Automatic Pumpdown - Daikin LX10F11B3 Service Manual

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4.2 Automatic Pumpdown

An automatic pump down is performed to prevent damage to compressor due to extremely low suction
pressure.
●Access to Automatic Pumpdown
Operation display Select Service Menu
FROZEN FULL COOL
SET POINT
SET-MODE
Setpoint
-18.0C
Menu
RETURN
-18.1C
Service Menu
SUPPLY -18.6C DEF-INT 12HR
▲
HP:1200KP LP: 20KPa
▼
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)
●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
① ② ③
kPa
30s
20s
＋
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.
Select Auto Pumpdown
Menu Service Menu
Trip Start
Auto P.down
④ ⑤
LPT
40s
0〜350kPa
0kPa
−27kPa
Auto Pump down
Press
ENTER to Start
ESC to Cancel
2. "GOOD" is displayed after completion of
automatic pump down. Then press I/O switch
OFF for the termination.
●Use of Automatic Pumpdown
1. Replacement of Dryer
Replace Dryer after automatic pump down
is completed. The pressure in the pipe in
and out of the Dryer is slightly higher than
the atmospheric pressure. Thus, although no
ambient air will enter into the piping, replace
Dryer quickly in a short period.
CAUTION !!
Ambient air may enter into piping if it is opened
for long time after removing Dryer. In this
case vacuum and dehydrate the piping after
replacement of Dryer.
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.)
LPT
HSV
DMV
4-6
Auto Pumpdown
Under preparation
During operation
Note 1
Auto Pump down
Auto Pump down
Pump Down
Preparation
Activated
EEV
Dryer
CFM
③
LSV
Service
port
0〜350 kPa after completion
of automatic pumpdown