McQuay MDS Series User Manual

Service Manual SM-MDS_(ii) 15
MDS-M PCB
Remark:
No
No
1
7 Segment LED Display
14
FX1-OL - Fix compressor overload
2
Reset Button
DIG-OL - Digital compressor overload
3
PCB Software Version
LP - Low pressure switch
4
MDS-M PCB
HP - High pressure switch
5
A
in
& B
in
(To indoor)
N - Neutral
6
A
pc
& B
pc
(Centralize Control)
L - Live
7
Dipswitch 1 (S1)
15
Transformer Output
8
Dipswitch 2 (S2)
16
TH7 - Midlet coil temperature sensor (3
rd
)
9
Dipswitch 3 (S3)
TH6 - Inlet coil temperature sensor (3
rd
)
10
K1, K2, K3 & K4 Buttons
TH5 - Midlet coil temperature sensor (2
nd
)
11
FIX - Fix compressor
TH3 - Midlet coil temperature sensor (1
st
)
DIG - Digital compressor
17
TH12 - Return air temperature sensor
12
LO FAN
TH11 - SCC bypass sensor
HI FAN
TH10 - After SCC sensor
4WV - Four way valve
TH9 - Before SCC sensor
13
PWM - Pulse Width Modulation
18
TH8 - Outdoor ambient sensor
TH4 - Inlet coil temperature sensor (2
nd
)
TH2 - Inlet coil temperature sensor (1
st
)
19
TH1 - Digital compressor discharge sensor
20
LOW-U - Low pressure
21
HI-U - High pressure
MDS-M PCB is used in all (5)MDS-B/BR series outdoor unit (except 5MDS 50/60/70B/BR). The
figure above shows the locations for all dipswitches, buttons, electrical connections and sensor
connections.
Remark: When K1 button is pressed, unit is forced to run defrost cycle. When K4 button is
pressed (when unit in standby condition), all EXV valve will open. To exit these states, simply
press on the Reset button.
3
13
12
11
7
8
9
6
5
4
3
2
1
21
20
19
18
17
16
15
14
10

McQuay MDS Series Specifications

General

Brand	McQuay
Model	MDS Series
Category	Compressor
Language	English