Mitsubishi Electric CITY MULTI PUHY-400YMF-B, Service Handbook

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1
Detects the outdoor air temperature.
2 Performs fan control, liquid level
heater control, opening settings of
LEV for oil return and other functions.
Controls LEV using temperature differ-
ences among TH5, TH7, TH8 and TH9a.
1) Detects the CS circuit fluid tempera-
ture.
2) Calculates the refrigerant circulation
configuration.
Performs constant capacity unit LEV2
control by comparing the temperature
difference with low pressure saturation
temperature.
1) Detects the compressor shell
temperature.
2) Provides compressor shell over-
heating protection.
Inverter cooling fan control using THHS
temperature.
1 Capacity control of high/low
pressure bypass when starting and
stopping.
2
Discharge pressure rise suppression.
Switching of capacity control valve inside
No. 2 compressor (Switching between
full load operation and unload operation)
(All but model PUHY-400 YMF-B).
Capacity control and controlling the rise
of high-pressure (Back-up of frequency
control).
Thermistor
Solenoid
valve
R
0
= 15 k
Ω
B
1/80
= 3460
Rt =
15exp{3460( - )}
0
°
C: 15 k
Ω
10
°
C: 9.7 k
Ω
20
°
C: 6.4 k
Ω
25
°
C: 5.3 k
Ω
30
°
C: 4.3 k
Ω
40
°
C: 3.1 k
Ω
R
120
= 7.465 k
Ω
B
25/120
= 4057
Rt =
7.465exp
{4057( - )}
20
°
C: 250 k
Ω
70
°
C: 34 k
Ω
30
°
C: 160 k
Ω
80
°
C: 24 k
Ω
40
°
C: 104 k
Ω
90
°
C: 17.5 k
Ω
50
°
C: 70 k
Ω
100
°
C: 13.0 k
Ω
60
°
C: 48 k
Ω
110
°
C: 9.8 k
Ω
R
50
= 17 k
Ω
B
25/120
= 4170
Rt =
17exp {4170 ( - )}
0
°
C: 181 k
Ω
10
°
C: 105 k
Ω
20
°
C: 64 k
Ω
25
°
C: 50 k
Ω
30
°
C: 40 k
Ω
40
°
C: 26 k
Ω
AC 220 to 240 V
Open : conducting
Close: not conducting
AC 220 to 240 V
Close: conducting
Open : not conducting
AC 220 to 240 V
Open : conducting
Close: not conducting
Resistance check
Resistance check
Conductivity test
using tester
TH6
(Outdoor
temperature)
TH7
TH8
TH9a
(SC control)
TH9b
(PUHY-
P400·500
YMF-B only)
TH10a
TH10b
Heat
exchanger
Gas tempera-
ture
TH10c
(PUHY-
P400·500
YMF-B only)
THHS inverter
heat sink tem-
perature
SV1
discharge-
suction
bypass
SV22
capacity
control (full
load)
SV32
capacity
control
(unload)
SV4
discharge-
suction
bypass
Outdoor unit (V
ar
iab
le capacity unit)
R
0
= 15 k
Ω
B
1/80
= 3460
Rt =
15exp{3460( - )}
0
°
C: 15 k
Ω
10
°
C: 9.7 k
Ω
20
°
C: 6.4 k
Ω
25
°
C: 5.3 k
Ω
30
°
C: 4.3 k
Ω
40
°
C: 3.1 k
Ω
Name
Code
(Function)
Inspection method Application Product code Specification
1
273+t
1
273
TH3
TH4
(Liquid level
detection)
TH5
(Liquid pipe
temperature)
Detects liquid level of refrigerant inside
accumulator using the differences
among TH2, TH3, TH4.
1
Frequency control.
2 Controls defrosting during heating.
3 Detects sub-cool of heat exchanger
outlet using 63HS data and TH5 to
control LEV1.
1
273+t
1
273
1
273+t
1
273+120
1
273+t
1
323
Resistance check