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52 Packaged Heat Pump • WC-IOM-7
Troubleshooting
Zone Temperature Sensor (ZTS) Test
Note: These procedures are not for programmable or digital models and are
conducted with the Zone Sensor Module electrically removed from the
system.
Te s t 1
Zone Temperature Thermistor (ZTEMP)
This component is tested by measuring the resistance between terminals 1 and 2
on the Zone Temperature Sensor. Below are some typical indoor temperatures,
and corresponding resistive values.
Te s t 2
Cooling Set Point (CSP) and Heating Set Point (HSP)
The resistance of these potentiometers are measured between the following
ZSM terminals. Refer to the chart above for approximate resistances at the given
setpoints.
Cool SP = Terminals 2 and 3
Range = 100 to 900 Ohms approximate
Heat SP = Terminals 2 and 5
Range = 100 to 900 Ohms approximate
Table 8.
Zone Temperature
Nominal
ZTEMP
Resistance
Nominal CSP
or HSP
Resistance
50 F° 10.0 C° 19.9 K-Ohms 889 Ohms
55 F° 12.8 C° 17.47 K-Ohms 812 Ohms
60 F° 15.6 C° 15.3 K-Ohms 695 Ohms
65 F° 18.3 C° 13.49 K-Ohms 597 Ohms
70 F° 21.1 C° 11.9 K-Ohms 500 Ohms
75 F° 23.9 C° 10.50 K-Ohms 403 Ohms
80 F° 26.7 C° 9.3 K-Ohms 305 Ohms
85 F° 29.4 C° 8.25 K-Ohms 208 Ohms
90 F° 32.2 C° 7.3 K-Ohms 110 Ohms