I Reset an Atlas Copco Compressor the Wrong Way Twice (Here's the 6-Step Checklist I Use Now)

Look, I've been handling service orders for industrial air compressors for about six years now. I'm not a master technician, but I'm the guy who gets the call when a production line is down and someone needs to figure out the error code on an Atlas Copco XAS 185 before the plant manager loses his mind. In that time, I've personally made two very stupid, very expensive mistakes when doing a basic reset. Total cost? Roughly $1,200 in rushed parts, a weekend of overtime for my crew, and a lot of embarrassment. So, I built a checklist. This is for anyone who has ever stared at a flashing red light and thought, 'I'll just hit the reset button and see what happens.'

Here's the thing—most resets aren't just flipping a switch. There are six steps you need to follow to avoid tripping a secondary fault or, worse, damaging the controller. Here's the exact process I use now.

Step 1: Identify the Specific Error Code (Don't Guess)

The first time I messed up, I saw a 'High Discharge Temperature' alert on the controller. I thought, 'Okay, it overheated, let it cool down, reset it.' Simple, right? Wrong. The air compressor reset seemed to work, but the unit tripped again ten minutes later. I hadn't looked at the secondary code that indicated a failing coolant valve. I just cleared the primary alarm.

What to do: Navigate the controller menu on your Atlas Copco unit. Don't just glance at the main screen. Look for the alarm history or active fault log. Write down the exact code. On an XAS 185, this usually involves pressing the 'Menu' button and scrolling to 'Alarm List.' You're looking for numbers like 'E03' or 'A05'—not just the text description. The text is a hint; the code is the diagnosis.

Step 2: Check the Physical Kill Switch and Emergency Stops

This sounds stupid, but I've done it. I was troubleshooting a unit that wouldn't accept a reset. I spent twenty minutes checking fuses and wiring. Turns out, one of the guys on the night shift had bumped the emergency stop button on the side of the unit. It was pushed in by maybe a quarter of an inch, but it was enough to disable the start sequence. The controller was fine, the system was fine, but the physical circuit was broken.

Before you even touch the controller panel, walk around the machine. Visually inspect the main disconnect switch, the emergency stop buttons (there's usually one on the controller panel and one near the air outlet), and any pressure switches. Make sure they are all in the 'Run' or 'On' position. Pulling out a tripped E-stop is not a 'reset' in the software sense, but it's often the fix.

Step 3: The 'Dry Contact' Reset (Your Best Ally)

Most people skip this. An Atlas Copco compressor—especially the newer GA and XAS series—has a remote start/stop input, often called a 'dry contact' or 'remote signal.' Sometimes a voltage spike or a brownout can cause the controller to lock out because it sees a fault on this external circuit. A standard push-button reset on the panel won't clear this.

Here's the trick: Cycle the power to the unit completely. Don't just hit the stop button. Turn off the main disconnect switch. Wait 60 seconds. Turn it back on. This forces the controller to re-initialize and re-read the state of that dry contact. On the XAS 185, I've seen this fix a 'Remote Start Failure' alarm instantly. It's the single most overlooked step in a routine reset.

Step 4: Execute the Controller Reset (The Button You Actually Press)

Now you perform the actual software reset. On most Atlas Copco controllers (Elektronikon or similar), you press and hold the 'Reset' button for three seconds. Don't just tap it. A quick tap often only silences the alarm horn but does not clear the fault. You need to hold it until you hear a second click or see the screen flash. If you're on a gauge-style controller (older units), you usually have to press the 'Stop' button first to enter the 'Ready' state, then press 'Start' again. Trying to go from 'Alarm' to 'Run' directly will fail.

Step 5: Re-Prime the System (Oil and Air)

This is where I made mistake number two. After a fault related to a 'Low Oil Pressure' shutdown, I reset the controller. The compressor started, ran for four seconds, and shut down again with the same error. I assumed the oil pump was dead. I ordered a $600 replacement part, rushed it overnight, installed it—only to find the original pump was fine. The problem was the system had lost its prime when it shut down. The oil had drained back into the sump, and the controller didn't hold the start signal long enough for the pump to re-prime.

The fix: After resetting the controller, don't just let the compressor try to start automatically. If the unit has a manual priming pump (some larger GA models do), give it 10-15 strokes. If it's an automatic system, cycle the start command manually. Start the compressor. If it alarms out immediately on low pressure, don't panic and don't order a pump. Let it sit for 2 minutes to allow oil to settle back. Then, try the start cycle again. In most cases, the second attempt will succeed as the oil has had time to flow back into the pump inlet.

Step 6: Verify the Load/Unload Cycle

Your reset is successful. The green light is on. But don't walk away yet. Let the compressor run through one full load/unload cycle. Watch the pressure gauge. Does it build pressure to the cut-out point (usually around 110-125 psi for a standard unit)? Does it unload properly? Does it re-load when the pressure drops? I can't tell you how many times I've seen a reset work for startup, but the controller didn't properly calibrate the load solenoid, causing the unit to run continuously and over-pressure the system. That's a dangerous situation.

So glad I learned this lesson before I started handing off my checklist to the new techs. Dodged a bullet on that oil pump order, but I still wasted a weekend. Take my word for it—don't skip Step 3 or Step 5. That 60-second power cycle and the oil re-prime check are the cheapest insurance you'll get.