mypros+
Error code reference

Midea Air Conditioner Error Code AS

Open or short circuit of ambient temperature sensor (T1).

Midea codesMidea air conditioner codes

Open or short circuit of ambient temperature sensor (T1).

First step from the service manual

Check the connection between temperature sensor and PCB. If properly connected, measure the resistance value of the sensor.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

MyPros+ Max

Get the full diagnostic procedure for AS.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What AS means on a Midea air conditioner

The AS error code on a Midea air conditioner indicates a fault with the ambient temperature sensor, designated T1. This sensor is a negative temperature coefficient (NTC) thermistor mounted on the indoor unit's PCB or positioned to read the incoming air temperature. Its resistance changes predictably as temperature changes, and the control board uses this resistance value to monitor room conditions and regulate cooling or heating cycles. When the PCB detects a resistance value outside the expected range, either too high (open circuit) or too low (short circuit), it flags the AS error and may halt normal operation to prevent incorrect temperature-based decisions.

An open circuit condition occurs when there is a break in the electrical path between the sensor and the PCB, causing the board to read an abnormally high or infinite resistance. A short circuit condition is the opposite: the circuit is unintentionally completed through an unintended path, causing the board to read near-zero resistance. Both conditions produce readings the PCB cannot interpret as valid temperature data. Common culprits include a disconnected or corroded sensor connector, a damaged sensor wire, or a failed thermistor element inside the sensor itself.

Diagnosis begins at the physical connection between the T1 sensor and the PCB. If the connector is seated properly and shows no visible damage or corrosion, the next step is to disconnect the sensor and measure its resistance with a multimeter. A functioning NTC thermistor will show a resistance value consistent with the current ambient temperature. A reading of zero ohms or infinite resistance confirms the sensor has failed and must be replaced.

Source: manufacturer service documentation.

Common causes of AS

  1. 01

    Loose or disconnected sensor connector

    Wiring / connection

    The T1 sensor plugs into the PCB via a small connector that can work loose over time due to vibration or during servicing. Inspect the connector at both the sensor end and the board end and reseat it firmly.

  2. 02

    Failed NTC thermistor

    Part replacement

    The thermistor element inside the T1 sensor can fail internally, producing either an open circuit (infinite resistance) or a short circuit (near-zero resistance). Measuring resistance across the sensor terminals with a multimeter will confirm failure if the reading is clearly out of range.

  3. 03

    Damaged sensor wiring

    Part replacement

    The wire harness running from the T1 sensor to the PCB can be pinched, cut, or corroded, breaking or shorting the circuit. Visually inspect the full length of the wire for any signs of physical damage, kinking, or corrosion at the terminals.

  4. 04

    Corroded or oxidized connector terminals

    Wiring / connection

    Moisture exposure inside the indoor unit can cause the sensor connector pins to oxidize, increasing resistance at the connection point and mimicking an open circuit. Clean the terminals carefully and check if the error clears.

  5. 05

    Faulty indoor PCB

    Part replacement

    If the T1 sensor measures correctly when tested independently and the wiring and connector show no faults, the PCB itself may be failing to read the sensor signal correctly. This is the least common cause but should be considered after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about AS

What does AS mean on a Midea air_conditioner?
The AS error code on a Midea air conditioner indicates an open or short circuit fault with the ambient temperature sensor, labeled T1. This sensor measures the room air temperature, and the control board uses that data to regulate the unit's operation. When the board detects a resistance reading outside the valid range, it triggers the AS code. The unit may stop operating normally until the sensor issue is corrected.
Can I fix the AS error on my Midea air conditioner myself?
A knowledgeable DIYer or technician can start by checking that the T1 sensor connector is properly seated on the PCB, which requires removing the indoor unit's front panel. If the connection is secure, the next step is measuring the sensor's resistance with a multimeter to determine whether the sensor itself has failed. Replacing the T1 sensor is a straightforward repair if you are comfortable working with electronics and can source the correct replacement part.
Is it safe to run my Midea air conditioner while the AS error is active?
It is generally not advisable to continue operating the unit while the AS error is present. The T1 sensor provides the ambient temperature reading the control board relies on to make accurate decisions about cooling and heating cycles. Running the unit without a valid sensor signal could lead to inefficient operation, incorrect temperature regulation, or the unit cycling on and off unexpectedly.
Will resetting my Midea air conditioner clear the AS error code?
A power reset may temporarily clear the AS error code, but it will return if the underlying fault with the T1 sensor or its wiring is not resolved. The control board continuously monitors the sensor's resistance value, so any persistent open or short circuit condition will re-trigger the error. A reset is useful for confirming whether the fault is intermittent, but it is not a repair.
How much does it cost to repair the AS error on a Midea air conditioner?
If the fix is simply reseating a loose connector, there may be no parts cost at all, only a service call fee if a technician is involved, typically ranging from $50 to $150 depending on your area. If the T1 ambient temperature sensor needs to be replaced, parts and labor combined generally range from $75 to $250. In the less common scenario where a faulty PCB is responsible, repair or replacement costs can range from $150 to $400 or more.

Related Midea air conditioner codes

All Midea air conditioner codes
View all 14 Midea air conditioner codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass