114 RT-SVD03G-EN
Electromechanical Economizer Testing
Electromechanical Mixed Air Sensor
When the outdoor air thermostat is in the cold position (closed), the unit will attempt to economize
if a fan (G) and cooling (Y1) call exists at the ECA module. This is readily apparent at the ECA, as
the “OK to economize” LED will be on. During this time, the ECA is measuring the Mixed Air
temperature via the Mixed Air Sensor (MAS).
Service Tips
The MAS sensor is not energized unless the LED is on (G signal present, OK to economize), and the
Y1 signal is present.
If the MAS is open, approximately 4.3 VDC will be seen.
Outdoor Air Thermostat opens at 70°F and closes at 60°F.
Read the voltage with the sensor connected, read the resistance with the sensor disconnected.
Table 42. Temperature Input
Temp F Temp C R(K OHMS) DC Volts Temp F Temp C R(K OHMS) DC Volts
33.8 1 9.576 3.910 89.6 32 2.204 2.714
35.6 2 9.092 3.882 91.4 33 2.111 2.676
37.4 3 8.636 3.894 93.2 34 2.023 2.639
39.2 4 8.204 3.863 95.0 35 1.938 2.600
41.0 5 7.796 3.829 96.8 36 1.858 2.561
42.8 6 7.412 3.790 98.6 37 1.781 2.526
44.6 7 7.048 3.749 100.4 38 1.708 2.484
46.4 8 6.705 3.713
48.2 9 6.380 3.674
50.0 10 6.073 3.634
51.8 11 5.782 3.590
53.6 12 5.507 3.550
55.4 13 5.247 3.507
57.2 14 5.000 3.420
59.0 15 4.767 3.373
60.8 16 4.545 3.328
62.6 17 4.335 3.283
64.4 18 4.136 3.239
66.2 19 3.948 3.180
68.0 20 3.769 3.157
69.8 21 3.599 3.118
71.6 22 3.437 3.080
73.4 23 3.284 3.034
75.2 24 3.138 3.007
77.0 25 3.000 2.971
78.8 26 2.869 2.932
80.6 27 2.744 2.896
82.4 28 2.625 2.860
84.2 29 2.512 2.824
86.0 30 2.404 2.787
87.8 31 2.301 2.750
To Next Page
Loading...
