GU-XC157 - Sharp Air Conditioner Service Manual (repair manual). Page 4

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the indoor exchanger is excessively low (indicating by excess
refrigerant power output), or when the temperature of the outdoor
exchanger is too high (indicating excess operating pressure). In
the case of heat pump versions, during the heating cycle the
temperature of the indoor exchanger is monitored to detect
excess operating pressure levels.

– Compressor temperature conditions. To prevent operating fault

and increase unit reliability, rotary compressor speed is reduced
when the factory-set temperature limit is approached. 

– Temperature conditions of main electronic components.

Compressor frequency is reduced when a temperature which
could impair correct machine operation is reached. 

– Compressor electrical absorption levels. Compressor frequency is

reduced in the event of abnormal or excessive electrical
absorption levels. 

Constant reliable performance standards, the drastic reduction of
cut-ins and cut-outs, the elimination of overcompensating settings
and enhanced heat pump defrosting, adding up to greater ambient
comfort and energy savings, and therefore economical operation.

Compressor frequency, besides being determined by the ambient
power output requirements, can also be regulated by the following
controls:
1 Prevention of indoor exchanger freezing during cooling

applications;

2 Prevention of indoor exchanger overheating during heating

applications;

3 Maximum temperature control of the outdoor exchanger during

cooling applications;

4 Compressor maximum temperature control;
5 Maximum temperature control of the compressor power module; 
6 Compressor maximum absorbed current control.
Besides the above controls of compressor frequency, the
conditioning unit features other controls which guarantee reliable
operation and greater conditions of comfort.

1 During cooling applications, the maximum permissible

compressor frequency is reduced when a lower fan speed is
programmed. This control prevents the delivery of excessively
cold air into the room. 

2 During heating applications, fan speed is determined by the

temperature of the heat exchanger, thereby preventing the
delivery of insufficiently warm air into the room.

Given the operating requirements of the inverter, this unit should be
dimensioned according to the field of power outputs available,
within the minimum and maximum frequency limits of the
conditioner. 
When the conditioning unit is switched on, maximum power output
is automatically available to reach the required conditions rapidly,
especially in the case of particularly large heat loads. During
standard unit operation, power output is determined by ambient
conditions and therefore cannot be pre-determined; tables 1, 2, 3
and 4 show the field of power output variation according to the
external temperature over the range of available compressor
frequencies, pre-set ambient temperature and maximum internal
fan speed, during summer and winter mode applications. 
For medium and minimum speed values, see the correction factors
given in table A.
For minimum and maximum yield values and absorption, see the
tables given in Specifications section.
Operation limits:
Cooling:

max. 32 °C D.B.; min. 21 °C D.B.;

max. 43 °C D.B.; min. 21 °C D.B..

Heating:

max. 27 °C D.B.; min. 20 °C D.B.;

max. 21 °C D.B.; min. -8,5 °C D.B..

The above limits satisfy the requirements of ISO standard 5151.
Given the safety devices installed on the unit, operation outside
the above limits is possible for short periods.
When relative humidity is greater than 80%, condensate may
form on air delivery when the unit operates continuously in the
cooling or dehumidification modes. 
Table B shows refrigerant line specifications (tube diameter,

extra refrigerant charge).
Table C shows electrical connection specifications (wire section,
circuit breaker size).
Dimensional data, weights, refrigerant line connections and
technical clearances are shown in the figures below.

Two painted brackets for wall installation of the outdoor unit;
complete with nuts and bolts.

Recommended when spontaneous condensate runoff is not
possible. Comprises tank and pump unit. In the event of operation
fault, a safety device cuts in to shut down operation.