Mitsubishi Electric CITY MULTI PUHY-400YMF-B Service Handbook page 104

(11) Liquid Refrigerant Correction Control
The liquid refrigerant correction control adjusts the liquid refrigerant amounts between both accumulators in the
unlikely event that the liquid refrigerant amount in both the constant and variable capacity unit accumulators should
be insufficient, or if and excessive amount of liquid refrigerant is returned from either accumulator.
During this operation, Service LED No. 4 on the variable capacity unit will light up.
Direction of Accumula-
tor Liquid Transfer
Variable Capacity Unit • In heating mode
Constant Capacity Unit • Run and stop indoor units
↓ are mixed.
• Pd
Indoor Unit
during an accumulator
overflow preliminary error.
• Td < 110°C
• In heating mode
Variable Capacity Unit
• While the constant capacity
↓
unit is stopped.
Constant Capacity Unit
• During an accumulator
overflow preliminary error
in the variable capacity unit
(AL1 = 2)
• TdSH < 40 deg *1
• In heating mode
Variable Capacity Unit
• During constant capacity
↓
unit operation
Constant Capacity Unit
• When AL1 = 2 is detected in
the variable capacity unit.
• TdSH < 40 deg *1
• In cooling mode
Variable Capacity Unit
• While the constant capacity
↓
unit is stopped.
Constant Capacity Unit
• During an accumulator
overflow preliminary error
in the variable capacity unit
(AL1 = 2)
• Constant capacity unit
AL2 = 0 or 1
• Variable capacity unit
TH6 < 25°C
Variable Capacity Unit
• In heating mode
↓ • Constant capacity unit
switches from operation to
Constant Capacity Unit
stopping.
• Constant capacity unit AL2 = 0
• In heating mode
Constant Capacity Unit
• During an accumulator
↓
overflow error delay in the
Variable Capacity Unit
constant capacity unit
(AL2 = 2)
• Variable capacity unit
AL1 = 0 or 1
Constant Capacity Unit • During cooling or heating
↓ • During an accumulator
overflow preliminary error
Variable Capacity Unit
in the constant capacity
unit (AL2 = 2)
• Variable capacity unit
AL1 = 0 or 1
* 1 TdSH (Discharge temperature superheating) = Discharge temperature (TH11 or TH12) - Tc (High pressure saturation
Constant Capacity Unit
Start Conditions
Com-
pressor
–
13k (1.27 MPa), or
OFF
OFF
OFF
OFF
–
OFF
temperature)
Actuator Action
Variable
capacity
LEV2 SV5b Other
unit
– – – –
2000 ON – –
(open)
2000 ON – –
(open)
2000 ON Fan Opera-
(open) ON tion
fre-
quency
level
up
2000 ON – –
(open)
– – – Opera-
tion
fre-
quency
level
down
2000 ON LEV1 = 21S4a,
(open) 480 b
SV4 ON ON
21S4
OFF
–101–
Stopping LED Monitor
Indoor
Conditions No.4
Unit
Opera- While all • Verify
tion: indoor units surplus
nor- are operat- refrigerant
mal ing • LD1 lights
control Td 115°C up
Stop:
LEV = 60
– • AL1 = 0 or 1 Liquid
• Continuing refrigerant
control 2
for 20
minutes LD3 lights
up
– • AL1 = 0 or 1 Liquid
• AL2 = 2 refrigerant
• Continuing control 4
for 10 LD5 lights
minutes up
All • AL1 = 0 or 1 Liquid
indoor • Continuing refrigerant
control 6
unit for 15
LEV = 60 minutes LD7 lights
up
– • AL1 = 0 or 1 Liquid
• Continuing refrigerant
control 7
for 3 ~ 6
minutes LD8 lights
up
– • AL2 = 0 or 1 Liquid
• AL1 = 2 refrigerant
control 3
• Continuing
for 10 LD4 lights
minutes up
All • AL1 = 2 Liquid
indoor • Continuing refrigerant
control 5
unit for 4
LEV = 60 minutes LD6 lights
up