Mitsubishi air conditioners are the most popular in the world ones. They are distinguished by decent quality, high reliability and low noise level. It is worth adding the troubleshooting system presented below in form of a table to the list of benefits. It helps to carry out diagnostics and repairs.
| Problems | Cause | Solitions |
|---|---|---|
| The air-conditioner does not work at all. | ||
| Has the power switch been turned off? | Has the timer been set in the “ON" position? | Is there a power failure or a blown fuse? |
| Poor cooling or heating | ||
| Have you set the thermostat at a suitable temperature? | Is the air filter clean? (Not clogged?) | Did you leave any doors or windows open? |
| Poor cooling | ||
| Is there any direct sunlight entering the room? | Is there a heat source in the room? | Are there too many people in the room? |
| Problem | Solutions |
|---|---|
| The unit does not restart immediately after you have stopped it. (RUN light is on) | Restart is blocked for 3 minutes after you have stopped the op- eration to protect the unit. The three-minute protection timer in the microcomputer auto- matically starts it up again. |
| Airflow is not blown out when starting the HEATING opera- tion. RUN light blinks slowly (1.5 sec ON, 0.5 sec OFF) | Airflow has stopped to prevent blowing out of cold air until the indoor heat exchanger has warmed up. (2 to 5 min.) (HOT KEEP program) |
| Airflow is not blown out for 5 to 15 min. or blown out not warm wind for a moment at HEATING operation. RUN light blinks slowly (1.5 sec ON, 0.5 sec OFF) | When outdoor temperature is low and humidity is high, the unit sometimes performs defrosting automatically. Please wait. Dur- ing defrosting, water or steam may escape from the outdoor unit. |
| Airflow is not blown out when starting the DRY operation. (RUN light is on) | The indoor fan may stop to prevent re-evaporation of dehumified moisture and to save energy. |
| Some steam escapes during COOL operation. | This may occur if the room's temperature and humidity are very high. It disappears as soon as the temperature and humidity decrease. |
| There is a slight smell. | Air blown out during operation may smell. This is caused by tobacco or cosmetics adhering to the unit. |
| You hear a slight gurgling sound. | This is caused by refrigerating liquid moving within the unit. |
| You hear a slight cracking sound. | This is caused by heat expansion or contraction. |
| You hear a hissing or clicking sound. | This is caused by the operation of the refrigerant control valves or electric components. |
| After a power cut, the unit does not restart even if power has been restored. | If the auto restart function is not set, the unit will not restart automatically. Use the remote control to start the operation again. |
| Remote control signals are not received. | Remote control signals may not be received if the signal receiver on the air-conditioner is exposed to direct sunlight or other bright light. If so, cut out the sunlight or reduce the other light. |
| Moisture may form on the air outlet grills. | If the unit is operated for a long time in high humidity, moisture may form on the air outlet grills and start dripping. |
| Whistling noise is heard from the outdoor unit. | The noise means that the revolution speed of the compressor is increasing or decreasing. |
| Fan will not stop immediately after unit operation was stopped. | Indoor fan : Fan will not stop after 2 hours if set to CLEAN operation. Outdoor fan : Fan will not stop about a 1 minute period in order to protect the unit. |
| RUN light stays on even though operation was stopped. | The RUN light illuminates during CLEAN operation. Run light turns off when CLEAN operation ends. |
| Problem | Display reading | Cause | Solution |
|---|---|---|---|
| Unit will not start. | Pilot lamp does not turn on even when the POWER ON/OFF button is pressed. | Main power switch is turned off. | Turn main power on. Then press the POWER ON/OFF button to turn the unit on. |
| Main power fuse has blown. | Replace the fuse. | ||
| Outdoor unit’s ground fault breaker is open. | Reset the ground fault breaker. | ||
| A power cut has occurred (see NOTE below). | Wait until power is restored, then press the POWER ON/OFF button to turn the unit on. | ||
| Unit discharges air well, but fails to cool or heat the room well. | Remote controller shows that the unit is operating. | Improper temperature setting e.g. you have selected COOL mode, but the desired temperature setting is higher than the current room temperature. | Check the set temperature on the remote controller and the adual intake air temperature. Use the COOLER and WARMER buttons to set the temperature |
| Filters are dogged. | Clean the filter and resume operation. | ||
| Outdoor unit’s intake or outlet is obstructed. | Remove the obstrudion. | ||
| A door or window has been left open. | Shut door or window. | ||
| Unit does not start immediately. | Remote controller shows that the unit is operating. | Unit is waiting three minutes before restarting. | Wait until the unit restarts automatically. The compressor may hesitate resuming because a three-minute resume prevention circuit is incorporated in the outdoor unit for protection of the compressor. |
| Unit stops soon after starting. | Remote controller check display reads “CHECK P6" or “CHECK P8”. | Indoor or outdoor unit’s intake or outlet is obstructed. | Remove obstruction and restart the unit. |
| Filters are dogged. | Remove the obstruction. Clean the filter and resume operation. |
| Problems | Cause/Solutions |
|---|---|
| Having trouble? | Here is the solution. (Unit is operating normally.) |
| Air conditioner does not heat or cool well. | ■ Clean the filter. (Airflow is reduced when the filter is dirty or clogged.) |
| ■ Check the temperature adjustment and adjust the set temperature. | |
| ■ Make sure that there is plenty of space around the outdoor unit. Is the indoor unit air intake or outlet blocked? | |
