Overall Rating3.743.743.743.743.74
Quality3.833.833.833.833.83
Dependability3.73.73.73.73.7
Serviceability3.783.783.783.783.78
Effectiveness (AC & Heat)3.783.783.783.783.78

Willis APU

WPS Premium Auxiliary Power Unit

  • State of the art design that makes no compromises to provide maximum comfort and power.
  • Eliminates the need for all non operational idling
  • Three cylinders of silent power. As much as twice the power of competing systems.
  • Low net diesel fuel usage
  • Provides optimum comfort
  • Reduces the total hours of operation of the trucks main engine increasing its useful life.
  • Provides back up power for truck power and HVAC system.
  • Integrated cooling option available.
  • Keeps batteries charged while providing power for all creature comforts.
  • Only APU capable of additional power accessories

Key Features

  • Up to 3 tons of cooling
  • Up to 2 tons of heating available for the cab and sleeper
  • Up to 4 KW of power
  • Electronic controls with programmable features
  • 20 HP Diesel Engine
  • Additional Capacity to provide for:
    • Hydraulic Pump
    • Pneumatic Compressor
    • Additional Alternator or Generator

Premium (Willis) Advantages

  • Available with Pneumatic Compressor
  • Available with Hydraulic Pump
  • Available with Additional Alternator for DC or AC power
  • May be configured with other components

Incoming search terms:

23 Customer Reviews of “Willis APU”

Review by Dusty, August 31, 2013

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

ON MY TRUCKS I HAVE TRIED SEVERAL APU UNITS. THE WORST ONE WAS THAT DYNASYS AS IT IS OWNED AND SOLD BY *** edited for inappropriate comments***. IF YOU GET A DYNASYS ALL THEY WANT FROM YOU IS YOUR MONEY. AND IF YOU ARE A LEGAL AMERICAN THEY DON’T LIKE YOU. I HAVE TRIED TRIPAC TOO AND IT DOESN’T WORK WORTH A DARN EITHER. TRIPAC TOO AND IT WAS TERRIBLE AND WE EVEN HAD A PROHEAT AND IT WAS NOT GOOD EITHER. SO MANY ENGINE ISSUES AND ELECTRICAL ISSUES. SO THE ONLY ONE THAT IS SO SO SO GOOD AND WORKS SO SO WELL IS THE WILLIS. IT IS ABSOLUTELY POSITIVELY THE BEST MADE EVERYWHERE. INSTALL IS OUTSTANDING AND IF THERE IS ANY ISSUES WHAT SO EVER IT IS TAKEN CARE OF IMMEDIATELY. BUT THEY WORK SO SO WELL AND SO OUTSTANDING.

Review by evan, October 18, 2013

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

love my willis. over 4000 hours on it. would buy another in a heartbeat.

Review by Alexei, January 27, 2014

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Overall Rating 11111
Quality 11111
Dependability 11111
Serviceability 11111
Effectiveness (AC & Heat) 11111

Well I’ve got a story to tell about these horribly, cheaply designed pieces of junk. My dad worked for a company that had them, and he was on five or six different of their trucks, and these worthless things never worked right. Once, he almost froze to death in Wyoming because the truck froze up, and this poor excuse for an APU would barely run, and when it did, all it would do is shoot out freezing cold air. No warmth at all. Then in the summer, it wouldn’t cool worth a darn either. He told me that even the mechanics that worked on these things said they were absolutely worthless. The best we’ve ever had by far is the TriPac- go with it if you want an APU that will freeze you out in the summer and cook you in the winter. Get a TriPac- you won’t regret it!

Review by Dan, September 12, 2014

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Overall Rating 11111
Quality 11111
Dependability 11111
Serviceability 11111
Effectiveness (AC & Heat) 11111

I bought a 2006 t 2000 kenworth has a Willis apu it needs work but can’t find anyone who repairs Willis in ontario canada. Trying to get help from Willis but no one gets back to you. An apu is something I always wanted for my trucks but without repair I’m dragging around a Willis for no reason

Review by Danny, March 1, 2016

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Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

thanks to all.

Review by Jackie, March 1, 2016

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Overall Rating 22222
Quality 11111
Dependability 11111
Serviceability 22222
Effectiveness (AC & Heat) 11111

These are the best…Always start and run. Radiators leak. Heater cores leak. Sensors have issues. And smoke like crazy.

Best to wait for summer if you want heat!

Review by Brad, March 2, 2016

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I have had Willis APU’s on all of my trucks for years. All of my trucks currently have the ‘Willie’ on them. This unit is bullet proof!!! The installations were done by Willis themselves and I couldnt be more pleased. I will always have Willis APU’s on my equipment!

Review by Ronnie Goodwin, March 2, 2016

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I’ve had two different Willis APU units on two different trucks and you can’t beat the quality and service anywhere. Best investment I’ve made on my trucks.

