In most shops, nobody pays attention to the air compressor until the day it quits working or the moisture situation becomes so bad that cars frequently need repainted. But the heart of your shop’s production lies in your air compressor. Why? For two main reasons: No. 1, compressed air is a utility. It’s the energy source for most shop equipment. Inadequate airflow or pressure interrupts work flow just as an electrical power outage would. No. 2, compressed air mixes with the product in paint-spraying operations, and air pressure, airflow and air quality are critical to product quality.

How can you ensure your air compressor runs cooler and lasts longer? Knowing how to properly maintain this vital piece of shop equipment is a good start.

Ideally, your compressor

would be located in a clean, well-ventilated room, apart from the shop, with a piped-in clean air supply. Regular maintenance includes keeping the entire unit clean because dirt acts as an insulator and causes the unit to run hotter.

For proper maintenance, assign someone to drain the main air tank daily or invest in an automatic device that opens a bottom drain for a specified period of time each day.

Daily maintenance should also include draining the moisture traps and opening the air valve on the drain legs to remove the liquid water that’s already trapped.

Temperatures inside an air compressor can exceed 450 degrees F. If you live in an area where humidity runs high – say 80 to 100 percent – you’ve got the equivalent of a tropical rain forest inside your compressor tank and your shop air lines. Add to this the microscopic oil particles that slip past the rings and you have a disaster waiting to happen. This is especially true in the paint department and why virtually every major paint company insists on air-line purification systems as a condition to participate in their warranty programs.

It’s also important to change the oil on a regular basis. Low oil in the crankcase and sticky valves can cause the pump to work harder and run hotter. So will a clogged intake filter. Simply changing the oil at regular intervals helps to keep the internal parts well lubricated.

What else should you routinely check? Keeping the cooling fins of the aftercooler or the fins that are cast into the pump clean and free of dirt and grease will make the pump run cooler. And keeping the pump itself clean will allow the cooling fins to do their job, which is dissipating heat.

If your compressor intake isn’t vented outside, it’s particularly important to take an annual look at the valves. (This would be time well spent for anyone.) Sanding dust wrecks compressor valves. Keeping the intake filter clean is easy and makes a big difference in how hard the pump has to work to produce the air.

Refrigerant dryers require little maintenance. You need to keep the coils clean of dust and dirt. Wall-mounted separators come in a variety of configurations; some have automatic drains, some require regular filter-element changes and some require renewal or replacement of the desiccant used as a final filtering medium. Many separators are suitable for general use, but in any portion of your shop where refinishing operations are performed, buy the best units you can.

Piston compressors and rotary compressors have different maintenance and service requirements. Piston compressors require relatively little preventative maintenance besides sustaining a minimal oil level, changing the oil periodically, replacing the air inlet filter and maintaining proper belt tension. Rotary compressors may require the same items as well as oil filter and air/oil separator changes.

In addition, the pistons, cylinders, rings and valves in piston compressors will wear over time, causing the compressor to deliver less air and send more lubricating oil past the rings into the air system. Without proper filtration and added filter maintenance, this will cause paint finish problems. Preventative maintenance will slow this process. Some rotary vane compressors will also experience such wear.