Daikin LX10F10A, Service Manual

Page: 95 / 126

4-6
4.2 Automatic Pumpdown
An automatic pump down system is applied to the unit to prevent the unit from extra decrease of low pressure
due to pump down operation or burning of scroll compressor due to a closed stop valve.
●
Access to Automatic Pumpdown
Note ;
1. When PTI starts soon after pressing I/O switch ON,
"Preparation" is displayed due to actuation of start
control. (Refer to startup control in paragraph 1.4.6)
2. "GOOD" is displayed after completion of
automatic pump down. Then press I/O switch
OFF for the termination.
●
Automatic Pumpdown Operation
Automatic Pump Down operation consists of
5 steps as below. It is normally terminated for
a several minutes but more longer under low
ambient temperature (
≦ 0 ℃ ).
LPT
kPa
− 27kPa
LPT
0 〜 350kPa
① ② ③ ④ ⑤
0kPa
30s
20s
40s
＋
0
−
① In the case of HPT ≦ 700kPa, unit operates
normally for 30 seconds.
② Pump Down Operation
Unit conducts pump down operation with
closing LSV and compressor will stop when
LPT drops to
≦ -27kPa.
③ Leakage Check
Keep unit stopping for 20 seconds and check if
LPT does not rise.
Repeat
② and ③ 9 times when ambient
temperature<0 ℃ or RS<0 ℃ .
④ Pressure Equalizing
Keep EFM and CFM stopping for 40 seconds,
then if LPT<0kPa, open HSV and increase
LPT until LPT
≧ 0 〜 350kPa.
⑤ Termination
Close HSV when LPT becomes 0
〜 350kPa,
then close EEV. "GOOD" is displayed and
automatic pumpdown will be terminated.
CAUTION !!
If unit stops at step ① or ② above and triggers
alarm E202, overcharged refrigerant may be
caused.
In this case, recover the refrigerant from service
port
③ until the pressure drops 0 to 350 kPa.
(Closed circuit between LSV and EEV)
Replace drier after that.
●
Use of Automatic Pumpdown
1. Replacement of drier
Replace drier after automatic pump down is
completed. The pressure in the pipe in and
out of the drier is slightly higher than the
atmospheric pressure. Thus, although no
ambient air will enter into the piping, replace
drier quickly in a short period.
CAUTION !!
Ambient air may enter into piping if it is opened
for long time after removing drier. In this
case vacuum and dehydrate the piping after
replacement of drier.
2. Checking the entering of non-condensable gas
After completion of automatic pumpdown,
operate CFM and stabilize the pressure in
condenser, then check the entering of non-
condensable gas. (Refer to paragraph 4.4.)
0 〜 350 kPa after completion
of automatic pumpdown
Drier
EEV
HSV
LSV
DMV
LPT
CFM
③
Service
port
Preparation
Under preparation
Note 1
Auto Pump down
SET-MODE SET POINT
SET-HU 70%RH HUMID 75%RH
SUPPLY -18.6C DEF-INT 12HR
DEHUMID
USDA
-18.0C
FULL COOL FROZEN
HP:1200KP LP: 20KPa
▲
▼
RETURN
-18.1C
Operation display
Menu
Service Menu
Trip Start
Auto P.down
Menu
Setpoint
Service Menu
Auto Pump down
Pump Down
Activated
Auto Pumpdown
During operation
Auto Pump down
Press
ENTER to Start
ESC to Cancel
Select Service Menu Select Auto Pumpdown