Choices, choices

When investing in equipment that will keep your cab comfy while you're shut down - don't plop down serious cash before you know what you need

By Jeff Barker
contributing writer

Anyone who has been around the trucking industry for at least several years knows that idling has been a part of trucking’s heritage for decades.

In the past, it was easily justified for a few reasons. As time goes on, that is less true. Idling is actually becoming illegal in many areas. And, in practicality, it has become too expensive to idle a big engine as the cost of fuel and maintenance increases.

That doesn’t change the fact we still need power to operate various appliances and other stuff in our cab to have a comfortable environment when away from home.

That’s where purchasing a good quality auxiliary power unit or gen set is necessary these days – especially if we are thinking long term and want a system that will last a long time instead of becoming 300-plus pounds of dead weight.

But with so many different options on the market, there are some basics you need to know to make sure you’re getting the right unit to fit your power needs.

The options
Depending on your operation and where you run most of the time, you may need an APU system, or you may get by just fine with a diesel-fired bunk heater.

Diesel-fired bunk heaters
If you generally operate your truck in the northern part of the country where you don’t normally need air conditioning at night or power to run different accessories, then these units may be a wise choice. Some of them even have engine coolant heaters that can be set to turn on at a specific time, like a few hours before you want to get rolling.

Frame-mounted APUs with engine-driven A/C compressors
These are the most common systems. If installed properly, they work well with most stock sleepers. There are different installation options among different manufacturers, which include:

Stand-alone A/C and heating systems are installed with their own evaporator/heater core assembly that also uses a separate blower fan.

Pros: They are less intrusive on a truck’s existing operating system, and can be used independently of the truck’s climate control system to serve as a back-up system while on the highway if the truck’s own A/C or heating system fails.

Cons: You will lose some storage space under the bunk, and additional ducting and vents will need to be installed.

Integrated with existing A/C and heating system where the APU shares part of the truck’s own A/C and heating system to operate.
The A/C and heating system of the APU is tied in to share the truck’s evaporator, heater core and blower fan.

Pros: There is usually a cleaner, neater installation with little or no loss of storage space under the bunk, as there’s no need to install a separate evaporator/heater core assembly and install vents and duct work.

Cons: If the A/C system develops a Freon leak, there’s not another system to back it up like there is with a stand-alone type system. Also, if the truck it’s being installed on is under warranty, the integration of the aftermarket system into the truck’s electrical and A/C systems can cause warranty concerns. It’s advisable to check with the truck manufacturer before getting this type of system installed. If you tend to trade trucks often and want to move the APU, it can often take longer to uninstall and reinstall it.

All-electric under-bunk A/C and heating systems
These systems are either powered by a frame-mounted generator or a battery pack and inverter that supplies power to an A/C and heating system mounted under the bunk. They use their own blower fan and duct work.

Pros: These systems can also be set up to run on 120-volt shore power if running the APU’s engine isn’t allowed or practical. Electric heat works instantly after turned on.

Cons: Loss of storage space under the bunk. Systems powered by battery packs are often heavy, have a lower Btu rating and are generally limited to 10 hours of use before the batteries need a recharge. They are not practical for those who experience lengthy layovers and/or operate in extremely hot or cold climates.

Frame-mounted generators used with RV-style roof-top A/C units
These systems are typically used with larger custom-built sleepers that require a higher Btu rating to cool in the warmer areas of the country during the summer. These types of systems have found their way onto many trucks with flat-top and mid-roof factory sleepers in recent years as well.

Pros: Ability to run on 120-volt shore power. Higher cooling capacity and can be used with a diesel-fired bunk heater in the winter to save hours on the generator.

Cons: If installed on a factory sleeper, these require a hole to be cut into the roof that can hurt resale value. Also, not all factory sleepers are capable of supporting the weight of a roof-mount A/C unit, which is usually 150 pounds or more.

A reputable truck body shop would be able to tell you if your particular sleeper roof will be strong enough, and in many cases can cut the hole in the proper place and install reinforcement bracing, if needed, before mounting the roof-mount A/C unit for you.

Do I need a built-in generator to run my appliances?
No. For 120-volt power, you’re better off using a good quality power inverter with an APU that has a larger alternator, at least 100 amps. This way, if your APU engine won’t run for some reason you can still use the inverter to run your appliances. If you’re using a refrigerator that runs on 120 volts, this will keep you from having to run the APU constantly. Besides, adding an AC generator adds more weight. About the only time an AC generator is justified is for operating an all-electric A/C or heating system, and even so you’re still better off using an inverter for other 120-volt items.

Ask around
Once you know specifically what type of equipment you’re interested in purchasing and have done your own research to see which manufacturers produce it, then it’s time to get some answers.
Ever hear the old saying “Get your answers straight from the horse’s mouth”?

Before you approach a salesperson, it’s best to talk with people who have had their units for awhile – whether they may be company drivers or owner-operators – and be sure to ask several different users who have the unit you’re considering.

