have a ground problem??
    Last edited: Aug 23, 2009
  2. bill190

    bill190 Rockstar 100 Posts

    I always look at a wiring diagram to first understand how it works.

    Some units have a "blower motor resistor" which is a typical problem.

    Others work differently.
  3. 5speedsilverado

    5speedsilverado Epic Member 5+ Years 1000 Posts

    i have the same problem on my 06, the red wire draws 15 amps when it is on, and my wire actually melted, me and my dad when it cools off, we are going to track down the wires and replace them with a thicker gauge wire. dont use the high setting any more till you get it checked out, their have been fires from this problem
  4. alchemist1

    alchemist1 Member

    15 amps? It may supposed to pull that much on high, not sure. Sounds a little high though, and that could mean that the blower is pulling too much (e.g. on its way south)...

    I'm thinking it is simply just the connector not allowing the two reds to make good connection. Lot of juice flowin through this wire.
  5. 5speedsilverado

    5speedsilverado Epic Member 5+ Years 1000 Posts

    yep, we thought that was high also, so when it cools off were going to be replacing it with a thicker gauge wire. we used something that reads the amps, that my dad had for work to find out what it was pulling
  6. RAMwoodworks

    RAMwoodworks Member

    I have an '06 Sierra WT that had the same problem. There is a bulletin from GM on this.

    You can buy a harness here or at you FLAPS.

    I replaced the resistor and patched in the new harness two months ago and yesterday it crapped out again. Same problem as before the ground (black) wire contact to the resistor was burnt. I cleaned it and it is working again but there must be more going on. I'm thinking that the motor might be drawing too much or the resistor is poorly designed.
  7. Loggerhead Mike

    Loggerhead Mike Rockstar 100 Posts

    the resistors taking a dump is a very common problem on our silverados tahoes burbs.

    when the blower wont work on high speed, replace the jfuse under the hood. The fuse doesnt always have a visible melted lead. if that doesnt fix it, it is a guarantee your resister dumped out, wich takes the wiring harness (usually melting the ground) with it.

    any dealer has a wiring harness that you just splice into the origional. There around 20 bucks.

    You said your wires melted again after replacing the resistor? did you use a gm resistor or aftermarket? make sure there is no water coming into your hvac unit (evap drain clogged). if none, its just a matter or a poor designed part. ive had "new" resistors not work correctly out of the box
  8. RAMwoodworks

    RAMwoodworks Member

    I went with an aftermarket harness and resistor, $75 for both. The harness wasn't color-coded but had a thicker guage wire. The resistor was identical to the factory resistor - made in Slovenia.

    FWIW my BIL talked to a service rep at the local chevy dealer who said they ocassionaly get a truck that will come back after 6 months even using the 'factory' repair parts. Others get fixed once and never come back.

    I'm considering pigtailing the ground and running direct to the body to hopefully prevent another failure. Any idea what kind of Amp draw the blower should have?
  9. 1slols1

    1slols1 Rockstar

    where did you get it from?????
  10. RAMwoodworks

    RAMwoodworks Member

    I got the resistor from Auto zone even though the one the computer called for was wrong the guy found the right one. The right one for my Sierra WT was DR755.

    My BIL got the harness from Associated auto parts.

    If you just google "GM blower harness resistor" you'll find plenty of online suppliers for around $75.

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