1GT HVAC interior fan upgrade? testing and how-to

Bunch of us have been unimpressed with the lack of airflow from our stock fans. For some strange reason I took it upon myself to try to upgrade the fan. There exists an upgrade for the 2nd gen Tundra using a brushless fan motor assembly from a Lexus. Us 1GT owners have no such bolt-in luck. Just looking at the Lexus brushless version wiring harnesses you can see that there is more going on in there than just DC Volt + and DC Volt -. No such luck easily adapting that solution to the 1GT.

Here is one of my dogs enjoying some high speed air.


The idea originally came from this thread: https://www.tundras.com/threads/do-first-gen-tundras-any-”secret”-features.162527/page-7#post-4036498

Instead of bogging down a perfectly good unrelated thread with information I'm creating this one. In this thread I will be documenting multiple measurements of the OE fan assembly and of the replacement motor to quantify if this 'upgrade' is worthwhile. Also documenting how to replace the original fan motor with the new unit.

All measurements will be taken in the same state. Engine off, temperature at center (12 o'clock position), recirculation off, face and foot vent open, all vents full open, and air speed measured at the vent to the left of the steering column furthest from the fan assembly.
Measurements that will be recorded are as follows:
OE fan housing:
-Voltage at each fan speed
-Amperage at each fan speed
-Air flow speed at vent
-Fan RPM at each fan speed

'Upgrade' motor:
-Voltage at each fan speed
-Amperage at each fan speed
-Air flow speed at vent
-Fan RPM at each fan speed

I mean, I bought an anemometer and industrial contact-less tachometer for this. Why? For science, that's why!

With these measurements we can determine if this proposed upgrade is worth the hassle and safe to use with the original wiring.

(TLDR - splicing in a brushless motor would be too complicated, involve tooling unavailable to most, and be too difficult for the average Joe. Feel free to skip to the next section.)

My off-hand comment about taking a Milwaukee M12 brushless motor and splicing it into the stock fan housing got me thinking. Everyone wants brushless. They're faster, more compact, require less maintenance, and sometimes produce more torque than brushed motors.

The downside is brushless motors are more expensive and require more than just voltage to spin. A majority of brushless motors require a micro controller to read armature position to know when to pulse the stator in the correct sequence. You could also buy a cheap-ass Hobo Freight brushless 12v drill and rob the motor and controller from that. Then you would be stuck with the crap shoot of how the micro controller controls RPM.

Trigger movement on a brushless drill does not always equal amount of voltage going to the motor. Sometimes the micro controller sees trigger depth as a signal to increase speed. Sometimes the trigger is the actual voltage input to the micro controller that correlates to higher voltage = higher motor RPM. So that means a variable voltage output from the Tundra fan speed selector switch may not be enough to actually speed up or slow down the robbed brushless drill motor.

Most older automotive applications use the blower motor resistor to limit voltage going to the brushed fan motor to control speed. Lower fan setting, lower voltage to motor. Higher fan setting, higher voltage to motor. Newer cars may use CANBUS data from the body ECM to send fan speed signal, or a mix of CANBUS and voltage to control speed. This is how newer cars can easily use brushless motors. For the 1GT we have to work with the blower motor resistor variable voltage as our fan motor speed and power input.

Even if you can overcome the controller issue most brushless drill motors have very small light weight shafts to handle high RPM. Based on measurements from car parts websites the OE fan motor shaft is about 1.5" long and 5/16" wide. Unless you have a drill press, CNC machine, lathe, or a steady hand you will have a hard time cutting and coring out the center of the OE fan shaft to fit a brushless motor shaft into it. To add to the difficulty, if your work is misaligned then you can have a noisy or stuck fan and you just wasted an afternoon, a perfectly usable drill, and a fan.

Brushed motors don't have so many limitations. More volts = more spinny. They are also cheap and offered in any number of motor and shaft sizes. This jives with the existing setup on the 1GT. So, brushless out, brushfull in.

(Those who skipped ahead can continue reading at this point.)

Found a DC motor on the jungle website with a shaft length and diameter that closely matches the OE motor. It is also a brushed motor, has a nominal voltage of 12vdc, claims to be quiet, boasts 3,500 RPM max speed, and should physically fit the location. Since we can't change the fan size to flow more air we need to change fan RPM to get more air flow to the vents and dogs.


