Defrost Control - Daikin Sky Air R-407C Service Manual

Overview of the heating mode functions
3.2

Defrost Control

1
Applicable units
Purpose
2
Starting conditions:
RYP71-250B
3
4
5
Heating integral
capacity
2–38
RY35-45E(A)Z7V1
RYP71-250B
The purpose of the defrost control is to prevent frost on the outdoor heat exchanger coil. This frost
forms when the unit is in heating position.
The defrosting starts when either condition 1 or 2 has been realized.
Condition 1
The compressor has been running for a total of 25 min since the start of heating or since the end
of the previous defrosting.
Outdoor heat exchanger temp. ≤ -3˚C, and
Outdoor heat exchanger temp. ≤ 0.4 x Ta - 5˚C
-15
Compressor ON ≥ 5 min continuously, and
integral heating capacity diminishes (see
further in this section), or
Ta > -5˚C for 3 h accumulated
(if DS1-2 is ON, 40 min;
if DS2-1 is ON, 24 h), or
Ta ≤ -5˚C for 6 h accumulated
Outdoor fan is ON (not in overload control)
The integral heating capacity is calculated by using the indoor unit data (R2T - R1T) divided by the
compressor running time.
Integral
capacity
Condition 2
Outdoor heat exchanger
temp. (Tc) (˚CDB)
-10 -5 0 5
-1
-3
-5
-7
Defrost activation range
-9
Above condition for 10 min accumulated.
Outdoor fan is OFF (overload control)
Heating
ESIE02–01
Outside air
temp. (˚CDB)
Max. integral
capacity value
Diminishing
integral capacity
Compr. ON time
Defrosting
Part 2 – Functional Description