58
G e o t h e r m a l H e a t i n g a n d Co o l i n g
Tranquility
®
30 Digital (TE) Series IOM - 60Hz HFC-410A
R e v. : O c t o b e r 5 , 2 0 2 1
Troubleshooting
Table 17: Nominal resistance at various temperatures
Temp (ºC)
Temp (ºF)
Resistance
(kOhm)
Temp (ºC) Temp (ºF)
Resistance
(kOhm)
-17.8
0.0
85.34
55
131.0
2.99
-17.5
0.5
84.00
56
132.8
2.88
-16.9
1.5
81.38
57
134.6
2.77
-12
10.4
61.70
58
136.4
2.67
-11
12.2
58.40
59
138.2
2.58
-10
14.0
55.30
60
140.0
2.49
-9
15.8
52.38
61
141.8
2.40
-8
17.6
49.64
62
143.6
2.32
-7
19.4
47.05
63
145.4
2.23
-6
21.2
44.61
64
147.2
2.16
-5
23.0
42.32
65
149.0
2.08
-4
24.8
40.15
66
150.8
2.01
-3
26.6
38.11
67
152.6
1.94
-2
28.4
36.18
68
154.4
1.88
-1
30.2
34.37
69
156.2
1.81
0
32.0
32.65
70
158.0
1.75
1
33.8
31.03
71
159.8
1.69
2
35.6
29.50
72
161.6
1.64
3
37.4
28.05
73
163.4
1.58
4
39.2
26.69
74
165.2
1.53
5
41.0
25.39
75
167.0
1.48
6
42.8
24.17
76
168.8
1.43
7
44.6
23.02
77
170.6
1.39
8
46.4
21.92
78
172.4
1.34
9
48.2
20.88
79
174.2
1.30
10
50.0
19.90
80
176.0
1.26
11
51.8
18.97
81
177.8
1.22
12
53.6
18.09
82
179.6
1.18
13
55.4
17.26
83
181.4
1.14
14
57.2
16.46
84
183.2
1.10
15
59.0
15.71
85
185.0
1.07
16
60.8
15.00
86
186.8
1.04
17
62.6
14.32
87
188.6
1.01
18
64.4
13.68
88
190.4
0.97
19
66.2
13.07
89
192.2
0.94
20
68.0
12.49
90
194.0
0.92
21
69.8
11.94
91
195.8
0.89
22
71.6
11.42
92
197.6
0.86
23
73.4
10.92
93
199.4
0.84
24
75.2
10.45
94
201.2
0.81
25
77.0
10.00
95
203.0
0.79
26
78.8
9.57
96
204.8
0.76
27
80.6
9.16
97
206.6
0.74
28
82.4
8.78
98
208.4
0.72
29
84.2
8.41
99
210.2
0.70
30
86.0
8.06
100
212.0
0.68
31
87.8
7.72
101
213.8
0.66
32
89.6
7.40
102
215.6
0.64
33
91.4
7.10
103
217.4
0.62
34
93.2
6.81
104
219.2
0.60
35
95.0
6.53
105
221.0
0.59
36
96.8
6.27
106
222.8
0.57
37
98.6
6.01
107
224.6
0.55
38
100.4
5.77
108
226.4
0.54
39
102.2
5.54
109
228.2
0.52
40
104.0
5.33
110
230.0
0.51
41
105.8
5.12
111
231.8
0.50
42
107.6
4.92
112
233.6
0.48
43
109.4
4.72
113
235.4
0.47
44
111.2
4.54
114
237.2
0.46
45
113.0
4.37
115
239.0
0.44
46
114.8
4.20
116
240.8
0.43
47
116.6
4.04
117
242.6
0.42
48
118.4
3.89
118
244.4
0.41
49
120.2
3.74
119
246.2
0.40
50
122.0
3.60
120
248.0
0.39
51
123.8
3.47
121
249.8
0.38
52
125.6
3.34
122
251.6
0.37
53
127.4
3.22
123
253.4
0.36
54
129.2
3.10
General
If operational difficulties are encountered, perform
the preliminary checks below before referring to the
troubleshooting charts.
• Verify that the unit is receiving electrical supply power.
• Make sure the fuses in the fused disconnect switches
are intact.
After completing the preliminary checks described above,
inspect for other obvious problems such as leaking
connections, broken or disconnected wires, etc. If everything
appears to be in order, but the unit still fails to operate
properly, refer to the “DXM2 Troubleshooting Process
Flowchart” or “Functional Troubleshooting Chart.”
DXM2 Board
DXM2 board troubleshooting in general is best summarized
as verifying inputs and outputs. After inputs and outputs have
been verified, board operation is confirmed and the problem
must be elsewhere. Below are some general guidelines for
troubleshooting the DXM2 control.
Field Inputs
Conventional thermostat inputs are 24VAC from the
thermostat and can be verified using a voltmeter between C
and Y1, Y2, W, O, G. 24VAC will be present at the terminal
(for example, between “Y1” and “C”) if the thermostat is
sending an input to the DXM2 board.
Proper communications with a thermostat can be verified
using the Fault LED on the DXM2. If the control is NOT
in the Test mode and is NOT currently locked out or in
a retry delay, the Fault LED on the DXM2 will flash very
slowly (1 second on, 5 seconds off), if the DXM2 is properly
communicating with the thermostat.
Sensor Inputs
All sensor inputs are ‘paired wires’ connecting each component
to the board. Therefore, continuity on pressure switches,
for example can be checked at the board connector. The
thermistor resistance should be measured with the connector
removed so that only the impedance of the thermistor is
measured. If desired, this reading can be compared to the
thermistor resistance chart shown in Table 17. An ice bath can
be used to check the calibration of the thermistor.