Motor spec sheet:
https://handsontec.com/dataspecs/motor_fan/XD3420-Motor.pdf

I haven't started hacking up the OE fan or performing in depth electrical or RPM measurements. But I did start putzing around with the new air flow meter and took some initial readings.

Blue line is air speed measured in test conditions (Engine off, temperature at center (12 o'clock position), recirculation off, face and foot vent open, all vents full open, and air speed measured at the vent to the left of the steering column furthest from the fan assembly).

Red line I turned the temperature to full cold. I'm guessing when you switch to max cold it only keeps the face vents open and closes the foot vents. You can feel a slight physical resistance when moving the temp selector to this position.

Yellow line is with temp at full cold and recirculation on.

As you can see the best air speed we can hope for is when the temp is full cold on recirc.


I'll continue to update this thread as I progress.

 

Subscribed.

This will be interesting.

 

Forgot to link the motor that was purchased for this project:
https://www.amazon.com/dp/B0B221MQLC

 

I’m in for the part where you unbolt the assembly and figure out how to take the motor out.

 

I watched that video on the DC motor. 7000 hp! You may need to upgrade your hamster wheel to an all metal one.



Obviously a typo

 

@ 7k rpm I wonder if the fan cage balance will be a bigger factor.
Watched Thread

EDIT: This reminds me of a "Project Farm" episode....
"He's going to test that!"

 

Oh, it definitely will. He may still be good since car blower wheels can spin up to 3500 rpm supposedly.

 

Some say the stock Sequoia fan is more powerful.

 

Why did I read that in Jeremy Clarkson's voice? Like when he introduces the Stig.

 

Just checked. Rockauto shows Sequoia has the same p/n fan as the Tundra but uses it for front and rear.

 

Time to get cracking.

Of note, static battery voltage measured after testing is 12.31vdc. Also it seems as if the OE fan motor can be boosted by a DC to DC converter to provide full battery voltage resulting in a higher RPM. It looks like battery voltage is still throttled by the blower motor resistor even at the highest fan setting. Testing this theory is outside the scope of the current project. Feel free to do what you wish with this information. If you decide to attempt this on your own vehicle, make sure you source a DC to DC converter than can handle the amperage load.

Also of note. As far as I am aware, my truck is still using the original blower motor resistor and original blower. The numbers below are just for an apples to apples comparison between fans and in no way intended as a reference method to troubleshoot your own system.

 

I love this. Science! Fun! Do it! I'll be keeping an eye on this one!

 

Taking a break and decided to update.




As you can see from the photos the fan assembly that this truck has/had was Denso AY194000-9114 with a build date of 09-25-06. If you attempt this mod keep in mind you are working with potentially 20+ year old plastic and may be brittle.

First step is removing the fan to expose the motor. The motor shaft has a d-shaped cross section and uses a small finger pressing into a groove on the shaft to hold it in place along with a small spring clip for tension.

Remove the spring clip and push the finger out of the groove. After this only friction is holding the fan to the shaft. Use a screw driver or small pry bar and work between the fan and motor housing to pry the fan up. Work side to side a little bit at a time to lift off the fan.

Once the fan is removed from the assembly, remove the two phillips screws. This is what holds the motor in the plastic housing.

Punch a hole in the center of the plastic housing, exposing the bottom of the motor. Press the motor out of the plastic housing.




Motor is now removed and we can see the retaining washers on the bottom. Pry the washers off with a flat-head screwdriver and tap the motor shaft either with a hammer or against a solid object. The armature will then be removed.



We can now see the permanent magnets on either side of the motor housing. Tap the exterior of the motor housing with a hammer to dislodge the magnets.



Remove the top bearing from the motor housing. Use a screw driver at an angle and tap with a hammer to remove it.


With the bearing and permanent magnets removed you can insert the new motor. Secure the motor with the provided washers and nuts. I had grind the sides down to allow the washers to sit flat. Add a drop of blue Loctite to the threads.



Cut off the excess threads.


Will post further after taking a break.

 

Aaaaand when I drilled out my fan center shaft I did it cock-eyed. Fuck. Fan is a wobblin.

https://imgur.com/a/hcSPWPy

Since the OE motor shaft has a D-shaped cross section and the replacement motor is round I had to drill it out to 5/16. I have no drill press and must have drilled at a slight angle.

