Dynasys auxiliary power unit (APU)

Do yourself a favor and stay away from this APU. Do not believe all the marketing hype that they put out years ago or even recently. Their APU’s are paper weights.

I’m not one to love idling my truck. I purchased the Dynasys APU gen 3 only to arrive at the shop to be told they didn’t have the actual gen 3 in stock. This was after I was told the shop had the unit in stock and I actually paid for the unit. 1 day before my install, I get a call from the install shop apologizing that they in fact didn’t have the unit in stock. That should have been my clue to ask for a refund and save up for a ThermoKing. But I ignored all the clues and asked the install shop what they actually had in stock. They tell me that they had a Dynasys but it didn’t have a generator in it. It also costed $2,000 more than the gen 3. So, I paid the extra $2,000.

The very night that they installed the unit, I started having problems. I couldn’t keep the unit in auto mode because it would stop working. The install shop pulled me back in the next day. They did some work and told me everything was good to go. But I still couldn’t put the unit in auto mode or it would stop working. I called Dynasys customer support and was told to just use the manual mode and the unit has a Kobota engine so they are built to last. The customer support representative told me that it’s actually better for the engine to stay in manual mode rather than auto mode because the auto mode starts and stops the engine which is bad for this unit.

Everything worked great up until I reached 4600 hours, about a year and three months after purchase. The engine will no longer start. It cranks but won’t start. I went back to the install shop which they said I needed a part that was not in stock. But they had a fix for it. The fix worked for about three days and the unit wouldn’t start again.

Since this happened in the middle of Arizona dead in the summer, I needed an APU or idle my truck. There are no shops on the West Coast and each shop listed on their website told me that they have so much issues with the Dynasys APU’s and no customer support, they have stopped working on Dynasys APU’s. Don’t take my word for it, call the dealers listed on their website. So, that left me with only 2 dealers that I know for sure still service this paper weight on my truck.

I get back to the East Coast in Florida and drop my load and head straight to the shop. There was a Hurricane IAN coming so they couldn’t take the time to repair my unit. 2 days and still no start. I left after paying for the labor with a broken APU the same as I came into the shop.

Frustrated, I left headed to the other service shop, the one that installed it in the first place. But, I decided to turn around and go back to Florida. I called Dynasys customer support and they said it needed a part. I paid the other service shop to next day air mail the part to Florida. They put the new part on and still no start.

Furious now, I called Dynasys customer support and they agreed to cover the costs of repairs once I got to install shop in Ohio. They worked on it for 2 days. Finally, the unit worked for another 2 days. But then it stopped working and still will only crank but won’t start. I called Dynasys customer support line again and they basically said there was nothing else they could do to fix the unit. Both service shops are at a lost what could be the issue.

The moral of my story is stick with an APU unit that is well known and can be serviced in any state. ThermoKing’s are expensive but they last way longer than one year and they can be serviced in any state. ThermoKing also cares about their brand. I’m out of $12,000 not including maintenance and repair costs. Dynasys reputation is so poor that I can’t even sell this unit for half the price I paid for it. I only had one offer for $1,500. Try buying a used ThermoKing for $1,500. Not going to happen. Save your money and don’t waste it on these second hand APU companies that draw you in with marketing ploys that claim they have a better product than ThermoKing. Unless you’re mechanical and know how to fix diesel engines, just stay away from the others.

 

Ehhh my new green seems to be holding up quite well so far, thought its only a week old now. And i actully have a pretty similar story about TK. Honestly all brands have issues. The main brands though do have better support in general i do agree though. With that said however i do gotta ask what kind of maintaince did you do on the unit overall? Just oil changes or keep up with things like overheads and such? And to clarify here i am NOT implying you didnt do the maintaince. I just want to know how the hell you got a unit to almost 5k hours. The one i have owned and the 3 previous on company trucks before i went O/O all #### the bed at around 2 or 3k.

