Defrost Control - Panasonic U-4LE2E5 Service Manual & Test Run Service Manual

8. Defrost Control

9. Defrost Control

(1) Type of Defrost Control
This system uses the reverse cycle defrost.
(2) Forced Conditions
Defrost does not begin again for 35 minutes of operation after defrost was once completed.
If the outdoor unit is stopped while defrosting due to protection control or another reason, then defrost control will
not start for a minimum of 10 minutes after restart occurs.
1
Even if all indoor units are stopped while defrosting, defrost control continues until it ends.
(3) Frost Detection
Frost detection does not occur for 5 minutes after operation starts.
Frost is detected when minimum heat exchanger temperature meets any one of the condition 1 - 3 below.
Condition 1: Minimum heat exchanger temperature drops below L2 line shown in the figure below and detects
Condition 2:
Condition 3: Minimum heat exchanger temperature drops below -3°C and detects for a total of 90 minutes
twice for 4 minutes without interruption while the compressor is operating.
Minimum heat exchanger temperature drops below L1 line shown in the figure below and detects
for a total of 60 minutes while the compressor is operating.
while the compressor is operating.
Minimum heat exchanger temperature °C
-25
Control Functions - Outdoor unit
15 (Defrosting operation-end temperature)
10
Ambient temperature°C
-1 L1
-3
L2
-8
-10
Frost detection area below the bold lines L1 and L2
-25.5
-27.5
1 - 24
2WAY VRF SYSTEM
Mini VRF SYSTEM
Control Functions
unit: °C