Replaced the alternator on my tripac, still getting an "alt" error.

mndriver

curmudgeon extraordinare
Supporter
In 2015, I was having issues with the alternator seizing on my tripac. I could use a 15/16" socket on the shaft nut and get it to rotate with a 1/2" ratchet, but once I let it sit for a weekend, fergitaboutit.

In September, 2015, I was finally able to replace the alternator with a new one. The truck sat all summer and was never used. I needed to make a new tension adjuster anyway, so I didn't worry about it.

Ran fine all fall and winter.

Come April 2016, in Houston on a 90+°F day, crank up the microwave, I toasted my brand new alternator.

Parts guy back home replaced on warranty.

Late April, toasted another alternator. Replaced it this time with a 120 amp system.

It started acting funny on me. Quit a couple times. Gave me "alt" codes. Replaced it with another 65 amp alternator. Also replaced all of my battery wires and main apu power feed wires and relocated the 75 amp maxi-fuse up where the thermo-king upgrade moved it to.

Was still getting an occasional "alt" fault.

On Monday, talked to a guy in peculiar Mo at the flyin'j. He mentioned that thermo-king had a larger pulley and a smaller pulley to slow the speed down to keep it cooler.


OK, I'll give them a call and get the skinny on that.

The guy was partially correct.

The 65 amp alternator has a 2" pulley

The 120 amp alternator has a 3" pulley to overspin the 65 amp to put out 120 amps and has a 120 amp regulator....

Good to know.

Explain the rest of this issue to the parts guy....

"Where did you get your alternator?"

Local Parts City. Why?

"You know the tripac alternator spins backwards don't you?"

I do now I am guessing from what you're about to tell me.

"Yop. The tripac spins CCW and needs a reverse fan on it to cool. Your cooking your regulators and they are doing a thermal shutdown."

Have you got any old fans around?


"Nope. But we can get a replacement fan. Let me go look"

Wait about 2 minutes.

"Yop, we have 5 in stock on the shelf. Cost is $14.78"

Great. I'll see you about 1:30 this afternoon.

The old fan and the new fan part number from the box.

The Ryobi 1/2" cordless impact is likely the BIGGEST and most used special tool I have on the truck. Talk about handy. With a 15/16" socket, all you need to change the fan/pulley for the alternator.
IMG_20160803_210232.jpg

The old and new fan side by side.
IMG_20160803_210116.jpg

Old alternator Fan still on the APU.
IMG_20160803_210206.jpg
 
Last edited:

ironpony

Professional Pot-Stirrer
Supporter
Hmmm... I have an older Tripac. Never saw that fan thingy on it - and the ThermoKing guys have never said anything about it being a problem. If you're still having ALT code failures, the wiring from the relay board to the plug on the alternator can cause that.
 

mndriver

curmudgeon extraordinare
Supporter
My next "project" will be to finagle a new intake on it. One that will quiet the intake noise on it.
 

mndriver

curmudgeon extraordinare
Supporter
Hmmm... I have an older Tripac. Never saw that fan thingy on it - and the ThermoKing guys have never said anything about it being a problem. If you're still having ALT code failures, the wiring from the relay board to the plug on the alternator can cause that.
Wires have already been replaced.

So your saying, your alternator doesn't have a cooling fan on it?
 

mndriver

curmudgeon extraordinare
Supporter
Better close up of the box for the part number.

IMG_20160807_222527.jpg

That part number get you the CCW alternator fan. That is the correct fan for the tripac apu alternator.
IMG_20160803_210139.jpg
 

BirchBarlow

I love KW 680s
In 2015, I was having issues with the alternator seizing on my tripac. I could use a 15/16" socket on the shaft nut and get it to rotate with a 1/2" ratchet, but once I let it sit for a weekend, fergitaboutit.

In September, 2015, I was finally able to replace the alternator with a new one. The truck sat all summer and was never used. I needed to make a new tension adjuster anyway, so I didn't worry about it.

Ran fine all fall and winter.

Come April 2016, in Houston on a 90+°F day, crank up the microwave, I toasted my brand new alternator.

Parts guy back home replaced on warranty.

Late April, toasted another alternator. Replaced it this time with a 120 amp system.

It started acting funny on me. Quit a couple times. Gave me "alt" codes. Replaced it with another 65 amp alternator. Also replaced all of my battery wires and main apu power feed wires and relocated the 75 amp maxi-fuse up where the thermo-king upgrade moved it to.

Was still getting an occasional "alt" fault.

On Monday, talked to a guy in peculiar Mo at the flyin'j. He mentioned that thermo-king had a larger pulley and a smaller pulley to slow the speed down to keep it cooler.


OK, I'll give them a call and get the skinny on that.

The guy was partially correct.

The 65 amp alternator has a 2" pulley

The 120 amp alternator has a 3" pulley to overspin the 65 amp to put out 120 amps and has a 120 amp regulator....

Good to know.

Explain the rest of this issue to the parts guy....

"Where did you get your alternator?"

Local Parts City. Why?

"You know the tripac alternator spins backwards don't you?"

I do now I am guessing from what you're about to tell me.

"Yop. The tripac spins CCW and needs a reverse fan on it to cool. Your cooking your regulators and they are doing a thermal shutdown."

Have you got any old fans around?


"Nope. But we can get a replacement fan. Let me go look"

Wait about 2 minutes.

"Yop, we have 5 in stock on the shelf. Cost is $14.78"

Great. I'll see you about 1:30 this afternoon.

The old fan and the new fan part number from the box.

The Ryobi 1/2" cordless impact is likely the BIGGEST and most used special tool I have on the truck. Talk about handy. With a 15/16" socket, all you need to change the fan/pulley for the alternator.
View attachment 35824

The old and new fan side by side.
View attachment 35825

Old alternator Fan still on the APU.
View attachment 35826
Did they ever make an APU that was half way quiet yet..

My last few times out some of the newer refer trailers are getting "tolerable"

That apu unit was always terible from the start they were like sleeping next to a running lawnmower and vented the exausht off the side to comeback through under and your vents and choke ya

Heck mndriver mndriver all due respect and I know you a "buisness" man

Ive only been issued 2 or 3 units with "apu" and Id still "idle" cause i can get used to that plus the exhaust smoke aint coming back up from under

I cannot tell ya how many times Ive got up and moved to another spot when one of ya "apu" people got next to me at a truckstop

I dunno have they gotten better over the years or not
 

nan

Well-Known Member
Supporter
Never heard of an alternator without a cooling fan on it.
For APUs or in general? Because my Navigator doesn't have one. F150 doesn't have one. Accord doesn't have one. F250 has one. Jeep has an electric one.
 

r3gulator3

Friendly Neighborhood Former Technician
Supporter
For APUs or in general? Because my Navigator doesn't have one. F150 doesn't have one. Accord doesn't have one. F250 has one. Jeep has an electric one.
That flat disc behind the pulley has fins on the back side that force air through the alternator windings and regulator to cool them. And your Jeep alternator doesn’t have an electric fan.
 

nan

Well-Known Member
Supporter
Alright well what looked like an electric fan shroud is apparently a backwards installed alternator with an overly fancy regulator housing. It looked like a cover to me but googling the part shows that's the back side with the pulley facing the motor. Strange.

Hard to make it out with the engine cover on.

I don't see flat disks on the others. The diesel has an obvious fan.

Here's the Navigator's old alternator. New one looks identical. Where's the flat disk?

IMG_20190623_102831.jpg
 
Top