| ■ Has a door or window been left open? | |
| When heating operation starts, warm air does not blow from the indoor unit soon. | ■ Warm air does not blow until the indoor unit has sufficiently warmed up. |
| During heating mode, the air conditioner stops before the set room temperature is reached. | ■ When the outdoor temperature is low and the humidity is high, frost may form on the outdoor unit. If this occurs, the outdoor unit performs a defrosting operation. Normal operation should begin after approximately 10 minutes. |
| Airflow direction changes during operation or airflow direction cannot be set. | ■ During cooling mode, the vanes automatically move to the horizontal (down) position after 1 hour when the down (horizontal) airflow direction is selected. This is to prevent water from forming and dripping from the vanes. |
| ■ During heating mode, the vanes automatically move to the horizontal airflow direction when the airflow temperature is low or during defrosting mode. | |
| When the airflow direction is changed, the vanes always move up and down past the set position before finally stopping at the position. | ■ When the airflow direction is changed, the vanes move to the set position after detecting the base position. |
| A flowing water sound or occasional hissing sound is heard. | ■ These sounds can be heard when refrigerant is flowing in the air conditioner or when the refrigerant flow is changing. |
| A cracking or creaking sound is heard. | ■ These sounds can be heard when parts rub against each due to expansion and contraction from temperature changes. |
| The room has an unpleasant odor. | ■ The indoor unit draws in air that contains gases produced from the walls, carpeting, and furniture as well as odors trapped in clothing, and then blows this air back into the room. |
| A white mist or vapor is emitted from the indoor unit. | ■ If the indoor temperature and the humidity are high, this condition may occur when operation starts. |
| ■ During defrosting mode, cool airflow may blow down and appear like a mist. | |
| Water or vapor is emitted from the outdoor unit. | ■ During cooling mode, water may form and drip from the cool pipes and joints. |
| ■ During heating mode, water may form and drip from the heat exchanger. | |
| ■ During defrosting mode, water on the heat exchanger evaporates and water vapor may be emitted. | |
| The operation indicator does not appear in the remote controller display. | ■ Turn on the power switch. “®” will appear in the remote controller display. |
| When restarting the air conditioner soon after stopping it, it does not operate even though the ON/OFF button is pressed. | ■ Wait approximately three minutes. (Operation has stopped to protect the air conditioner.) |
| Air conditioner operates without the ON/OFF button being pressed. | ■ Is the on timer set? Press the ON/OFF button to stop operation. |
| ■ Is the air conditioner connected to a central remote controller? Consult the concerned people who control the air conditioner. | |
| ■ Does "Of appear in the remote controller display? Consult the concerned people who control the air conditioner. | |
| ■ Has the auto recovery feature from power failures been set? Press the ON/OFF button to stop operation. | |
| “PLEASE WAIT appears in the remote controller display. | ■ The initial settings are being performed. Wait approximately 3 minutes. |
| An error code appears in the remote controller display. | ■ The protection devices have operated to protect the air conditioner. |
| ■ Do not attempt to repair this equipment by yourself. Turn off the power switch immediately and consult your dealer. Be sure to provide the dealer with the model name and information that appeared in the remote controller display. | |
| Draining water or motor rotation sound is heard. | ■ When cooling operation stops, the drain pump operates and then stops. Wait approximately 3 minutes. |
| Nothing appears in the wireless remote controller display, the display is faint, or signals are not received by the indoor unit unless the remote controller is close. | ■ The batteries are low. Replace the batteries and press the Reset button. |
| ■ If nothing appears even after the batteries are replaced, make sure that the batteries are installed in the correct directions (+, -). | |
| The operation lamp near the receiver for the wireless remote controller on the indoor unit is flashing. | ■ The self diagnosis function has operated to protect the air conditioner. |
| ■ Do not attempt to repair this equipment by yourself. Turn off the power switch immediately and consult your dealer. Be sure to provide the dealer with the model name. |
| Symptom | Possible cause | Remedy |
|---|---|---|
| Both fan and compressor do not run. | Power failure. | Wait for power supply recovery. |
| Blown fuse of power source switch. | Contact your Air conditioning specialist. | |
| Excessively low power source voltage. | Ask your electric power company. | |
| Fan runs but compressor does not run. | The set temperature of thermostat is • excessively high for cooling. • excessively low for heating. | For temperature control • decrease the set temperature at cooling. • increase the set temperature at heating. |
| The room temperature is • excessively low for cooling. • excessively high for heating. | Can not be operated as it is out of temperature control range. | |
| Fan runs but stops immediately. | Air outlet and inlet are blocked. | Remove blocking matter. |
| The filter installed in the field is clogged with dust. | Clean it. | |
| Windows and doors are being opened. | Close them. | |
| Runs but without cooling/heating. | Air outlet and inlet are blocked. | Remove blocking matter. |
| The set temperature of thermostat is • excessively high for cooling. • excessively low for heating. | For temperature control, • decrease the set temperature at cooling. • increase the set temperature at heating. | |
| Insufficient refrigerant charge. | Contact your Air conditioning specialist. |