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Blower motor resistor or control module?

106K views 44 replies 27 participants last post by  eihab 
#1 ·
Ok so I am experiencing some intermittent fan issues with my heater and with pretty constant 0-20 degree weather that is no good. So I was looking around and saw issues with blower motor control modules and blower motor resistors. Can anyone tell me which issue I am having so i can order the right part? I do have the automatic hvac controls and even if I turn on the manual control the fan does not respond but it will come on just not at any certain time. Thanks for the help!

Nate
 
#3 ·
Probable Fix For Blower Motor Problem

I had the same intermittent blower motor problem on my 2003 Trailblazer, and I replaced the Blower Motor Control Module and it fixed the problem. I also have the auto HVAC. The blower motor would run for a while even with the ignition off. It would not work in any manual settings. I purchased the Blower Motor Control Module at my local Chevy dealer and paid $90.00. It was easy to replace. I hope this helps!

Dave
 
#4 · (Edited)
Hi Dave and thanks for the response. Is the Blower Motor Control Module the actual motor, or the resistor, or another part entirely?
I don't want to purchase the wrong part and not be able to return it because it's an electrical item.
Appreciate it,
Happy New Year!
Here's a link to a pic of what I've been calling the resistor.
http://webcaps.ecomm.gm.com/servlet...name=ACDELCO&prodlinecd=15&acpartnbr=15-80186
 
#5 ·
Hi Jay, the blower control module is installed in the lower area of the heater plenum and it looks just like the picture you provided. The local Chevy dealership first tried to sell me the resistor type module for a manual system which looks different and is a lot cheaper. Have a nice day.

Dave
 
#7 ·
Always check the wiring harness at the time you replace the resistor or module. The wires have been known to have an issue with breaking and causing much of the same problem as you describe. The dealer may tell you to replace both if you replace the resistor/module as they say the problem can be related.:m2:
 
#8 ·
Hey more great advice. To clarify I assume you mean the plug that goes into the module. If its not looking to good and needs to be replaced is it a matter of soldering in the new piece or does it come as a whole length which gets plugged in on both ends?
 
#9 ·
I looked at the plug on my TB and it just seems like it isn't staying tight in the module. I can move it around and turn it on and off. Is that just the module or the plug itself??
 
#10 ·
2003 chevy trailblazer blower control module

where is this located i believe this is my problem. i have automatic setting. My blower will run low no matter what i put it on in manual settings. I can restart the car and sometimes get it to go to high or it will go to high whenever it wants to.
 
#14 ·
I had a similar problem. My heat was working only on speeds 1-3. I spent a hour reading these forums and was able to determine it was the resistor pack that was spoke of. Brought the resistor pack this mourning from the dealership for about 60. Installed it in about 25 min. Would have been done a lot sooner but the harness had actually melted in a few places so it took a while to pry it off. Will be buying a harness from the junk yard eventually and soldering it on. The dealership wants 200 for the harness. I would like to thank everyone on this form. The pictures and description of where it was located was great.
 
#15 ·
Hello everyone, i been having this same problem with the resistor and the wiring harness. My harness is also burnt at the end and melted the resistor. So does anyone know why the harness gets so hot that it melts the resistor, and how can i fix this? Thanks in advance for any help and replys.
 
#16 ·
Harnesses get hot because of high current going through the connector that hits a bit of oxidation or atmospheric corrosion that causes a bit of resistance. Resistance causes voltage loss that turns into heat. Heat that goes on and off with the vehicle running and being turned off causes small amounts of thermal expansion and contraction that in turn causes more and less contact force inside the connector that in turn causes a higher resistance and that makes for more heat that makes the entire problem worse and worse until the connector finally heats up enough to melt plastic, wire insulation, or discolor the wire. It's a snowballing phenomenon once it begins.

Gold plating reduces these effects, but not the tin plating on most automotive connectors.

I've been studying aging electronics systems for most of my 35-year engineering career, and connectors are a specialty of mine.
 
#18 ·
99.9% of vehicles don't have a failure like this. I wouldn't worry about gold plating. But I always laugh at the audiophiles who think they get better performance out of gold-plated audio or video connectors. Unless it's a real thick plating, it scratches right off of the high spots in the connector when they first put it together. And it's only the high spots (microscopically) that are touching. But that's another technical debate for another forum. :yes:
 
#20 ·
I dont mean to hijack the thread, but this looks like it could be a good time to ask about the rear heat and cooling.

Where is the resistor pack for the rear blower. It seems like my rear blower is intermittent and I am guessing that this could be my problem...right? Secondly, I also seem to have problems getting air to blow from the top vents and the floor. I hear the blower working, but can't feel the air from the top or the bottom. It's like the air is getting lost somewhere. Any ideas?

thanks for the help and apologies for a potential hijack.
 
#23 ·
Where is the resistor pack for the rear blower. It seems like my rear blower is intermittent and I am guessing that this could be my problem...right?
The rear blower is electronic, and the speed isn't controlled by a resistor pack, if I'm reading the shop manual correctly. I have the SWB, so I don't have the same sort of control system. When you say intermittent, can you explain what happens when it fails, and how often? Are you using the front speed switch to control it or the one in the rear?
Secondly, I also seem to have problems getting air to blow from the top vents and the floor. I hear the blower working, but can't feel the air from the top or the bottom. It's like the air is getting lost somewhere. Any ideas?
That is a classic problem with the mode actuator behind the dash. Run a search. You can replace it, or an HVAC reset might clear the problem. Pull rear fuseblock fuse 36 for a minute. Then plug it in, turn on the ignition, and don't touch any HVAC controls for a minute. You should hear some actuators move about, and stop after a while. See if this helps. If not, you need to troubleshoot the mode actuator.

The vent issue sounds like it could be a broken vacuum line. I'm pretty sure vacuum pressure controls the vent doors.
Not in trailvoys. Totally electronic motor-driven controls using actuators with feedback to tell the control module the positions.
 
#25 ·
Only blows on high

I have a 2005 TB with the automatic HVAC system. If I set the blower to the lowest - 3 settings, the blower blows very hard. It almost seems like settings 1 -3 are the same as setting 4.

This does not seem like a resistor since the blower actually works on settings 1 -3, but I'm far from an expert. Can anyone help?
 
#26 ·
Hi, it's most likely a blower control module. When this fails it causes weird problems, such as: blower runs constantly with the ignition off (key removed), intermittent operation with variable blower speed. On my 2003 Trailblazer (auto HVAC), my blower motor ran with the ignition off (it would stop after a few minutes). Replacing the blower control module fix it. The blower control module is a known problem on Trailblazers also. No guaranties that your blower control module is bad! Have a nice day. :)

Dave
 
#27 ·
blower motor control module

i understand that i swing the glove box down and the do i take the shroud off of the blower motor so i can see the control module or it there a different plate i have to remove before i can even see this part. Any info would be helpful. Also if someone know where i can get a picture of the area and parts there as a guide.

Thanks
 
#30 ·
Hi,
You have to stretch yourself on the passenger seat with your face up. Look up behind the gloves compartment and search for two hexagonal headed bolts on the lower side of the blower box. You'll need a 5.5 mm wrench to loosen the bolts. My advice is to open the module and resolder all it's inner parts. There's a hidden screw under the part information sticker. You'll have to remove it first. Make sure you apply new gum on the main transistor before closing the module box.(gum like the one we use between the heat sink and the processor of the personal desktop computer). It might work as mine did. If this doesn't work, then you go and get a new one.
Don't forget to solder the contact points where the plug connects to eliminate the posibility of loose connection.

I hope this helps.
 
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