Fan control and blower resistor harness burnt

I know how it works. I change heating rods on our rubber injection molding machine. I just didn't think that the fan speed selector connection was also bad.

Just how many other electrical issues should I expect? If I'm going to be back there to make sure the contacts are connected then I might as well.hitnup any other possible loose ones as well.

 

Some people have suggested that a plugged up cabin filter or a worn out blower motor cause the motor to draw more current than designed and lead to burnt connectors. Nobody has done current draw tests to confirm this though. My opinion on this is that if just the resistor and connector cook, just replace the resistor and resistor connector, but if the motor and/or switch cook, it might be a good idea to replace the motor. That's just my opinion though.

 

When I change out my center support bearing I'll take the truck into work and hook up an amp meter and see what the pull is at the blower motor and at the resistor.

Hopefully I can find readings of a good motor and compare them.

However, evidence is showing this may have been a clogged filter.

• Burnt resistor
• Burnt resistor pigtail
• Burnt fan speed selector
• Brand new filter with little to no dirt
• Debris stuck above the intake duct
• Dirty blower

It looks like the previous owner may have brought it in to the dealership and all Toyota did was change the resistor and filter........ugh

Time to get the Fluke ready.

 

A blocked fan or blower will draw less current, not more current. Less work = less current required.

http://hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html

The amp draw on a centrifugal fan goes down as resistance to airflow is increased. For most people this seems counterintuitive. It is easy to picture the fan motor pushing harder to overcome the resistance and increasing in amp draw. However, this is exactly backwards. Centrifugal fans move air by throwing the air outwards through centrifugal force. The amount of air the fan is moving decreases as the resistance to airflow increases. If the fan blades are moving less air, they can actually spin easier because there is less air to sling. This causes the motor RPM to increase and the motor amp draw to decrease.

 

That is so backwards from the oil heaters we have. They have centrifical pumps. And the way to set the motor amp load is to close the flow valve complete hook up an amp meter measure it and start opening the valve until you hit the proper amp load. Fully closed gives you full amps. Then again fluids dont compress so there's that....lol

If a clogged fan only prevents the resistor from cooling, then it had to be loose contacts?

Also, how hot does a resistor get? I don't see how full heat can keep the resistor cool unless it's hotter than 200F.

 

This seems to be a hard concept to grasp. Yes a blower resistor will last about 30 seconds with no air flow. The old wire wounds would glow bright red just before they burn up.

 

Yes it is a great deal hotter than 200* Loose contacts creates high resistance high resistance equals heat. What happens to squirrel cage blowers they cavate with no air flow so because they can move no air they turn faster because there is less resistance. Pumping fluids is a different kettle of fish a centrifugal oil pump has veins they are off centered the rotation throws the veins out into the wider point of the pump (suction side).

 

Here is the deal to save copper they use marginal wire gauge, to save room they use smaller connectors with more wires believe me when I tell you this is nothing new it has been going on for years, shoot I quit working on vehicles to make a living in 96 and decades before that they were burning up heater wiring long before Toyota even existed. Maybe in the future they will go to brushless motors with considerable less current demand.

 

Yes, loose contacts.

The air flow flows across the resistor before it is heated by the heater core...

Air Inlet >> Fan Blower >> Speed Resistor Pack >> Heater Core / AC Evaporator Core >> Vents in Dash.

 

That's what I was missing. I'm a visual learner so I need to "see" things to understand it and the flow was what I didn't see. Now it all makes sense. So the resistor is fine. The small corrosion I'll take of later. Since the winter season is pretty much done I don't have to worry about airborne salt in the moisture as I'm driving.

I'll make sure to double check the contacts and bend any that may need it. Carefully of course.

 

These are for the blower motor and resistor pack. I don't have any information on the AC Controller connector.

Resistor and connector needed:



Look at both connectors on the motor. I'd be willing to bet one or both of them are burned.

If they have burn marks you need to replace the connector plugs.

Part number

$13 90980-10916 6" 12ga Harness New

90980-10916 Connector

Part Number

$10 82998-12380 90980-10916, 6"es 12 Gauge Wire Harness

82998-12380 Wire and terminal

Not sold as a kit, sold as each. So you will need one of the plugs and two of the terminal and wires.

Connector:





Terminals:

 

Carp. That harness looks like what I have on mine. But I don't see any buttconnectors or splices. I'll double check another post that shows what the old and new ones look like and doublecheck that the TSB wasn't done on this.

I wonder how many people had this issue happen again after the TSB.

 

Doesn't look like it's the new one. However, there isn't much tape under there so someone has been playing around. I'll give it the once over one more time when my 4400NEX comes in and I have to take everything out again.

 

I replaced the resistor and pigtail a few years ago and this is just now, the resistor connector and fan connector.

The stuff I ordered to replace the AC Control Panel connector is coming from China so it will be a while before it arrives.

 

Jeez, talk about timing. As of today, my fan only runs on the high setting. Probably because I rarely run it on high, those terminals may not be burnt. Guess I know what I’ll be doing this weekend. Previously had a mouse nest on my filter before I did the screen fix to inlet opening, so, yes,high air resistance my have been contributing factor.

 

No, see my link above. Blocked blower draws less current not more...

Replace terminals connectors and resistor assembly and you will be back to normal.

 

Think I got lucky this time. Unplugged the connector, did not see any burn marks so I wiggled it back on and now fan is working again. Guessing I had just enough corrosion to prevent connection but wiggling it back on rubbed enough off to get it working again. Thinking I should still get a new heater resistor since if there is that much corrosion, it will just be matter of time before it over heats and burns out and maybe next time take the connector with it.

 

My connector and pins for the hvac control panel connection have arrived.

 

Spoiler: So here's the burned connectors

This is a link to the toyota housing part #90980-11615

https://www.toyotapartsdeal.com/oem/toyota~housing~connector~f~90980-11615.html

There's no mention of replacement pins as well, so I chose to go another route. I went to Aliexpress and bought this:

https://www.aliexpress.com/store/pr...l?spm=2114.12010612.8148356.14.478b6db197MHvS

Spoiler: To remove the pins you first have to remove the connector housing insert

Spoiler: Use a small screwdriver to release and transfer the pins one by one

Spoiler: Make a pigtail with a new pin and 12AWG primary wire, chop off the burned pin and splice the wires

Spoiler: You will need a crimper like this. I think this one came from Fry's

Spoiler: Heat shrink over the splice, insert the pin, replace the housing insert and install your HVAC control panel