The short answer
A Fujitsu mini split blinks its lamps for two reasons: something normal, like a defrost cycle or a power blip, or a fault code. A slow blink on the OPERATION lamp in heat mode is usually defrost. OPERATION and TIMER blinking back and forth means the power was interrupted, and pressing start/stop on the remote clears it. A fault code is a count of flashes on OPERATION, then a count on TIMER, over and over. Count both, find the model number, and if it comes back after one reset, call. Here’s how to read them before you call anyone in Northern Virginia.
The three lamps
Most Fujitsu wall heads have three lamps on the front: OPERATION (green), TIMER (orange) and ECONOMY (green). In normal use they just show what’s on. When something needs attention, they blink, and the pattern tells you what kind of attention.
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Normal blinks vs a fault
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| What the lamps do | What it means | What to do |
|---|---|---|
| OPERATION blinks slowly in heat mode | Defrost | Nothing. It can take up to about 15 minutes |
| OPERATION and TIMER blink back and forth | The power was interrupted | Press start/stop on the remote |
| OPERATION and TIMER blink at the same time | Test run mode | Normal right after an install or service. If nobody is running a test, call |
| OPERATION flashes a count, then TIMER flashes a count, and it repeats | A fault code | Count both and look it up |
How to count a code
- Watch OPERATION and count its flashes.
- Then TIMER flashes. Count those.
- After a pause the whole pattern repeats. Watch it a second time to be sure.
- Write it down as two numbers, OPERATION first: 1 and 1, or 4 and 1.
Some models bring the ECONOMY lamp into the pattern too. A wired wall controller skips the blinks and shows Er with the code on its screen.
Two codes we can tell you for sure
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| OPERATION, then TIMER | What it means | What usually fixes it |
|---|---|---|
| 1 and 1 | Serial communication error: the head and the outdoor unit aren’t talking | One breaker reset. If it returns, the cable between the units or a board |
| 4 and 1 | Room temperature sensor in the head | A sensor or board repair |
Past those two, the same blink pair can mean different things on different Fujitsu models, so match yours to the chart for your model number. The model number is on a label on the side of the indoor head and on the outdoor unit. Two codes we’re sure of beat a long list that’s wrong for your unit, and on a service call the tech reads the full code from the board.
What to do when it blinks
- Rule out the normal ones first: defrost in heat mode, or the back and forth power blink.
- Count the code twice and write it down with the model number.
- Do one reset: off at the remote, off at the breaker for about 5 minutes, back on.
- If the same code comes back, call. Don’t keep resetting a fault that keeps returning.
Problems that don’t blink
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| What you see | Where to start |
|---|---|
| Water dripping from the head | Mini split leaking water |
| Cool air in heat mode, or no heat | Mini split not heating |
| Clicking, rattling or grinding | Mini split making noise |
| Ice on the outdoor unit | Heat pump covered in ice |
Brand by brand: Mitsubishi, Carrier, Daikin, LG, Samsung and MrCool, Pioneer, Gree and Senville. Every code family we’ve written up is on our error codes and warning lights page.
Book it
A mini split visit starts with our $99 diagnostic, and you get the repair price in writing before anything is opened. Call (703) 997-9757 or book a visit online and tell us the brand and the code or what you’re seeing. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Mitsubishi Electric, Carrier, Daikin, Fujitsu, LG, Samsung, MrCool, Pioneer, Gree and Senville are trademarks of their owners.
Questions people ask
Why is the green OPERATION light blinking on my Fujitsu?
In heat mode, a slow blink is usually defrost and stops within about 15 minutes. A counted pattern with the orange TIMER lamp is a fault code.
What does it mean when the OPERATION and TIMER lights blink on a Fujitsu?
Back and forth means the power was interrupted; press start/stop. Both at once means test run. A count on one, then the other, is a fault code.
What is Fujitsu error code 1 and 1?
A serial communication error: the indoor and outdoor units aren’t talking. If a breaker reset doesn’t clear it, the cable between them or a board needs a look.
How do I reset a Fujitsu mini split?
Turn it off at the remote, then at the breaker for about 5 minutes, then back on. If the same code returns, another reset won’t help. Call.
Where is the model number on a Fujitsu mini split?
On a label on the side of the indoor head and on the outdoor unit. Have it ready when you call, because blink codes vary by model.
