John Deere 4720 Blower motor Resistor pack .75+.75- 216/22

[sbeckwith]

Found that the Blower motor Resistor pack .75+.75- 216/22 on my John Deere 4720 I use for moving round bales and feeding is bad. Trying to locate this part in the USA. Both of mine are bad and JD wants me to replace the entire blower motor when all that is needed is this resistor pack. I found it here: Resistor .75+.75- 216/22 for 12V/24V Spal 3 speeds :: Hattink Heesch - Thermo-King Parts and Carrier Parts for Transport Refrigeration but I am hoping to source is from the USA or find a direct replacement. Has anyone been down this path with solution? Thanks

For those curious, If one or both of your blower motors only run when the speed switch is set to High, these resistor packs are most likely bad. The roof has to be lifted off to get to the Blower Motor and get access to these as they are mounted onto the blower motor. It is good to have a second person help lift the roof off after removing all of the nuts that hold it on. It's a good idea to replace the sealing gasket for the roof as well once the repair is made.

 

[kennyd]

There was a thread here (or on GTT) about this, but I'm having trouble finding it now.

 

[jigs_n_fixtures]

I had the pack on one of my cars go bad. $135, dealer only part. So I opened it up to see what was inside.

What had failed was the thermal fuse. Went to Radio Shack and bought a five pack of them for just over $3. Crimped it in, and the pack was “rebuilt“ and worked fine until I loaned my mom the van to drive church ladies to a meeting.

Could never convince her that if it had been parked in the Vegas sun, you needed to run the the A/C on high with the windows rolled down, until you had cold air coming out of the vents, or it would blow the thermal fuse. But she was my mom, and I liked the church ladies. So, I didn’t mind replacing the thermal fuse a couple of times every summer.

 

[kennyd]

THis is one of the threads I was think of, but no specific info that I seem to remember seeing...still searching as time allows.

JD4720 Cab No air (heat) r coming from left side cab ports

JD must have decided that 2 blowers are better than one after mine was made. I do like the idea of 2 blowers as to maybe give better airflow. Mine does not cool that well on a very hot day. Now I wish mine had 2.

www.tractorbynet.com

 

[sbeckwith]

Replacing the thermal fuse would be quite easy - Digikey has thermal fuses - Now to figure out how to determine the correct thermal fuse

 

[5030]

Replacing the thermal fuse would be quite easy - Digikey has thermal fuses - Now to figure out how to determine the correct thermal fuse

EXACTLY. So does DigiKey. I never buy OEM, too expensive.

 

[sbeckwith]

It is a 20 amp fuse feeding the Blower motor switch - Digikey has 10 amp DC thermal fuses. I am going to make an assumption that 216 part of the number is the temperature range but am not sure what the /22 part is detailing 216/22.

Thinking my first option would be:
USW-128T Thermal Cutoff (TCO) 250 V AC 125 V DC 10 A 240°C (464°F) Axial

https://www.digikey.com/en/products/detail/us-electronics-inc/USW-128T/14123774

And my second option would be:
USW-139T Thermal Cutoff (TCO) 250 V AC 125 V DC 10 A 216°C (421°F) Axial

https://www.digikey.com/en/products/detail/us-electronics-inc/USW-139T/14123781

What to the Pro's here think... should I give it a go and if so, which one would you go with.

 

[bearthebruce]

I used to design transformers and motor controls. 216C outside the device seems to me to be way too high a temp for an external thermal cutoff. Burried deep inside the coils - might be appropriate.

I make the assumption this device is mounted on the motor housing? So if it was allowed to run the outside of the motor at over 400F, don't you think the plastics and stuff around it would be dis-colored?

As external device, 100C would be the max I would expect is acceptable. Safety of personnel would also have to come into play. At 100C someone will get burned.

All said, I have never replaced one of these and I am not suggesting I am an expert here. I just don't remember ever putting a 216C thermal cutoff outside a transformer or motor.

 

[sbeckwith]

Yea, I am thinking it may be due to the being mounted right on the motor. Not sure I like that design as the two main things that kill electrical devices is heat and vibration. I am hoping someone has at least tried doing something similar and might have some insight.

 

[sbeckwith]

Finally getting around to sharing an update to help those who may be looking for the actual blower assembly and/or the Speed Resistor.

The Blower complete with resistor pack is part #BM3908
At this time they sell for around $130

The Speed Resistor is #220-603
At this time they sell for around $30.00

You can repair the Speed Resistor pack too as I spoke of above - but for thirty bucks... it's a field repair with a buddy to help lift the top off.