38GL_M…G / 38YY(S)_M…G
GB - 19
E N G L I S H
Unit maintenance and troubleshooting
Unit maintenance
The following maintenance operations must be carried out by
qualified personnel.
Cleaning the coil
When necessary, proceed as follows for more careful cleaning of
the coil:
Switch the mains supply OFF.
Remove unit top cover by losening holding screws and lifting the
cover.
Carefully clean the coil with a vacuum cleaner from inside to
outside.
With the same vacuum cleaner, dust the inside of the fan
compartment and the fan blades. Avoid any damage to the blades
which may cause future vibrations and noise.
Replace the unit cover and tighten the screws.
If the unit is started for the first time after a long period
during which it has been disconnected from the mains power
supply (for heat pump units only).
Energize the system by pressing the main switch, but do not start
the system (the remote controller must be in the OFF position).
Do not de-energize the unit during the operating season.
Troubleshooting
Before starting troubleshooting check the correct operation
of all fuses installed on the electronic cards (if any).
Compressor and fan of the outdoor unit do not start:
• Unit is not energized; check the mains power connections.
• Main switch OFF; check and put to the ON position.
• Main switch fuses have blown; replace.
• Wait for 3 minutes; compressor cycling protection is on.
• Accessory pressure switch open; check and eliminate cause.
• Mains voltage too low.
• Electrical connections loose or wrong; check and repair.
Compressor will not start, but outdoor fan is running:
• Electrical connections of compressor loose or wrong; check and
repair.
• Compressor burnt out, seized or protection device on; check for
the cause and replace compressor if necessary.
• Faulty run capacitor for the single-phase models; replace it.
Compressor starts, but stops due to its overtemperature
protection (other than stops caused by the normal operation
of the thermostat):
• Wrong refrigerant charge (excessive or low) or air or other non
condensable gases in the circuit; drain refrigerant (see note 1),
evacuate and recharge.
• Mains voltage wrong (too high or too low).
• Condenser coil obstructed; remove obstructions.
• Outdoor fan off; check cause and repair.
• Run capacitor faulty; check and replace.
• Refrigerant circuit clogged; check and remove obstructions.
• Faulty reversing valve; replace it.
• Expansion device clogged or covered with ice; drain refrigerant
(see note 1), evacuate and recharge.
Compressor runs continuously:
• Unit selected too small for actual air conditioning needs.
• Indoor temperature selection too low (cooling) or too high (heat
pump heating); check temperature selection.
• Refrigerant charge low; check and add refrigerant.
• Condenser fan faulty; replace.
• Air or other non condensable gases in the circuit; drain
refrigerant (see note 1), evacuate and recharge.
• Obstructions at air intake or dirty indoor unit filters; remove
obstruction or clean filter.
Ice on the outdoor coil (heat pump heating):
• Outdoor fan is off; check for cause and repair.
• Wrong electrical connection between indoor and outdoor units;
check and repair the electric connections.
• Check the correct positioning and connection of the outdoor coil
sensors.
Discharge pressure too high:
• Outdoor coil dirty or obstructed; clean or remove obstructions.
• Condenser fan faulty; replace.
• Refrigerant charge too high; drain some refrigerant (see note 1).
• Air or other non-condensable gases in the circuit; drain
refrigerant (see note 1), evacuate and recharge.
Discharge pressure too low:
• Refrigerant charge too low; add refrigerant.
• Outdoor coil dirty or obstructed; clean or remove obstructions.
• Indoor unit air filter dirty; clean filter.
Suction pressure too high:
• Refrigerant charge too high; drain some refrigerant (see note 1).
• Internal high pressure relief valve open; check for cause and
repair.
Suction pressure too low:
• Refrigerant charge too low; add refrigerant.
• Evaporator coil covered with ice; see the following points.
• Air circulation on the evaporator unit not sufficient; check for the
cause and repair.
• Expansion device or suction line clogged: check and repair.
• Outdoor unit fan does not stop during defrosting (heat pump
heating); check the connections.
Outdoor fan motor runs always at low speed:
• The cable is not connected to the card; check connections
between the temperature sensor and the card.
• Faulty temperature sensor; replace the sensor.
• Faulty electronic card; replace it.
Outdoor fan motor runs always at high speed:
• Short-circuited temperature sensor; replace the sensor.
• Faulty electronic card; replace it.
Outdoor fan does off or starts and stops due to its
overtemperature protection:
• Faulty fan motor capacitor; replace it.
• Electrical connections to the fan motor are loose; check and
tighten connections.
• Fan motor burnt-out; replace it.
• Fan motor bearings seized; check for cause and repair.
• Expansion device clogged or covered with ice; drain refrigerant
(see note 1), evacuate and recharge.
Note 1:
Do not release refrigerant to the atmosphere; use
refrigerant recovery equipment.
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