Atlas Copco GA Screw Compressor Repairs: Oil Pressure Sensors, Air Filter Direction, and Why OEM Beats Cheap Parts

I'm a service coordinator at an industrial equipment company. In my role coordinating emergency repairs for Atlas Copco GA screw compressors, I've handled 300+ rush orders in 8 years, including same-day turnarounds for food plants, auto part suppliers, and hospitals that couldn't afford a minute of downtime. This article is a direct comparison between two ways to handle those repairs: the quick, cheap fix and the right part.

Why compare? Because when an Atlas Copco GA screw compressor goes offline, every hour is money. The decision that matters most isn't "can we get a part fast?"—it's "which part should we get?"

The decision that changed my mind: March 2023

I didn't fully understand the gap between OEM and generic until a $40 oil pressure sensor cost a client $7,000 in lost production. The compressor kept shutting down with a low-oil-pressure alarm. A generic sensor was installed to get through the week. It lasted three days. The compressor shut down again, this time with a damaged drive because the actual oil pressure had dropped and the generic sensor never reported it.

That was the trigger event. After that, we implemented a 48-hour buffer policy for any Atlas Copco GA screw compressor repair involving a safety-related part.

Oil pressure sensor: OEM vs generic on a GA screw compressor

Let's compare the most common emergency repair I see: the oil pressure sensor.

Reliability. The OEM Atlas Copco sensor is calibrated to the exact range the GA controller expects. A generic sensor might work in the right voltage range, but "might" isn't a service plan. In October 2024, a food plant called at 2 pm with an oil pressure sensor fault on a GA 45. The local distributor had the OEM sensor in stock for $185. The plant manager found a generic one at $70 and asked me to make it work.

I told him the truth: I'd already watched a generic sensor read 4 bar when the real pressure was 3.2. That error margin is fine for a tire. It's not fine for an Atlas Copco GA screw compressor where the controller uses that reading to protect the airend.

Timing. The OEM sensor arrived by 9 the next morning. The generic would have arrived at 4 pm that day. The customer chose OEM, paid the rush fee, and the compressor was running by 10:30. The line lost one afternoon instead of two days. Even after approving that $185, I kept second-guessing: what if the generic worked fine and we'd wasted $115? Then the OEM sensor gave rock-stable readings at all four data points in the start-up test. I stopped worrying.

Which way does air filter go? A question from leaf blowers to GA compressors

The phrase "which way does air filter go?" gets typed by homeowners with a Ryobi leaf blower. It also gets typed, unfortunately, by maintenance techs holding a new filter for an Atlas Copco GA screw compressor. The same confusion shows up in both places, but the consequences are different.

On a Ryobi leaf blower, a backwards filter chokes the engine. On a GA 110 compressor, a backwards filter allows unfiltered air to bypass the element and travel straight into the compression chamber. That's how a $120 filter can become a $4,500 airend repair.

So which way does it go?

• If the filter has an arrow, point it in the direction of airflow. On a GA compressor, that's toward the compressor element/inlet valve.
• If there's no arrow, look at the pleats. The rigid mesh side is the dirty-air side, and the soft/open inner side faces the clean-air outlet.
• If you still have the old filter, install the new one in the same orientation as the dirty side of the old one.

In Q3 2024, we caught a backwards filter 15 minutes before startup on a rebuilt GA 110. So glad I double-checked. One click of the start button would have pulled dirty air into a brand-new airend. We dodged a bullet because the part number on the filter box told us which side was supposed to face out.

Atlas Copco industrial assembly solutions: the system matters more than the part

Here's the dimension most people miss. If your plant uses Atlas Copco industrial assembly solutions—cordless tightening tools, DC controllers, quality assurance systems—the compressor is part of that system, not a standalone machine. Those tools are designed around specific air pressure and air quality envelopes. A pressure drop from a clogged filter or an inaccurate sensor can change a calibrated tightening result without any visible warning.

Think of it as A vs B: A is a compressor that runs. B is a compressor that runs within the parameters the rest of the line expects. The second one is what Atlas Copco industrial assembly solutions are built for. The cheapest air filter might still catch particles, but if it creates a pressure differential that makes a DC tool alarm, the savings disappear fast.

According to ISO 8573-1:2010, compressed air purity classes define acceptable particle and moisture levels for specific applications. Industrial assembly tools often require a class that a neglected filter won't provide. That's the standard we use when we quote an emergency repair.

So when do you buy the OEM part? Here's my honest answer

Not every aftermarket part is garbage. I've used aftermarket air filters on non-critical blow-off applications without problems. But for anything that keeps a GA screw compressor running safely—oil pressure sensors, separator cartridges, inlet valves—I default to the Atlas Copco part.

Why? Calculate total cost, not sticker price.

Let's say the OEM oil pressure sensor costs $185 and the generic costs $70. Average labor to install and test a sensor on a GA 45 is about $220 if you hire a tech. If the generic fails in three months, you pay $70 + $220 again, plus the production downtime on top. The OEM sensor has a service life measured in years. Same math applies to filters: a $40 filter that lets dust through the airend costs more than any premium filter.

My rule after 8 years and 300+ rush orders:

• Buy OEM for safety, oil pressure, and anything that protects the airend.
• Aftermarket might be acceptable for external items like a fan guard or a vibration isolator.
• If a client insists on a generic for a critical sensor, I document the risk in writing and give my recommendation first.

Bottom line? The best repair is the one that doesn't come back. On an Atlas Copco GA screw compressor, that usually means paying for the part that was designed for the machine. And if you're here with a Ryobi leaf blower? Same answer for the filter question: point the arrow with the airflow. On an Atlas Copco GA, point it toward the airend.