Protective Functions - Sanyo CMH1972A Technical & Service Manual

7-2. Protective Functions

The numerical values such as temperature, frequency, time and current in parentheses are an example
NOTE
of CMH3172A and the values are different from the other models.
7-2-1. Defrost Detection and Release
(1) Non-stop defrosting
Defrosting sequence
Heating operation
Frost detection
Non-stop defrosting
Releasing of defrosting
Defrost does not occur during HIGH POWER operation.
NOTE
If other stopped indoor units are started during defrost operation, they begin operating in
defrost mode.
(2) Clean defrost
If all indoor units are stopped during HEAT operation, and frost is detected at the L1 line, and the
conditions for defrost are met, then defrost operation occurs, and the unit stops after defrost is completed.
4-way valve ON
Defrost detection occurs in either of the following cases:
The temperature of the heat exchanger remains at or below
the L1 line for 35 minutes after the start of HEAT operation.
The temperature of the heat exchanger remains at or below
the L2 line for 120 minutes after the start of HEAT operation.
exchanger temperature (°F)
L2
L1
Compressor
Outdoor fan
Solenoid valve
(for hot gas bypass)
Indoor fan
Temperature of the outdoor heat exchanger is at or above the
temperature shown in the table below.
Defrost operation has continued for 12 minutes (max. length).
Temperature of releasing
Defrost operation time Less than 2 minutes
Heat exchanger
temperature for
releasing defrosting
*1 The temperature for releasing of defrosting is (68 °F) or higher when the
outdoor air temperature is less than 32 °F.
68
Outdoor heat
Outdoor air
(- 4) 0
temperature (°F)
( 21.2)
( 19.4)
(-11.2)
(-13.0)
(80 Hz) operation (4-way valve ON)
OFF
ON
OFF
2 minutes or more
No releasing 57.2 °F or higher (*1)