Panasonic U-8MF2E8 Service Manual page 57

13. Other Functions
13-2. Function for Automatic Judgment of Insufficient Refrigerant Gas and Overcharge
This system includes a simple function for judging the amount of refrigerant.
13-2-1. Starting refrigerant level judgment mode
Short-circuit the CHK pin on the No. 1 outdoor for 4 seconds or longer to engage this mode.
(The LED on the outdoor unit PCB begins blinking.)
13-2-2. Conditions for amount of refrigerant judgment
After judgment mode starts, judgment occurs when all outdoor units in the system have been operating
continuously for 30 minutes or longer.
* Amount of refrigerant judgment requires that all outdoor units operate continuously for 30 minutes or longer.
This is in order to prevent incorrect adjustment of amount of refrigerant based on false detection caused by
refrigerant accumulation or recovery at stopped outdoor units, which is due to failures of functional elements.
After the judgment is displayed, repeated judgment will occur under new operating conditions if all outdoor
units continue operating. Therefore, the judgment display may change when later judgments occur.
* Judgment mode is automatically canceled after 4 hours.
13-2-3. Outdoor unit PCB LED indications in judgment mode
Judgment item
Judgment mode
Normal
Insufficient gas
Overcharge
Judgment not possible
When judgment mode is not engaged, the LED indicates the normal display (OFF), or else indicates alarms
or other information.
If the insufficient gas or overcharge judgment is not stable, then recover refrigerant a little at a time when the
overcharge display appears. End refrigerant adjustment when the normal or insufficient gas display appears.
13-2-4. Canceling judgment mode
When judgment mode is cancelled, the LED returns to the standard status display (OFF unless an alarm or
other event has occurred).
[1] Automatic cancel
Judgment mode is canceled automatically when 4 hours have passed after it was started.
[2] Forced cancel
Short-circuit the CHK pin while the judgment mode display is active in order to cancel judgment mode
<Reference>
General Guidelines for Insufficient Gas and Overcharge
Judgment in automatic judgment mode can be problematic in some cases.
Therefore, the following guidelines are provided for general judgment of the refrigerant amount.
Symptoms of insufficient gas
There is an indoor unit where the position of the electronic control valve is much higher (open
Cooling
by 300 pulses or more) than it was at start, and the difference [E3 – E1] at that indoor unit is
operation
large (15 °C or more).
There is an outdoor unit where the position of the electronic control valve is much higher
Heating
(open by 300 pulses or more) than it was at start, and the difference
operation
[Liquid temp. – Gas temp.] at that outdoor unit is large (15 °C or more).
Symptoms of overcharge
Cooling
The high-pressure sensor temperature is 57 °C or higher, and the difference
operation
[Pressure sensor temp. – Liquid temp.] at that outdoor unit is large (15 °C or more).
There is an indoor unit where the position of the electronic control valve is much higher (open
Heating
by 300 pulses or more) than it was at start, and the difference
operation
[Pressure sensor temp. – E3] at that indoor unit is large (25 °C or more).
These are only guidelines, therefore the judgment may vary depending on the installation conditions,
load characteristics, and other elements.
LED1 LED2
Blinking Blinking
OFF OFF
Blinking OFF
OFF Blinking
ON ON
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Recommended response
-
-
Charge with refrigerant a little at a time.
Recover refrigerant a little at a time.
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3WAY SYSTEM
Control Functions
1