The auxiliary power unit (APU) on a carrier truck provides many comforts that make life on the road more bearable for truckers. With the APU running, truck drivers can enjoy heating, air conditioning, electricity and more without having to keep the truck engine running. But when that APU stops working properly and the AC quits, it can make for some uncomfortably hot times in the truck cab.
If you find yourself suddenly without working A/C from a malfunctioning APU on your carrier truck, don’t panic. This article covers some troubleshooting tips so you can hopefully get back to trucking in cool comfort quickly. We’ll also look at some temporary solutions to try while waiting for repairs.
Diagnosing Carrier APU AC Problems
When you go to switch on the A/C and get little to no cool air blowing, there are a few key things to check before calling for service. Systematic troubleshooting can help pinpoint the cause and determine if it’s a quick fix or requires professional attention.
Check Power to the APU
The first thing to check is if the APU is actually powered on. Verify the control panel indicates the APU has electrical power. If not, check whether the APU battery needs recharging from the truck alternator or if battery cables are loose. Lack of power could indicate a tripped breaker or blown fuse too.
Ensure Refrigerant Levels Are Adequate
With the APU powered on, listen near the external APU unit to hear if the AC compressor is running. If it’s engaged but not cooling properly, low refrigerant levels could be preventing heat transfer. Recording the APU’s refrigerant pressures can help a technician determine if the system needs recharging when serviced.
Check for Leaks, Damage and Blockages
Visually inspect the extensive APU AC system tubing for signs of leaks, cracks or damage. Make sure tubing and cooling coils aren’t obstructed by debris too. Any pinhole leaks, blocked airflow or crushed piping can inhibit normal AC operation.
Consider Control and Sensor Issues
If the APU runs but the AC seems unsupported, the issue may be electrical rather than mechanical. Faulty control boards, sensors and wiring problems in the command circuitry can prevent activation of the AC compressor. This requires expert diagnostics and electronics troubleshooting.
Stopgap Measures for Staying Cool
Getting the APU AC back up and running may take Hours or days until you can have a certified truck service technician properly assess and repair your carrier auxiliary power unit AC system. In the meantime, there are some temporary techniques you can utilize to keep reasonably comfortable:
- Use a Portable Evaporative Cooler – Keeping the truck doors open for cross ventilation, position a personal evaporative cooler or “swamp cooler” by the bunk area to benefit from the natural cooling effect of water evaporation. This can lower interior temperatures slightly.
- Insulate the Cab – Appending insulation like Reflectix to the inside of truck windows can help block solar heat gain. Closing privacy curtains also limits the amount of incoming sunlight warming the cab. Silicone sealants can temporarily patch minor A/C leaks too.
- Take Advantage of Nighttime Cooling – Avoid running heating appliances at night when outside temps drop. Keep the truck well ventilated by cracking windows and doors to allow the cooler external air to exchange with interior air, lowering the overall cabin temperature.
- Use DC-Powered Fans – Small battery-powered fans can improve comfort levels by accelerating convective cooling as air moves across your skin. Rechargeable fans offer hours of operation without needing inverter power.
- Park Strategically – When possible, park the truck oriented east-west to minimize direct sun exposure through windows. Position the vehicle so prevailing winds flow across open driver or bunk windows too. Shady spots under trees help as well.
- Wear Breathable Clothing – Choose comfortable, loose-fitting cotton clothing in light colors over darker synthetics that absorb and retain body heat. Stay hydrated and avoid caffeine and alcohol which have dehydrating effects.
When to Call for APU Service
While the above measures might briefly get you by without fully functioning APU AC in the carrier truck, extended operation without repairs can risk permanent damage. Compressor components can burn out and contaminants can corrode the system. Refrigerant leaks also contribute substantially to environmental issues.
You should call for qualified truck service soon if you notice:
- Noticeable loss of cooling after initially working
- Strange smells or sounds from the APU unit
- Signs of darkened lubricant oozing from the system
- Rapid frost buildup on any AC components
- Visible damage or displaced parts impeding performance
On longer hauls, functioning auxiliary climate control systems are truly essential. Avoid unnecessary breakdowns by having your carrier APU thoroughly inspected each year prior to peak summer cooling seasons. Performing scheduled preventative maintenance also lowers the changes of disruptive AC failures at inopportune times.
Cruising Confidently Again
Coping without a working air conditioner in a carrier truck can be challenging for even short amounts of time. While the handy tips above may temporarily alleviate the situation, be sure to get any underlying APU AC system faults properly repaired by qualified service professionals as soon as reasonably possible. Stay cool out there on the roads!