25
RSMD Technical Guide
TROUBLESHOOTING
Suction Pressure Transducer Testing
Suction Pressure Transducer Testing
for R410-A Refrigerant
The Evaporator Coil Temperature is calculated by converting
the Suction Pressure to Temperature. The Suction Pressure is
obtained by using the Suction Pressure Transducer, which is
connected into the Suction Line of the Compressor.
Use the voltage column to check the Suction Pressure Transducer
while connected to the RSMD Module(s). The VCCX2 and the
RSMD Module(s) must be powered for this test. Read voltage
with a meter set on DC volts. Place the positive lead from the
meter on the SP1/SP2 terminal located on the RSMD Module(s)
terminal block. Place the negative lead from the meter on the
ground (GND) terminal located adjacent to the SP1/SP2 terminal
on the RSMD Module(s) terminal block. Use a refrigerant gauge
set and/or an accurate electronic thermometer to measure the
temperature or suction line pressure near where the Suction
Pressure Transducer is connected to the suction line. Measure
the Voltage at the SP1/SP2 and GND terminals and compare it to
the appropriate chart depending on the refrigerant you are using.
If the temperature/voltage or pressure/voltage readings do not
align closely with the chart, your Suction Pressure Transducer
is probably defective and will need to be replaced.
See the Suction Pressure Transducer, Pressure, Temperature, and
Voltage Chart for R410-A Refrigerant testing. The charts show
a temperature range from 20°F to 80°F. For troubleshooting
purposes, the DC Voltage readings are also listed with their
corresponding temperatures and pressures.
Table 4: Coil Pressure/Voltage/Temp for Suction
Pressure Transducers - R410-A Refrigerant
Suction Pressure
Transducer Coil
Pressure – Temperature – Voltage Chart for
R410-A Refrigerant
Temperature °F
Temperature
ºC
Pressure
PSI
Signal
DC V
olts
21.19
-6.1
80.94
1.8
24.49
-4.4
87.16
1.9
27.80
-2.8
93.39
2.0
30.99
-1.1
99.62
2.1
33.89
0.6
105.84
2.2
36.80
2.2
112.07
2.3
39.71
3.9
118.29
2.4
42.30
5.6
124.52
2.5
44.85
6.7
130.75
2.6
47.39
8.3
136.97
2.7
49.94
9.4
143.2
2.8
52.23
11.1
149.42
2.9
54.50
12.2
155.65
3.0
56.76
13.3
161.88
3.1
59.03
15
168.10
3.2
61.17
16.1
174.32
3.3
63.19
17.2
180.55
3.4
65.21
18.3
186.78
3.5
67.23
19.4
193.00
3.6
69.24
20.6
199.23
3.7
71.15
21.7
205.46
3.8
72.95
22.2
211.68
3.9
74.76
23.3
217.91
4.0
76.57
24.4
224.14
4.1
78.37
25.6
230.36
4.2
80.18
26.7
236.59
4.3
Summary of Contents for RSMD
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