Here are examples of questions to ask:

• How long have you had your APU?
• What problems have you had with your APU, if any? What kind of problems may have been a result of improper installation?
• How hard has it been for you to get parts and/or service for maintaining and repairing your APU?
• Are maintenance items like oil, fuel, air filters and belts easy to find, like at an autoparts store?
• How easy is it to do your own maintenance on your APU?
• How well does the manufacturer stand behind their product and take care of you?
• Did you encounter any hassles getting your unit installed? In other words, did the installing dealer honor their agreement to an appointment? Who did the installation?
• Would you ever buy another APU from that particular manufacturer again? If not, why?

If you can, get to hear their units run. Remember how loud or quiet each unit you’re interested in is in comparison to others you’re considering. A unit actually mounted on a truck will tell you more about its real-world sound level than one on a manufacturer’s display at a truck show or in their show room. Most of the APUs out there today are reasonably quiet, while some others seem loud enough to wake everyone in the next county out of a dead sleep.

Narrow it down
Now here comes the hard part of it all. You just may get your hands dirty, so don’t be whining about it.

You need to look closely at the APU you’re interested in buying. If you’re not very knowledgeable in mechanics, or just want a second opinion then bring a friend with you who has good mechanical knowledge.

Mounting hardware and frame construction
Being that most frame-mounted units weigh 250 pounds or more, special consideration must be given to how this unit is mounted to the frame when the abuse of a truck environment is factored in.

Ideally, the support structure and brackets should be steel, or a very thick aluminum. Thin aluminum brackets can crack and eventually break from vibration and cause serious problems. Not good.

Wiring, relay banks and electronic control modules
The idea is to have an APU with an electrical system that will remain as trouble-free as possible many years down the road. A quality APU will have the following:

• All relay banks and electronic control modules mounted inside the cab of the truck. With the amount of moisture and vibration that is in the area where the frame-mounted engine assembly is, this will ensure they’re unaffected by those adverse conditions.
  

All wiring routed neatly and away from heat sources – like exhaust components – and all wiring harness connectors are of the sealed type. If you look closely and see any crimp-type connectors anywhere, believe me, you do not want that particular unit. Any exposed copper in an electrical system is an invitation for corrosion to form in the wiring and cause mucho problems for you down the road.

• Belts and hoses readily accessible for timely and easy replacement. While maintaining or repairing an APU won’t be as hard as working on some of those foreign cars that only a 5-year-old can get his or her hands into, it helps that everything is wide open and readily accessible. Being able to do most maintenance and some repairs yourself will save you time and that all-important dinero.

Another thing to consider is that you should never buy an APU based mostly on its eye appeal. It’s also understandable that anyone in their right mind doesn’t want to put some contraption on their truck that appears to have been assembled with an old Chevy Corvair.

The right fit
Now, we need to see how the APU you’re interested in will fit onto your truck. A truly knowledgeable salesperson will be able to answer these questions for you:

• How much frame space is needed? This is important, as it can often dictate the relocation or removal of toolboxes or steps – maybe even moving a fuel tank a few inches to get it to fit.
• If your truck has wheel-to-wheel fairings, find out how far the unit extends beyond the frame? You may need to take some measurements after you get an answer, unless the salesperson can tell you for sure their unit has been successfully installed in that particular application before.
• If considering an APU that uses an under-bunk assembly, how much room is needed in my side box under the bunk for the evaporator/blower assembly?
• When choosing a location on the truck to install the frame-mounted APU assembly, it’s advisable to choose a spot that’s away from the drive tires, which create high-spray areas. The further away from your drive tires the APU is if a blowout takes place, the less likely it will be damaged by the slinging of the rubber tread.
  

The details
Before you buy into a sales pitch and plop down some serious cash, there are a few more questions you need the salesperson to answer. After getting your answers, see how they compared with the “real-world” answers you got from current APU owners.

• Where can I get parts and service for this unit? Are there commonly used items like filters and belts that I can purchase at an auto parts store?
• How easy is it for the user to maintain this unit themselves – oil and filter changes, air and fuel filter replacement, belt replacement, etc?
• What is the standard warranty, and what is covered?
• How and where can I get a unit installed? Do you do installations by appointment and how long do you need my truck to get this done?

It’s also a good idea to ask if the cooling system of the APU’s engine can operate independently of the truck’s engine cooling system if it’s tied in with it and shut-off valves are installed. This is important, because if the APU can operate in this manner, it benefits you if your truck has a failure related to your cooling system. You will be able to isolate the cooling systems and use the APU for comfort while it keeps your truck’s batteries charged for using your lights and four-way flashers until help arrives.

Beware of any salespeople who cannot directly answer your questions, or appear to be acting a bit evasive to what you’re asking them about. This is a major investment, folks.

If the salesperson doesn’t know the answer to a particular question you have, they should ask one of their installation people to answer you directly. What this boils down to is gathering the factual information you need before committing to the purchase of an APU, even if it’s not what you were hoping to hear.

Once you have done your research and decided what unit you want, then it’s time to figure out how to pay for it and where to get it installed. While higher quality APUs may be more expensive to buy initially – you get what you pay for. They’re likely built better and probably will save you a lot of disappointment and frustration down the road.

Make your decision wisely, as you are the one who will have to live with the consequences in the long run.

Jeff Barker is an OOIDA member and a former certified diesel mechanic. He may be reached at
truckmaintenancestuff@yahoo.com .