Review by Billy Ahlum, March 4, 2016

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I have had my Willis on the same truck sense 2009 and it has been a dam good unit.I have been in 20 below North Dakota weather with a wind chill of 35 below and stayed warm but most of all the truck started the next morning, 100 plus in the Arizona sun and stayed cool in the cab. Yes it has had some issues from time to time but heck what machine doesn’t! If you can change a fan belt on your truck or car, you can work on this unit. If you have a problem with it and can’t figure it out then you call Willis. Danny the mastermind behind most of the technology in this unit can talk you through a lot of the issues and get you back running, if he is not available then talk to Clayton or Rowdy, they can also solve most issues over the phone.If you need parts call! As soon as you hang up the phone Elisha is boxing them and sending them on the next truck. They are a great bunch of people and work well together to get the job done.
I have read some of the reviews on here and I can’t figure out how they are having so much trouble. If you maintain your Willis ( service, check belts and tighten a bolt every now and then ) it will last a long time. No one can tell me that they can’t get a hold of someone at Willis, they are a very small shop and get very busy so they might have to call you back or you might have to try later, but you can and will get a hold of someone.
Wills is being improved all the time, so if you bought a used Truck and have one on it then call them,see if there is something that can help you and your Willis.
You can’t go wrong with a Willis APU!

Review by George, March 7, 2016

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

Danny and his guys are great!!! I am very happy with my Willie! It has about 4000 hours on it and I have not had a single issue. I truly belieive that if properly maintained, this unit could last forever. I highly recommmend Willis!

Review by Bob & Pam Taylor, March 13, 2016

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I have almost 6000 hours on my Willis and she’s still going strong! All APU’s keep you warm but none keep you cool in Laredo, TX on hot summer day like my Willis does. I’ve been inside the sleeper of trucks with Carriers and Thermokings and the like and they just don’t put out the BTU’s that the Willis does! More importantly, we have always been treated like valued customers anytime (day or night and weekends too) whenever we had a question or concern with our unit. Mechanical things break…that’s a given, it’s how the problems are handled that makes a company great. The owner Danny, personally gets involved in solving your problems and even works on the unit. I have and will continue to send drivers to Willis APU in Springfield, MO. to see Danny and Clayton to get the best APU on the market!!

Review by Earl shank, March 17, 2016

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

The willis team is great they now there business very well. And very resonable on there priceing. They get you in and out very fast. I would recommend the willis apu to everyone out there that is looking for a apu unit.

Review by Kip D'Amico, March 19, 2016

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I bought one of the first series of Willis APU’s, (serial #502). This was at a time when they were first catching on.
I have logged over 13,000hrs on my unit with only minimal maintenance and very few repairs. The unit is amongst the quietest I’ve ever witnessed. I’ve run it in all types of weather,..from,-15°-to 107°, and have remained comfortable in all conditions.
I would definitely recommend this unit to anyone who’s serious about saving wear and tear from idling their main engine, and also interested in savings on fuel.
If and when I need to replace my truck,.you can be assured it will be equipped with the latest version of my unit.
And my thanks goes out to the staff at Willis facility for their technical information over the years!!!…
They are always just a phone call away,and never cease to amaze me at their patients when I have a question for them!
Keep up the fantastic service folks!
Sincerely, ..Kip D’Amico
Owner/Operator KXPRESS,LLC
Higganum,CT

Review by Mark Townsend, March 21, 2016

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Overall Rating 33333
Quality 33333
Dependability 11111
Serviceability 22222
Effectiveness (AC & Heat) 22222

The 3 cyl Kubota Willis APU is only spec’d to Tier 2 so always take this into account. 2007 onward rigs, don’t plan on running these in any CARB compliant states.

On quietness of operation, it’s very good. The plus sides are that whatever your truck pushes out in A/C performance & heat so will the Willis APU! On that score, it has to be the best in the industry. The down side is that if the A/C on the Willis goes out, it can affect your truck’s A/C system. The same goes for the cooling system. I can envision on a new truck having a warranty issue if the engine defect was traced to an APU fault so another factor to take into account!

That was the good news, now some bad news –maybe.
The most troublesome side of the Willis has to be the A/C system and its electronics.

Since it is connected to the truck’s A/C system, refrigerant oil has a habit of settling inside the a/c compressor. So if your truck movement operation calls for less A/C operation in the wintertime then when you DO go for A/C the compressor will be full of oil and it will “slug” the cylinders that can cause damage!—-I have even seen the safety valve blown out the back cover on occasions resulting in ALL the refrigerant being lost. Great especially if you are in So Cal in July!

Overall if installed ok it will perform well!
Nice APU, I DO NOT remember the A/C power. Go with an inverter!

On the Espar heaters, cooking of the combustion chamber is commonplace if it is run for too short a time cycling period. For some reason Espars seem to be worse than Webastos for this problem. The Webasto has self regulating fuel metering depending upon altitude etc; whereas Espars have different metering size pumps to regulate fuel flow.

On the lower end of warranty periods, the Willis has a 2000 hour/2 year warranty. Not the worst I have seen but it definately on the lower end.

