Troubleshooting; Thermistor; Control Sensors - Carrier AQUAZONE 50HQL072-120 Installation, Start-Up And Service Instructions Manual

TROUBLESHOOTING

(Fig. 18 and 19, and Table 27)
When troubleshooting problems with a WSHP, consider the
following:
A thermistor may be required for single-
Thermistor —
phase units where starting the unit is a problem due to low
voltage. See Fig. 18 for thermistor nominal resistance.
The control system employs 2 nom-
Control Sensors —
inal 10,000 ohm thermistors (FP1 and FP2) that are used for
freeze protection. Be sure FP1 is located in the discharge fluid
and FP2 is located in the air discharge. See Fig. 19.
AIR
COIL
AIRFLOW
(°F)

THERMISTOR

CONDENSATE
OVERFLOW
(CO)
AIR COIL
FREEZE
PROTECTION
LEGEND
COAX — Coaxial Heat Exchanger
Airflow
Refrigerant Liquid Line Flow
AIRFLOW
(°F)
EXPANSION
VALVE
FP2 FP1
LIQUID
LINE
WATER IN
WATER
COIL
PROTECTION
Fig. 19 — FP1 and FP2 Thermistor Location
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
0.0 20.0
Fig. 18 — Thermistor Nominal Resistance
COAX
WATER OUT
39
40.0 60.0 80.0 100.0 120.0
Temperature (degF)
SUCTION
COMPRESSOR
DISCHARGE
a50-8163
140.0