What causes Mitsubishi Mini Split PA?

Drain pump trouble. A defective drain: a clogged drain pump or a clogged drain pipe. An open circuit in the drain float switch. Poor contact at the float switch connector. Dew condensation on the float switch, either from drain water running down its lead wire or from drain water sloshing because of a clogged filter. On twin, triple or quadruple systems, a refrigerant piping connection mix-up or indoor/outdoor connecting wires miswired between units. A faulty room temperature thermistor or liquid pipe temperature thermistor reading.

How do I fix Mitsubishi Mini Split PA?

Write down the code and count the beeps or blinks. PA and P5 both show as 5 on Mitsubishi's wireless-remote table, so the wired remote or a technician's check confirms which one you have. Turn the system off. Look for water dripping from the indoor unit or wet walls or ceiling below it, and put a towel or pan down if there is. Clean the indoor air filters. Mitsubishi lists a clogged filter as one reason drain water can slosh onto the float switch. If you can reach the end of the condensate drain line outside or at a drain, check that it isn't kinked, crushed or plugged with debris. Mitsubishi says PA won't clear until the main power is reset. Turn the system off at the breaker for a few minutes, then restart it. If PA comes back, stop resetting it and call an HVAC technician, since running it again with a blocked drain can leak water into the room.

When should I call a pro for Mitsubishi Mini Split PA?

Check the drain pump and confirm water actually drains; clear any clogging in the drain pump or drain pipe. Check the float switch resistance and the float switch connector for contact failure. Check how the float switch lead wire is mounted (drain water running down the lead can wet the switch) and check for filter clogging. On twin, triple or quadruple systems, check the refrigerant piping connections and the indoor/outdoor connecting wires between units. Check the room temperature reading on the remote controller and the indoor liquid pipe temperature reading on the outdoor controller board to rule out a bad thermistor. Reset the main power after the repair; Mitsubishi says the abnormality isn't released until then. Under warranty, go through the installing contractor or a Mitsubishi Electric Diamond Contractor.

Code: PA🔧 Mitsubishi Mini Split

Mitsubishi Mini Split Error Code PA: Forced Compressor Stop, Water Leakage Abnormality (Meaning, Causes, Fixes)

Q: What does Mitsubishi Mini Split PA mean?

PA on a Mitsubishi Electric Mr. Slim mini split means "forced compressor stop (due to water leakage abnormality)": the indoor unit's drain float switch has sat in water too long, so the control shut the compressor down to keep condensate from overflowing. It shows as 5 beeps or 5 blinks of the OPERATION light, the same count as P5 (drain pump error). The usual culprits are a clogged drain pump or drain pipe, but a float switch fault or wiring problem can also cause it. Mitsubishi says the code won't clear until the main power is reset, and finding the clog or switch fault is usually a job for an HVAC technician. Mitsubishi Electric's service manual for the PKA-A12HA7/PKA-A18HA7 indoor units (OCH637) lists PA as "Forced compressor stop (due to water leakage abnormality)" in its self-diagnosis table, shown on an IR wireless remote setup as 5 beeps or 5 blinks of the OPERATION INDICATOR lamp (shared with P5, drain pump error). Its troubleshooting table says the unit has a water leakage abnormality when two conditions are both met: (a) the intake temperature minus the liquid pipe temperature reads below the manual's threshold (printed as 14°F [-10°C]) for a total of 30 minutes, and (b) the drain float switch detects water for more than 15 minutes. If the drain sensor reads not soaked, the record of (a) and (b) is cleared. Once the abnormality is detected, it isn't released until the main power is reset. Mitsubishi Electric Singapore's Mr. Slim error chart lists PA the same way, as "Forced compressor error (due to water leakage abnormality)" at 5 blinks.

Reviewed 2026-10-24 · Based on 2 manufacturer & service sources

What the code means

Mitsubishi Electric's service manual for the PKA-A12HA7/PKA-A18HA7 indoor units (OCH637) lists PA as "Forced compressor stop (due to water leakage abnormality)" in its self-diagnosis table, shown on an IR wireless remote setup as 5 beeps or 5 blinks of the OPERATION INDICATOR lamp (shared with P5, drain pump error). Its troubleshooting table says the unit has a water leakage abnormality when two conditions are both met: (a) the intake temperature minus the liquid pipe temperature reads below the manual's threshold (printed as 14°F [-10°C]) for a total of 30 minutes, and (b) the drain float switch detects water for more than 15 minutes. If the drain sensor reads not soaked, the record of (a) and (b) is cleared. Once the abnormality is detected, it isn't released until the main power is reset. Mitsubishi Electric Singapore's Mr. Slim error chart lists PA the same way, as "Forced compressor error (due to water leakage abnormality)" at 5 blinks.

Likely causes

Drain pump trouble
A defective drain: a clogged drain pump or a clogged drain pipe
An open circuit in the drain float switch
Poor contact at the float switch connector
Dew condensation on the float switch, either from drain water running down its lead wire or from drain water sloshing because of a clogged filter
On twin, triple or quadruple systems, a refrigerant piping connection mix-up or indoor/outdoor connecting wires miswired between units
A faulty room temperature thermistor or liquid pipe temperature thermistor reading

Safe DIY checks

⚠ Before you start

Unplug the appliance or switch off its breaker before opening panels.

Write down the code and count the beeps or blinks. PA and P5 both show as 5 on Mitsubishi's wireless-remote table, so the wired remote or a technician's check confirms which one you have.
Turn the system off. Look for water dripping from the indoor unit or wet walls or ceiling below it, and put a towel or pan down if there is.
Clean the indoor air filters. Mitsubishi lists a clogged filter as one reason drain water can slosh onto the float switch.
If you can reach the end of the condensate drain line outside or at a drain, check that it isn't kinked, crushed or plugged with debris.
Mitsubishi says PA won't clear until the main power is reset. Turn the system off at the breaker for a few minutes, then restart it. If PA comes back, stop resetting it and call an HVAC technician, since running it again with a blocked drain can leak water into the room.

🛠 When to call a pro

Check the drain pump and confirm water actually drains; clear any clogging in the drain pump or drain pipe.
Check the float switch resistance and the float switch connector for contact failure.
Check how the float switch lead wire is mounted (drain water running down the lead can wet the switch) and check for filter clogging.
On twin, triple or quadruple systems, check the refrigerant piping connections and the indoor/outdoor connecting wires between units.
Check the room temperature reading on the remote controller and the indoor liquid pipe temperature reading on the outdoor controller board to rule out a bad thermistor.
Reset the main power after the repair; Mitsubishi says the abnormality isn't released until then. Under warranty, go through the installing contractor or a Mitsubishi Electric Diamond Contractor.

Parts that commonly fix it

Always match the part number to your exact model.

⚙

Mini split condensate drain pump (exact part for your indoor model)

Drain pump trouble and a clogged drain pump are the first PA causes Mitsubishi lists; match the part to your indoor unit's service manual.

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⚙

Wet/dry vacuum

Can pull a clog out of the end of a condensate drain line; a clogged drain pipe is one of Mitsubishi's PA causes.

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⚙

Digital multimeter

Used to check the float switch resistance, as Mitsubishi's PA steps call for.

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Sources

Last reviewed 2026-10-24. Always confirm against the manual for your exact model number.

Mitsubishi Mini Split Error Code PA: Forced Compressor Stop, Water Leakage Abnormality (Meaning, Causes, Fixes)

What the code means

Likely causes

Safe DIY checks

🛠 When to call a pro

Parts that commonly fix it

Mini split condensate drain pump (exact part for your indoor model)

Wet/dry vacuum

Digital multimeter

Related codes

Sources