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

When the connector shows heat damage, you need to replace the resistor and the connector at the same time.

 

Power to the blower is from a 50 Ampere Heater Fuse through the Heater Relay to the blower motor to the resistor bridge to the AC Controller to Ground. There is one parallel leg with the blower that goes to the AC Amplifier on this same 50 ampere fuse.


I'm thinking a defective blower motor that isn't cooling the resistor as it should. That is why the resistor keeps burning out. Note that the resistor is in the duct where the blower discharge is blowing on it all the time when running.

 

In your picture it shows 2.4 mV Not Volts.

See here for the complete picture:

https://www.customtacos.com/tech.ol...toyewd/06toypdf/ewd/2006/tacoma/h/em01d46.pdf

 

50 amp fuse for a blower motor? I guess that's why the connectors are burning up. I'm going to put an amp clamp on mine out of curriousity.

 

The highest current I see on any of the four resistor leads is 11.1 amps. That should be M2. It looks like the blower switch provides series or parallel combinations of those three resistors to control the blower speeds. High bypasses the resistor module. It could be that the resistors are not being cooled sufficiently by a dragging blower motor or overheating due to bad connections or both. I assumed that bower fuse to be 15 amps so 11 amps is what I would expect in that case.

 

Alright, based on the replace melted parts feedback, I went ahead and ordered a new,

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HVAC Fan Blower Motor Resistor With Wire Harness Replace # 973-582 for 2005-2017 Toyota Tacoma

$18 Allmotorparts HVAC Fan Blower Motor Resistor Kit with Wire Harness 973-582, 87138-04052, 8713804052, RU746, RU1435 Compatible with Toyota - 2005-2020 Toyota Tacoma - Manual AC Control & Oval Connector

https://www.amazon.com/gp/product/B07H34RRPX/ref=ppx_od_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
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If the overheating issue is, in fact, the burnt cable connector that should solve the problem.

I will install the new harness with the new cable connector and measure the temperature of the new resistor and report back next week with my results.

Thanks for the support.

~ 0000

 

It is clear that the blower is supplied by the 50 ampere heater fuse through the Heater Relay see the below linked schematic.

https://www.customtacos.com/tech.ol...toyewd/06toypdf/ewd/2006/tacoma/h/em01d46.pdf

There is also a parallel circuit to the A/C Amplifier that has an additional 10 ampere fuse and controls power to one of the Servo motors.

 

Yes, it was clear after seeing the wiring diagram, thanks.

 

Ok, I replaced the, ac controller unit, wiring connector, and blower motor.

With the new parts, the system is functional however one problem still persists which is:

The Blower Resistor heats up like a hot plate when the system is on.

I tried both the original resistor and the new one and both had the same overheating problem.

1. A film of test #1 new resistor;https://youtu.be/UmunijK9vHA
2. A film of test #2 original resistor; https://www.youtube.com/watch?v=Sd2D-nj5jEY

Tocomaworld community, any thoughts additional troubleshooting strategies which could help me understand what is causing the overheating problem of the fan blower motor resistor?


Thanks,

~ 00

 

I can tell you exactly why the resistors are getting hot.

The resistor pack is inserted into the exhaust duct work from the blower for a very good reason and that is to keep it cool.

You are running it with essentially No Cooling at all. It has to dissipate the energy that is not being used by the motor and it does that by generating heat. This heat is normally carried off through the air flow in the system.

 

This I learned today, the resistors are supposed to be hot!

I will run it as following the factory install and hopefully, it will not burn up again. It makes sense that the 50amps dissipation creates heat on the plate.

I am still not sure if the old wiring harness caused the first replacement resistor to fail though?

Definitely room for Toyota to innovate on this desigen in future products. That explaines why the old whiring harness melted, the air cooling was not enough to protect the coupling itself.

The original resister must be able to take the heat though as it is been operating find for the last 190,000 miles.