VRV in General
Si30-408
120
Cases for Examination
1.18 Outdoor Unit of the Cooling Only Model Operates with
Heating Operation Displayed.
Applicable
Models
VRV in general
Condition
Outdoor unit started operation when operation is initiated with the heating operation displayed in
the local remote controller.
In addition, since the corresponding unit had an optionally installed hot water coil, the coil froze
and burst.
Cause
Erroneous connection of cooling / heating select circuit of remote controller (connected between
A and C instead of B and C).
The outdoor unit has a single cooling circuit basically. Therefore, even if heating operation is
displayed in the remote controller, no switching of the refrigerant circuit is made and the outdoor
unit starts cooling cycle with heating operation displayed.
(If a cooling / heating select remote controller is attached, priority is given to the outdoor unit.)
As a result, liquid refrigerant flows into the indoor side and remaining water in the hot water coil
freezes with the pump stopped.
Measure
Recovers by correcting the wiring of the cooling / heating select remote controller.
If a heating operation is displayed in the cooling only model, confirm the terminal connection
section of the cooling / heating select remote controller of the outdoor unit.
Point of
Diagnosis
1.19 High-pressure Shutdown Occurs only When the STD
Compressor Starts.
Applicable
Models
VRV in general
Condition
High-pressure rises abnormally and the high-pressure shutdown results when the STD
compressor starts during cooling operation.
(High-pressure tends to be higher even in the operation of inverter compressor only.)
Temperature of heat exchanger thermistor of outdoor unit was found being equivalent to the
outdoor temperature when data was collected by using the service checker type III.
Cause
liquid-side stop valve was not fully open.
(The staff considered it was fully open when inspected.)
Measure
Recovers by fully opening the stop valve.
Point of
Diagnosis
Check whether the detecting temperature of heat exchanger thermistor is close to the saturation
temperature being equivalent to the high-pressure.
[Be sure to check all basic items like liquid-side stop valve and electronic expansion valve.]