 

I follow the manufacturer maintenance schedule. Full PM at every 500/1000 hour cycle. I do PM’s every day by checking oil, coolant, belts, any leaks etc. At the slightest problem, I make my way to one of the service shops.

 

I am not being a smarty here, but have you tried checking your fuses? I am not sure how many are on a dynasys, but any maxifuse or inline fuse I would check the connection to those fuses. My TK legacy apu on the truck I bought wouldn't start at first after I replaced the maxifuse. It sounded like it was whirring so slow like I had a bad battery. Added just a little oil to it, and that did the trick. Started right up with a strong whirl of the starter instead of the weak and pathetic sh** I was hearing before. My TK even sometimes will have issues and I literally open the battery box and wiggle the inline fuse and problem solved.

 

Something seems way off here...

The Gen3 is the newer model Dynasys APU, so why would it cost $2k more to get a unit ( assuming older ) without a generator already on it? Also considering all of them need a gen-head to function so why would it cost extra? That's part of the actual APU.... Makes no sense.

Another thing is, why in the world did you pay prior to actually having the unit installed? Typically it gets installed, then you pay...

Or did you finance it?

4600/hours in a little over 1 year is a lot.

I've had my Dynasys Gen 2 over 5 years and it has 8500 hours on it.

And you say "second hand APU companies" so did you buy a used unit? If so I certainly hope you didn't pay $12k for it, that's for darn sure.

 

Just a helpful tip: Kubota engines are used in literally a TON of applications and equipment. If a Kubota part fails you could get it from a Kubota dealer or probably any place that rents equipment (United, Herc, Sunbelt etc).

 

Even farm and home places have a lot of those parts. The one near where i live carries belts, hoses and a bunch of other standard maintaince parts as well as some minor repair parts like gaskets hoses and stuff like waterpumps or fuses.

 

Your assumptions are completely wrong. Dynasys has at least 4 different units. The gen 3 is the only model with a generator. All the other models do not have a generator. Also, the generator is for powering outlets within the truck. It functions as an inverter. My truck has inverters, 2 to be exact, so I really had no need for a generator. What I have a need for is to keep my batteries charged with all the electronics within my truck and trailer. My truck and trailer are not typical of most truck and trailer’s in the industry. It is a customized and modified truck and trailer such that due to security protocols I cannot disclose.

And, no, I did not finance, buy used, or go with a previous model. The model I have is the newest model for the unit that I have.

Lastly, my business is unique and we are developing an on demand service for shippers. I do not care to discuss this as it is proprietary to our business model. Thus, we do not accumulate the miles that a typical carrier does, for now. And yes, We actually paid $10,000 before install and an additional $2,000 after install. We could have waited but chose not to and this was our error.

Since this unit cannot be fixed, both service shops have tried but cannot seem to get it to work, Dynasys no longer is willing to help fix the issue, We cannot keep investing money into a problem that no one can seem to solve. So, we have begun to look for buyers. The only buyer that has said they would purchase it was a shop that sells used APU’s. After all, who wants to buy an APU that doesn’t want to start unless you’re mechanically inclined? However, their offer price is way too low for what we paid.

 

We don’t know what’s failing or causing the APU to not start. Dynasys thought it was one part, which we paid for and had installed, turns out, that’s not the issue. The last shop got it to run for 2 days and it developed the same problem, cranks but won’t start.

With my less than mechanical knowledge, I managed to get it to run by keeping the choke (I think this is what it is) open, but it overheats and just stops running again.

Just yesterday, another driver came up to me as I was trying to figure out what I’m doing and told me he thinks it the engine speed sensor. He could be right. But this is far beyond my knowledge. I’m not mechanically inclined to know if he is right or wrong. I would think that if that was the issue, both shops would have figured it out.

 

I have checked the fuses and both shops checked everything. They put it on a computer and they can’t figure out why it cranks but won’t start. I can hold the choke open and it starts and runs. But as soon as I let go of the choke, it stops. If I put a wedge in the choke, it starts and runs but then I cannot stop the engine and it overheats. Once I remove the wedge, the engine stops.