Fujitsu ASU18RLF Service Manual

3. Defrost Flow Chart
The defrosting shall proceed by the integrating operation time, outdoor temperature
and outdoor heat exchanger temperature as follows.
3 sec later Compressor : OFF
3 sec later Outdoor fan motor : OFF
35sec later 4WAY valve : OFF
41sec later Compressor : ON
Heating operation start : Compressor ON
Outdoor HEX temp. : Over 59°F(15°C)
Compressor ON time : Maximum 15 minutes
Defrost end
Defrost Indicator:
[Operation lamp]
7 sec ON / 2 sec OFF
Defrost start
Tn < 1.4°F(-17°C)
Ta > 14°F(-10°C)
Tn < 0.8 ×Ta - 11.6
Tn < -18.4°F(-28°C)
=
=
Tn - Tn-1 < 28.4°F(-2°C)
and Sn = Sn-1
=
Ta < 4°F(-20°C)
Normal defrost Integrating defrost Integrating defrost
(Integrating OFF count defrost)
4°F(-20°C) < Ta < 14°F(-10°C)
Tn < 21.2°F(-6°C) More than 210 minutes
( For continuous operation )
or
Tn < 26.6°F(-3°C)
(and after 30 minutes,
if the Tn < 26.6°F(-3°C)
(and after 3 minutes,
if the Tn < 23°F(-5°C)
Tn < 23°F(-5°C)
or
=
=
Tn < 0.8 ×Ta - 11.6
Tn < -18.4°F(-28°C)
=
=
=
Compressor OFF count :
40 times
(Less than 10 minutes)
or or
Tn
Ta
Tn-1
Sn
Sn-1
: Outdoor heat exchanger temp.
: Outside air temp.
: Before 5 minutes detected Tn
: Number of operation indoor units
: Before 5 minutes detected Sn
01-27

Fujitsu ASU18RLF Specifications

General

Brand	Fujitsu
Model	ASU18RLF
Category	Air Conditioner
Language	English