Resistor, blower motor or wiring? What's going on?!?!

The heat and A/C stopped working in my 2007 Tacoma. First only worked on high and then not at all. I pulled out the resistor (which was rusty looks pretty bad) and replaced it with a new one. Awesome! It works! A/C and all! Wrong... two days later it died again. Could this be an electrical problem or is my blower motor spent? It seems odd to me that the motor would work with a new resistor but only for a hot second. Ideas?!

 

Blower is likely shorted and drawing too much current. This fries the resistor repeatedly. It has sort of a fusible link built into it by design and when they fry you lose all speeds except hi.. Look closely for melted connections too!

 

But no speeds are working. And looks like connectors are all good. Is there one specific connection point I should look at? Or check the fuse?

 

The wires are probably melted at the blower motor connection. Common in these trucks

 

Awesome. Thanks. Will report back.

 

Sometimes the pins on the harness to the resistor are bent slightly and not contacting like they should. I would look for one to be bent down a little. Spray the resistor and connector with electrical cleaner then with a q-tip lightly coat it with dielectric grease. That should keep the arcing and carbon build up down which will ensure a clean connection.

 

Replace both resistor (again) and blower motor..

 

No. Dielectric grease is an insulator. It is meant to seal connections to keep water / moisture out.

http://www.polysi.com/polysidielectricgrease.html
Dielectric Grease Applications:
Spark plugs (rubber boot of the plug wire), gaskets of multi-pin connectors in car and marine engines, rotors, distributor caps, speedometer cables, outdoor lights, trailer hitches, battery terminals, satellite TV dishes, coaxial cable, power utility high and low voltage connectors.

Dielectric grease. Dielectric grease is electrically insulating and does not break down when high voltage is applied. It is often applied to electrical connectors, particularly those containing rubber gaskets, as a means of lubricating and sealing rubber portions of the connector without arcing.

 

Pull the electrical plug that connects to the blower resistor. Almost certain you'll find that one of the connectors in it is discolored and possibly melted! It's a very common problem. If you look on eBay you'll find both Toyota dealers selling OE replacement electrical connectors, and aftermarket kits made by Dorman with all the pieces needed to fix it. Been there, done that!

 

While you are correct that it is an insulating grease, it keeps oxygen away from the connection. The 2 surfaces push the grease out of the way and make contact but seal the connection so no arcing (corrosion occurs). I've used it for connections like this for decades with positive results. I especially like using DEG on trailer connectors. I know that this is another controversial subject like anti-seize on lug nuts. I will continue to do both.

 

So all of the electric call connectors looked good. The fuse was also fine. I pulled apart the motor and cleaned it. There was a significant amount of copper shavings. The brushes, which are spring loaded were also stuck and unable to move freely because of the resistance. I suspect this was the main reason the blower was not working. Long story short, it works...for now at least. It was pretty worn so I suspect will need to replace relatively soon. Below is a great instructional page. Thanks all for your comments!

http://www.ncexped.com/tacoma-fan-switch-not-working/

 

Same thing happened to me I had to splice in a new wiring harness with a new connector for the resister.

 

Same issue here. Here's my thread on it.

https://www.tacomaworld.com/threads/ac-control-wires-hot-melting-plastic-behind-dash.446790/

 

Hey guys. Love this site! Read all the threads here and have decided I need to replace my blower and connector to the blower since it's badly burnt and melted. I found the blower on Rock Auto but I can't seem to find the connector. Can someone point me in the right direction?

 

I got mine from the dealer.

 

I am having the same problem.
2006 tuck with 186,000miles
Replaced the relay it the new super hot to the touch and only lasted two days. Put the only one back in which seems to be working on with the controller set to high, however, the blower motor runs very very slow. Just enough to defog the windscreen.

Just purchased a new motor off Amazon. Will install and report back if that works.

$31 HVAC Plastic Heater Blower Motor ABS w/Fan Cage ECCPP for 2005-2013 for Toyota Tacoma

https://www.amazon.com/Plastic-Heat...automotive&vehicleId=1&vehicleType=automotive

Link to album: https://www.tacomaworld.com/media/a...g-blower-motor-wiring-resister-problem.50914/

 

Your pictures are confusing and seem to be repeating.

For the new resistor you keep saying that it won't pass current but the meter is set to resistance.

The Last picture you say it is running current through the connector when the meter is set to Voltage and showing 2.4 millivolts.

Granted the resistor should show various resistances depending on where you place the leads. See the drawing below to see where the pins should be. Your guess is as good as mine about what the various resistances should be as they are not specified in the prints.

Also there should be voltage at the blower whenever the truck is on through the heater relay. The resistor controls motor speed by inserting a resistance in the ground leg of the blower motor.

 

Jimmy,

Good point. Let me clarify.

My goal was to use the multimeter to troubleshoot the parts in the system in an attempt to identify what was and was not working and to choose the next best step based on the results.

1. I used the resistance measured in ohms on the multimeter to verify that electrons move through a conductor, in this case, the;

a. old original resistor has a resistance measurement of greater than 0 or 2.8 Ohms. I believe this is an indication that it may still be functional. So I am going to keep it for now.

b. the new resistor, which seemed to overheat for the short time it did work has resistance measurement of 0. For this reason, I am going to stop using this part after I install the new blower.

2. I choose the voltage meter measurement in DC = Direct Current of the cable connector from the wiring harness because I could easily take measurements while using the AC controller unit to send power to the cable connector while the truck was running. Despite the burn marks on the cable connector voltage did flow. In the photo included in the post, we can see that the voltage is at about 2.4v. In another measurement of the fare endpoint of the connector (not photographed) I received a reading of 12v.
I believe this is an indication that both the wires and connectors are working and for that reason, I am not going to replace this part yet.

3. The blower is the weird one. It is functional with a new resistor. However, I am not sure how to test whether or not it is causing the resistors/wires to overheat. For that reason, I am going to buy a new one install it and check the temperature of the wires, connector, and resister after install.

Hope that helps clean things up.

Thanks,
~ 0000

 

Find out, from the owners manual ,what fuse is supplying the blower motor. Take its rating and multiply by 0.8. That should be about the maximum that motor will draw continuously when running on high. Connect a DC AMMETER capable of measuring that amount of current, in series with the motor, and see what it is drawing. That will give you a good idea if you are exceeding the wiring capacity. If too high verify that all connections are clean and tight and the motor is not rusted or has worn ,dragging bearings or brushes. My resistor connector was burned. I replaced it with a Dorman resistor/harness, works fine now.