July 11, 2017
Machine Upkeep articles are taken from the archives of Southern Loggin’ Times.
By: Barry O’Leary, Technical Support Specialist, Caterpillar Forest Products
Now is the time to make sure the air conditioning systems in your equipment are ready for the long, hot summer. Here are tips on what to check and how to maintain the AC.
Air Filters—Clean air filters are the most important aspect of keeping AC in working order. Cab fresh air and recirculation filters are designed to provide clean air to the system and keep the cab pressurized. Clogged filters reduce airflow to the operator and reduce cab pressurization, which allows dirt to infiltrate the cab. If filters are not properly maintained, the evaporator coil will be coated with dirt, retarding cooling.
Filters should be inspected daily. Intervals for cleaning or replacing air filters depend on the severity of the application and the environment. If conditions are extremely dusty, filters might need to be cleaned/replaced daily; weekly intervals might be sufficient. In addition to inspecting filters for dirt, look through the filter toward a bright light to check for holes. Check for damaged gaskets or dented metal; toss damaged filters.
Replacing filters is preferable to cleaning them. The filter’s efficiency is reduced every time it is cleaned. However, if you choose to clean, you can remove loose dirt with compressed air. Do not exceed 100 PSI from an air nozzle that is 0.125 in. in diameter. Keep the air nozzle at least 2 in. from the filter.
The fresh air filter should be replaced at least two or three times a year, or when damaged or so caked with dirt that it cannot be cleaned. Recirculation filters are foam and can be blown out with low-pressure air and also may be gently washed with a mild detergent. After washing filters, dry with low-pressure air.
Condenser Coil—A clean condenser coil is the next most important aspect. In order for an HVAC coil to function properly, air must flow freely across the fins. Severe applications can cause the coil to become dirty quickly, requiring frequent cleaning. If the coil is not kept clean, the system has to work harder and this can shorten the life of the compressor or even cause it to fail.
Clean the coil with compressed air. You can wash with a low pressure power washer; however, this is not a good idea if the machine is going right back to work because the wet coil will collect dirt. Whichever method used; stand back a safe distance, so the pressurized air/water does not damage the fins. During normal operation and routine cleaning, it is possible for fins to bend. This could block airflow, reducing performance. Special tools are available to straighten fins. Do not use a screwdriver or knife, as they can damage the coil. Start at one side of the coil and work toward the other.
Other Checks—Blowers and fans: Make sure the remote condenser fans operate when the AC is on and that the blower fans for the cab operate on all speed settings.
Condensate drain lines: Make sure drain lines are clean and allow condensate flow. Also see that all drain valves are correctly located and not draining onto other vital components.
Compressor: Make sure dust caps are securely installed on service ports. Make sure the clutch engages when the AC switch is on and the temperature control is set to maximum cooling.
Compressor drive belt: Check for wear and damage. Is the belt loose or squealing? A dealer may be better equipped to make adjustments.
Hoses and connections: Check these on the refrigerant lines for leaks. Most systems have a green fluorescent dye, which can be seen with a black light. Make sure there are no kinks and that nothing is rubbing on hoses. Check the cleanliness of the wire connections for the compressor and make sure they are not damaged.
Evaporator coil: If there is a dust bypass around the filter, the evaporator coil could get dirty and reduce performance. A dealer may be better equipped to clean it.