Midea Dehumidifier A5 Error Code

                    Quick Answer: Error Code A5 (also displayed as AS on some models) indicates a humidity sensor malfunction or communication failure between the sensor and control board. This is typically caused by a disconnected wiring harness, corroded sensor probe, shorted defrost thermistor, or failed humidity sensor [[1]][[4]][[19]].
                

⚡ Quick Fix / Soft Reset

Clear temporary logic glitches before opening the machine:

1 Turn the unit off using the power button on the control panel

2 Unplug the power cord directly from the wall outlet

3 Press and hold the power button for 30 seconds to drain residual power from capacitors

4 Wait for 5 full minutes to let the motherboard completely reset

5 Plug the unit back in and turn it on. If A5 returns immediately, proceed to physical troubleshooting

What Does A5 Error Mean?

🔍 Primary Cause

Humidity sensor error or communication failure between sensor and main control board [[1]][[16]]

️ Common Triggers

Shorted defrost thermistor, pinched wiring, disconnected harness, or corroded sensor probe [[19]]

Symptoms

Unit may continue running but won’t properly regulate humidity or may overfill water bucket [[19]]

Repair Cost

$20-$50 for sensor replacement vs $150+ for professional service call

🔧 Step-by-Step Troubleshooting

Tools Needed: Phillips screwdriver, flathead screwdriver, digital multimeter, needle-nose pliers

1

Inspect the Humidity Sensor Wiring Harness

How to access: Unplug the dehumidifier. Remove the screws securing the back panel. Gently pry the plastic clips along the top seam using a flathead screwdriver and lift the top housing to expose the control board.

What to check: Locate the humidity sensor harness (a small wire bundle leading to a probe near the air intake). Trace the wire from the control board to the sensor. Disconnect and reconnect the plug at the board to ensure the pins are seated tightly. Look for any pinched, frayed, or chewed wires [[19]].

2

Test the Humidity Sensor (Thermistor)

How to test: Disconnect the sensor plug from the main control board. Set your multimeter to the Ohms (Ω) or resistance setting. Touch the metal probes to the two pins inside the sensor harness plug.

                            What to look for: At normal room temperature (around 70°F/21°C), a working Midea sensor should read between 10kΩ and 15kΩ. If your multimeter reads “OL” (open loop/infinity) or “0” (shorted), the thermistor is dead and must be replaced [[4]][[6]].
                        

3

Check for Defrost Thermistor Issues

The A5 error is often caused by a shorted defrost thermistor or pinched wire going to the thermistor [[19]].

What to check: Locate the defrost thermistor (usually attached to the evaporator coil). Inspect the wiring for any signs of being pinched or damaged. Test resistance – it should show consistent readings. Replace if shorted or showing infinite resistance.

4

Inspect the Main Control Board

If the sensor tests within the correct resistance range, the issue lies on the board.

What to check: Visually inspect the control board where the sensor harness plugs in. Look for burnt traces, bulging capacitors, or corroded solder joints around the sensor pins. Check the main relay for scorch marks. If the board shows physical damage, it cannot process the sensor data and will trigger A5.

🛒 Parts Replacement

If your multimeter test in Step 2 fails, you need to order a replacement Humidity Sensor Harness (often sold as a humidity sensor probe assembly). Search for your exact model number or use the OEM part number listed in your manual.

💡 Alternative Solution

If the exact OEM harness is discontinued or on backorder, you can bypass the dealer markup. Purchase a generic 10k Ohm or 15k Ohm NTC thermistor probe with a matching 2-pin JST connector from Amazon or AliExpress. Ensure the resistance rating and physical probe length match your original part. Simply plug the generic harness into the existing board connector and route the probe to the original mounting location [[4]][[6]].

Plug-and-Play Replacement

Most replacement sensors are plug-and-play with no soldering or programming required. Simply disconnect the old sensor harness and plug in the new one. No technical expertise needed beyond basic screwdriver skills [[4]][[6]].

⚠️

Repair vs Replace

Be honest with yourself about the economics of the repair before spending more money.

If your troubleshooting in Step 4 reveals a fried main control board (burnt traces or a failed relay) and the unit is out of warranty, buy a new dehumidifier. A replacement control board costs between $80 and $120; combined with your time and effort, it approaches the cost of a brand-new 50-pint unit.

If you notice thick ice buildup on the evaporator coils, or the unit blows room-temperature air while the compressor hums loudly, you have a sealed system refrigerant leak. Do not attempt to repair a refrigerant leak yourself. It requires EPA certification and expensive recovery equipment. In this scenario, recycle the broken unit and invest in a new, energy-efficient model.

                             Good News: The A5 error is typically a simple sensor issue that costs $20-$50 to fix. This is one of the most economical dehumidifier repairs you can do yourself!
                        

Important Decision

🛡️ Prevention Tips

                    Clean air filters monthly to prevent sensor contamination
Keep the unit in a clean environment – dust and debris can corrode sensor connections
Check wiring annually for signs of wear or rodent damage
Ensure proper ventilation around the unit to prevent overheating
Use a surge protector to protect the control board from power spikes

                