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ESIE15-08B
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Part 2. Troubleshooting
2. Error code based troubleshooting
19/07/16
Page 41
Daikin Altherma Monobloc CA
2.49. “UF-00” – Communication error between hydro PCB A1P and outdoor main
PCB or gas shortage
2.50. “U0” – Refrigerant shortage
Trigger
Effect
Reset
When the interunit wiring between indoor
and outdoor unit is incorrect or, when for
20 minutes during compressor operation:
A: R2T - R1T < 4°C, and
B: R2T - Te (or Tc during heating opera-
tion) > 14°C (24°C during heating opera-
tion)
Unit stops operating.
Auto-reset when problem is solved.
Possible cause
Check
Corrective action
Faulty wiring between indoor and outdoor
unit.
Check wiring between indoor and outdoor
unit (refer to wiring diagram).
Correct wiring.
Refrigerant shortage (incorrect charge /
leakage).
Check for refrigerant shortage (see
page 106).
Perform leak test.
If required, repair the leak and charge the
correct amount of refrigerant.
Refrigerant circuit is clogged.
Check for possible blockage (blockages
can be checked by measuring the refriger-
ant/pipe temperature. Sudden drop in
temperature could indicate a blockage
(remark: this is not valid for the expansion
valve)).
Replace the blocked part.
Trigger
Effect
Reset
1. Outdoor main PCB detects maximum
opening expansion valve and discharge
superheat > 50°C for 5 minutes.
2. 4 times a secondary current drop for 5
minutes (unit goes thermo off after
every drop).
Unit will stop operating.
Manual reset via user interface.
Possible cause
Check
Corrective action
Refrigerant shortage (incorrect charge /
leakage).
Check for refrigerant shortage (see
page 106).
Perform leak test.
If required repair the leak and charge the
correct amount of refrigerant.
Refrigerant circuit is clogged.
Check for possible blockage (blockages
can be checked by measuring the refriger-
ant/pipe temperature. Sudden drop in
temperature could indicate a blockage
(remark: this is not valid for the expansion
valve)).
Replace the blocked part.
Faulty expansion valve.
Check expansion valve (see page 97).
Replace expansion valve or outdoor main
PCB when required (see page 119).
Faulty pressure sensor.
Check pressure sensor (see page 94).
Replace the pressure sensor when
required (see page 130).
Faulty outdoor main PCB.
Check if the alive led is blinking in regular
intervals.
Check if the correct spare part is installed.
Check if the outdoor main PCB receives
power.
Adjust the power to the outdoor main
PCB.
Replace outdoor main PCB when alive led
is not blinking in regular intervals (see
page 119).