Common Problems - Carrier 40MBDQ series Owner's Manual

Common Problems

The following symptoms are not malfunctions and in most situations will not require repairs.
Problem
Unit does not turn on when pressing ON/ OFF
The unit changes from COOL mode to FAN mode
The indoor unit emits white mist
Both the indoor and outdoor units emit white mist
The indoor unit makes noises
Both the indoor unit and outdoor unit make noises
The outdoor unit makes noises
Dust is emitted from either the indoor or outdoor unit
The unit emits a bad odor
The fan of the outdoor unit does not operate
PROBLEM
Unit/System Does Not Work
Poor cooling performance
Poor heating performance
Unit Stops During Operation
* Diagnostic lights are a combination of lights that will illuminate in the display area on the unit. They are a combination of the lights you see during normal
operation.
Table 3—Common Problems
The unit has a 3-minute protection feature that prevents the unit from overloading. The unit cannot
be restarted within three minutes of being turned off.
Cooling and Heating Models: If the Operation light and PRE-DEF (Pre-heating/ Defrost) indicators
are lit up, the outdoor temperature is too cold and the unit's anti-cold wind is activated in order to
defrost the unit.
In Cooling-only Models: If the "Fan Only" indicator is lit up, the outdoor temperature is too cold and
the unit's anti-freeze protection is activated in order to defrost the unit.
The unit changes its setting to prevent frost from forming on the unit. Once the temperature
increases, the unit will start operating again.
The set temperature has been reached, at which point the unit turns off the compressor. The unit will
resume operating when the temperature fluctuates again.
In humid regions, a large temperature difference between the room's air and the conditioned air can
cause white mist.
When the unit restarts in HEAT mode after defrosting, white mist may be emitted due to moisture
generated from the defrosting process.
A squeaking sound is heard when the system is OFF or in COOL mode. The noise is also heard when
the drain pump (optional) is in operation.
A squeaking sound may occur after running the unit in HEAT mode due to expansion and contraction
of the unit's plastic parts.
A low hissing sound may occur during operation. This is normal and is caused by refrigerant gas
flowing through both the indoor and outdoor units.
A low hissing sound may be heard when the system starts, has just stopped running or is defrosting.
This noise is normal and is caused by the refrigerant gas stopping or changing direction.
The unit will make different sounds based on its current operating mode.
The unit may accumulate dust during extended periods of non-use, which will be emitted when the
unit is turned on. This can be mitigated by covering the unit during long periods of inactivity.
The unit may absorb odors from the environment (such as furniture, cooking, cigarettes, etc.) which
will be emitted during operations.
The unit's filters have become moldy and should be cleaned.
During operation, the fan speed is controlled to optimize product operation.
Table 4—Troubleshooting Tips
POSSIBLE CAUSE
• The circuit breaker has tripped or a fuse has blown.
• Power failure.
• Diagnostic lights illuminate.*
• Voltage is too low
• Remote control batteries are dead
• The unit's 3 minute protection has been activated.
• The filter is blocked with dust.
• Temperature is not set properly.
• A window or door is open.
• The outdoor unit is obstructed.
• The fan speed is too low.
• The operation mode is in Fan instead of Cool.
• Low refrigerant due to leak or long-term use of
refrigerant.
• The filter is blocked with dust.
• Temperature is set too low.
• A window or door is open.
• The outdoor unit is obstructed.
• The Off timer is not operating correctly.
• Diagnostic lights illuminate.*
Possible Causes
• Reset the circuit breaker or replace the fuse with the
specified replacement fuse.
• Restart operation when the power is restored.
• Call your service representative.
• Call your service representative.
• Replace the remote control batteries
• Wait three minutes after restarting the unit.
• Clean the air filter.
• Check the temperature and reset if necessary.
• Ensure all doors and windows are closed while
operating the unit.
• Turn the unit off, remove the obstruction and turn it back
on.
• Change the fan speed selection.
• Change the operating mode to Cool or reset the unit.
• Check for leaks, re-seal if necessary and top off refriger
ant.
• Clean the air filter.
• Check the temperature and reset if necessary.
• Ensure all doors and windows are closed while operating
the unit.
• Turn the unit off, remove the obstruction and turn it
back on.
• Restart the operating mode.
• Call your service representative.
11
SOLUTION