Carrier air conditioners Error codes, malfunctions and repair

The indoor unit of the air conditioner can diagnose problems and fix them at the same time (if possible). The list of faults and Carrier air conditioner error codes are contained in the table below.

During the malfunction diagnosis process, the green indicator (P) and the orange indicator (R) blink with a frequency of 0.1 seconds, indicating a fault code. The orange indicator (R) corresponds to tens in number - a malfunction code. The green indicator (P) corresponds to units in number - a malfunction code. 2 seconds elapse between the flashing orange and green indicators. The sequence is repeated at intervals of 4 seconds.

Example: DTC 13:

  • The orange indicator flashes once.
  • Both indicators are off for 2 seconds.
  • The green indicator flashes three times at intervals of 0.5 seconds.
  • Both indicators are off for 4 seconds.
  • The sequence is repeated until the fault is resolved. If the DTC is less than 10, then the orange indicator does not blink.

Code / Description

2 - Faulty room temperature sensor

3 - Malfunction of the temperature sensor of the internal heat exchanger TC

6 - Malfunction of the reversing valve of the outdoor unit

8 - Faulty fan motor in the indoor unit

9 - No power to indoor unit

11 - Drain pump malfunction or other drainage problems

12 - Error in the software of the indoor unit (incorrect addressing)

13 - Configuration error

14 - Signal loss of the central control system

15 - Malfunction of the temperature sensor of the internal heat exchanger Tcj

18 - Malfunction of the outdoor unit control unit (G-Tr short circuit protection)

20 - Error in the recognition circuit block position

21 - Faulty current sensor in the outdoor unit

22 - Malfunction of the temperature sensor of the outdoor heat exchanger

23 - Malfunction of the discharge temperature sensor

24 - Faulty outdoor unit fan

26 - Another malfunction of the outdoor unit

27 - Blocked outdoor unit compressor

28 - Inadmissible discharge temperature

29 - Malfunction of the compressor of the outdoor unit

31 - High pressure in the circuit of the outdoor unit


Non-Defective Symptoms of the Air Conditioner

Symptom 1: Air Conditioner Not Working

The air conditioner doesn't start immediately after pressing the power ON / OFF button on the remote control. If the operation indicator is on, the system is in normal condition. To prevent overloading the compressor engine, the air conditioner starts 3 minutes after the button is pressed.

If the “PRE-DEF * operation and defrost indicators are on, the heating mode is selected. When the air conditioner is turned on, the compressor doesn't start immediately (if the protection function against cold air supply is activated) due to the too low temperature of the air leaving the indoor unit.


Symptom 2: Switching to Fan Only Mode During Cooling Operation

To prevent freezing of the evaporator of the indoor unit, the system automatically switches to the 'Fan only' mode, and after a while returns to the cooling mode.

When the room temperature drops to the set value, the compressor stops, and the indoor unit automatically switches to the "Fan only" mode, and when the temperature rises, the compressor starts again. The same principle of operation is incorporated into the control system when operating in heating mode.

Symptom 3: White Fog Comes Out of the Block


Symptom 3.1: Indoor Unit: With high relative humidity and severe pollution of the inner surface of the unit operating in cooling mode, the temperature distribution in the room becomes uneven. Complete cleaning of the indoor unit is necessary.


Symptom 3.2: Indoor and Outdoor Units: When, after the defrosting operation is completed, the system switches to heating mode, the moisture generated during the defrosting process turns into steam and is removed from the system.


Symptom 4: Noise Emitted by the Air Conditioner in Cooling Mode


Symptom 4.1: Indoor Unit: When the system is in cooling mode or in a stop state, a continuous soft hissing sound is heard.


Symptom 4.2: Indoor and Outdoor Units: During the operation of the system, a continuous quiet hissing sound is heard. Sound is caused by the passage of refrigerant vapor through the indoor and outdoor units.


Symptom 4.3: Outdoor Unit: The pitch of a working air conditioner changes. A change in pitch is caused by a change in fan speed.


Symptom 5: Dust is Blown Out of the Block

When using the air conditioner for the first time after prolonged inactivity. The dust accumulated in it during the period of inactivity is blown out of the block.


Symptom 6: The Unit Emits Odors

The unit can absorb the odors of the room, furniture, tobacco smoke, etc., and then give them into the air stream.


Symptom 7: Low Fan Speed of the Outdoor Unit

During the operation of the air conditioner, the fan speed is adjusted to optimize the operation of the system.


If one of the following malfunctions occurs, stop the air conditioner, turn off the power, and contact your local service provider.

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