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Stay current with A/C maintenance and smile through the summer heat
Here it comes: the heat, the humidity, the dollars flying out of your pocket to keep your truck on the highway! Well, that last part doesn’t have to happen. You don’t want to just open a window and hope for a breeze in the hot summer months, but fixing a broken A/C can break the bank. So how do you keep your cool? As always, the answer is good maintenance practices.
Sweating the small stuff
Clean cabin filters contribute greatly to the efficient operation of the A/C system and protect the compressor from catastrophic failure. They also ensure the air a driver breathes is free from mold spores and bacteria, which can affect long-term health. Servicing these filters is a fairly easy, inexpensive maintenance procedure, yet consistently gets overlooked.
A dirty cabin filter restricts the airflow to the evaporator inside the vehicle. This causes the evaporator to freeze, which could starve the compressor of refrigerant and result in an overheated compressor and eventual failure. Operators who regularly travel through dusty, humid climates need to service their cabin filters more often — twice a year or more.
Some trucks have more than one of these filters, so it is important to consult the operator’s manual for location and servicing procedures.
The A/C system cools the air by using a fluid known as a refrigerant. A very specific amount of refrigerant is needed in the system to keep the compressor cool, and a leak could lead to a shutdown. Even a small loss can have an effect. Some drivers notice that their A/C system performs adequately most of the time, but feels a bit warmer than desired when the sun is shining. This is a classic symptom that the system has a leak and is a little low on refrigerant. Drivers shouldn’t shrug off the problem and choose to tolerate a little less comfort. Deferring maintenance in this case will likely result in damage to the compressor and eventual compressor failure.
Operating an A/C system while the refrigerant level is low is the No. 1 reason why compressors fail. It is critical to react to any A/C performance issue immediately once aware of it.
Leaks can be difficult to see even for an experienced technician, so two kinds of tools must be used when examining an A/C system for leaks. Most vehicles come from the factory with a dye solution in the system that can be detected with an ultraviolet (UV) light. If the A/C system does not contain dye, a small amount can be added. Amber glasses worn by the technician aid in the visibility of that dye.
Because some areas of the A/C system will leak an acceptable amount each year, an electronic leak detector should be used in conjunction with the UV method so a false leak can be distinguished from a normal leak. The ultraviolet method detects but does not differentiate between excessive and normal.
Many modern trucks use a blended air system, which combines heat and A/C to achieve a steady temperature. The air mix is controlled by doors in the dash, typically operated by cables or with electronics. The cable system may need to be physically adjusted to ensure the doors seal properly and that they travel the correct distance to balance the blending of air. Operators can usually recalibrate the electronically controlled doors by moving the fan controller and the temperature controller to a specified position, then holding one or two additional buttons for a few seconds. Consult your owner’s manual or service manual for specific instructions.
Air conditioning systems are absolutely necessary for drivers to stay alert and physically capable of safely handling the vehicle. Following a few basic maintenance procedures keeps your vehicle on the highway, your money in your pocket and your cool all summer long.
Homer Hogg, Technical Training Manager for TA and Petro, has worked as a truck technician for more than 30 years. He is ASE Master-certified, a Daimler Certified Trainer and a member of the Nashville Auto Diesel College Hall of Fame.