It does take a large amount of space vs other APUs on the market. 32″ of frame space and the box under the bunk of over 24″. Weight is another thing to think of. With this much required space to install, a lot of installs will go under the cab putting more weight on the steer axle. Also, will not work properly behind side farings. Has a tendency to overhead once summer hits.

If an air compressor is a must, the Willis is the only APU that offers this.

Some other things to think about:

Are you comfortable having the ign switch in the “ON” position when the APU is running on A/C? The Willis must be in this mode to have “in cab A/C” operational . Some O/O’s have a big objection to this where truck theft is concerned. I have had a few O/O friends that have rejected a Willis due to security issues as leaving a multi-million dollar load with the key in the truck is not a good option for them.

Overall a nice APU but a bit on the pricey side especially if you opt for the air compressor option. The liability of the Willis being the cause of something to go wrong with the truck engine and the intigration of the AC system made me choose a different option. With truck theft as high as it is today, I can’t see leaving my key in “Accessory” mode and going to take a shower to come back to no truck as all.

Review by Richard O Davis, March 22, 2016

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Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I purchased my Willis in 2007 (March) and I had researched for many months and then decided on the Willis for several reason . I have never regretted purchasing the Willis.

It has been very dependable and I have had very little issues with it. I had a water pump go out and a thermostat.

But the bottom line is that when I get work done I go to Springfield and have it worked on if necessary. I recently had it gone through, belts , hoses, new alternator for preventative measures. The entire staff there is very knowledgeable and honest.

I would highly recommend the Willis even if you could find and APU cheaper. The dependability is well worth the few dollars it may cost. I have nothing but praise for the Willis

Review by Danny Hamilton, April 21, 2016

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Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I’ve had my Willie for over 4 years and it’s at over 17,500 hours! It has been a blessing! Sure there’s been wear parts replaced and a few odds and ends but nothing I couldn’t fix myself! I love it, wouldn’t be caught dead without it! Thanks Danny and crew!!

Review by Kenneth Duncan, June 13, 2016

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Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

I got my Willis Apu in February when I got my 2013 pet 389
So waited till now to give my thoughts on this Apu becos any Apu
Will keep you warm but only the best will keep you cool in Phoenix
Right now it’s over 100 out here at the T&A and even higher on the assault I have it set at 68 the fan on low not high and it’s. Cool
68 degrees in my truck .
So if I was going to get more trucks I will have this Apu on all of them I am totally happy with my purchase thanks Danny and the Tech’s that installed my Willis APU

Review by Tripac Dude, July 12, 2016

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Overall Rating 11111
Quality 11111
Dependability 11111
Serviceability 11111
Effectiveness (AC & Heat) 11111

Willis is crap. My dad almost froze to death one winter because the truck froze up and that so called “apu” wouldn’t keep him warm. Plus they are obnoxiously loud, about as bad as those stinking Rigmasters. Go TriPac, you won’t regret it!

Review by Mark Samples, September 14, 2016

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Overall Rating 11111
Quality 11111
Dependability 11111
Serviceability 11111
Effectiveness (AC & Heat) 11111

Are they still making these things? I haven’t seen a Willis APU on a truck in a long time. Can’t believe that it is ranked #2 on this list. I just noticed that out of the total, 18 reviews dating all the way back to 2013, 11 of them came through in March of this year. Someone at Willis has been busy typing up a storm in March it looks like. LOL. I am leaving a 1 star rating not because I know a whole lot about Willis, but just mainly because I don’t believe that they had 11 positive reviews in the month of March. All I remember from many years ago is that Willis was big, loud and heavy. Maybe they have changed but from the looks of the pictures above, it still looks the same.

Review by Robert Taylor, September 14, 2016

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Dependability 44444
Serviceability 44444
Effectiveness (AC & Heat) 44444

Mark,
Yes they are still making them! I was at the owners place in Springfield, MO not long ago! He personally will jump in with the mechanics to do service on my APU! I LOVE MY Willis APU! It has all the power I need to run AC and microwave at the same time! BTU’s are way above the competitors like Thermoking and others! And that’s what it’s all about…BTU’s…you got to have them to keep cool in the summer in my Freightliner Columbia condo. Heat is NO problem in winter. IF you want the best one, in my opinion, after two years of research…Willis APU is it. Had mine going on 4 yrs…love it!

Review by Bill Baker, June 26, 2017

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Overall Rating 11111
Quality 11111
Dependability 11111
Serviceability 11111
Effectiveness (AC & Heat) 11111

as of today 6/26/2017 telephone has been disconnected !!!!!!!!!!

Review by KIP DAMICO, June 26, 2017

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Overall Rating 11111
Quality 44444
Dependability 44444
Serviceability 44444
Effectiveness (AC & Heat) 55555

Very disappointed,….no further contact information for parts etc????….
Not a very professional way to leave us drivers out here on the road!

Review by Truck driver 4747, June 26, 2017

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Overall Rating 55555
Quality 55555
Dependability 55555
Serviceability 55555
Effectiveness (AC & Heat) 55555

We ordered parts from the Peterbilt Store in Springfield, MO.
(417)865-5355

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