Ordered a new blower assembly that shows a round motor shaft. I'll reuse the fan off it to finish this project. And if this upgrade is a bust, I'll just use the replacement and be grateful for what little breeze my vents offer.

Will update after new blower assembly arrives.

 

Cool project. Good luck

 

is grabbing another blower from eBay/junkyard and dremeling a side of the new motor shaft not an option? That’s what we do for my sons RC cars occasionally.

 

I second this…. For science

 

I've considered this, yes. If the blower I ordered is the same as OE, I will grind a flat spot on the shaft.

 

Pretty sure they meant .0007 HP hahhaha.

Online calculators say it's rated for 7.3hp/hr.

 

Maybe epoxy a plastic washer to compensate for the irregularity of the opening?

Either that or correct the flaw and use a larger shaft (TWSS).

 

Forgot to mention more about comparison between the stock motor and replacement.

The stock motor is an open housing with a sintered bronze bushing on either end of the armature. Bronze is a soft material and has been used for over a century as an inexpensive bearing substitute. When taking apart my 19 year old motor there was a TON of brush material in there. Not to mention 19 years of environmental sediment mixed in.

The replacement is a completely sealed unit with ball bearings supporting the armature. Which should lead to a more efficient motor. I think if this motor were to fail it would be from buildup of brush material gumming up the works which would pop the fuse. Even that may take several years to a decade or so, depending on use.

Any power loss from having a smaller armature and permanent magnet, compared to stock motor, will be more than made up with by the efficiency using sealed ball bearings of the new motor.

I expect to see lower amperage draw and increased RPM from the new motor. There may be a louder fan noise, but it would come from it spinning faster and not necessarily from the motor. I will be able to reuse the insulated half-dome cover with the OE unit to cut down on noise.

 

https://www.reddit.com/r/AskAShittyMechanic/s/EsmaXkl7DI

 

I have a spare laying around if you want to toy with it more before hacking into a brand new one

 

Go full taofladermaus & have a few fans 3d printed. I’m sure there are better blade profiles. Especially if you wanna increase the flow with those puck filter things. Anyone remember those?

 

Cool project.

What brushless Lexus motors have you looked at? The brushless HVAC motors used by Toyota/Lexus that I am familiar with have the controller built in. This is why we are able to swap the brushless unit into our 2nd gens, which, like the 1st gen, come with a brush motor.

 

Replacement fan has D-shaped shaft too. Guess I'm grinding the new motor shaft.

 

The Lexus LX570 and Land Cruiser of the same vintage. Both show 3 pin connector. 1GT Tundra is two pin, just power and ground.

Without looking at a Lexus diagram I can assume there is a constant key switched power for the motor control/load, ground, and another input from the blower motor resistor (if it uses one) for speed setting.

Both the Lexus and Land Cruiser show only using a blower motor resistor for the rear fan control. Both show 3 pin motor for front, 2 pin for rear.

I may be muddying the waters here, but the brushless motor of an aftermarket manufacturer references PWM (pulse width modulated) signal for fan speed. So, yeah. I'd really have to look at wiring diagrams to see how feasable adapting the control side of the equation.

Other part of things would be if the Lexus fan physically fits inside the 1GT space, if the bolt pattern and diameters are the same, fan height, etc.

@Sirfive opens up a whole new possible can of worms. With access to a 3d printer someone could create a bolt-in fan with a more efficient design. Or even print a fan and base plate to make the brushless Lexus motor physically 'bolt-in'. Still have the issue of the mystery 3rd pin to contend with.

There is more than one way to get to New York, metaphorically speaking. You can fly, drive, take a train, you'll still get there. And apparently I'm walking the Appalachian Trail to more wind.

 

Confirmed. 2011 Lexus LX570 and 2011 Tundra have a PWM signal coming from what is called the 'AC AMPLIFIER ASSEMBLY". That's the third wire and that's why the 2GT can accept the brushless motor as a bolt-in. The PWM signal is what determines fan speed. Logic says the longer the pulse width the faster the fan speed.

If there is such a controller than can convert a range of 0-12vdc as input and a 0-100% PWM signal as output, add a wire for constant key switched 12vdc+, and ground you could make a Lexus brushless motor work in a 1GT. You would take the DC+ wire that goes to the stock 1GT blower and use it as the input to the signal converter.

This conjecture is all ignoring the physical limitations of the Lexus fan assembly bolting into the 1GT housing and is only about the electrical aspect of such a swap.