5.Read liquid line temperature on thermometer; then subtract from bubble point temperature. The difference equals subcooling temperature.
motor on a high platform such as a step ladder. Do not allow motor to hang by its power wires.
6.Compare the subcooling temperature with the normal temperature listed in Table 9. If the measured liquid line temperature does not agree with the required liquid line temperature, ADD refrigerant to raise the temperature or REMOVE refrigerant (using standard practices) to lower the temperature (allow a tolerance of ± 1.7° C).
Refrigerant Charging
To prevent personal injury, wear safety glasses and gloves when handling refrigerant. Do not overcharge system — this can cause compressor flooding.
NOTE: Do not vent or depressurize unit refrigerant to atmo- sphere. Remove and reclaim refrigerant following accepted practices.
Air Coil Fan Motor Removal
Before attempting to remove fan motors or motor mounts, place a piece of plywood over evaporator coils to prevent coil damage.
Disconnect motor power wires from motor terminals before motor is removed from unit.
1. Shut off unit main power supply.
TROUBLESHOOTING
(Fig. 20 and 21, and Table 16)
When troubleshooting problems with a WSHP, consider the following.
Thermistor — A thermistor may be required for single- phase units where starting the unit is a problem due to low voltage. See Fig. 20 for thermistor nominal resistance.
Control Sensors — The control system employs 2 nom- 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. 21.
| 90.0 | |
| 80.0 | |
| 70.0 | |
(kOhm) | 60.0 | |
50.0 | ||
Resistance | ||
40.0 | ||
|
30.0
20.0
10.0
0.0
2.Loosen bolts on mounting bracket so that fan belt can be removed.
3.Loosen and remove the 2 motor mounting bracket bolts on left side of bracket.
4.Slide motor/bracket assembly to extreme right and lift out through space between fan scroll and side frame. Rest
0.020.0 40.0 60.0 80.0 100.0 120.0 140.0 Temperature (degF)
Fig. 20 — Thermistor Nominal Resistance
| AIR |
|
AIRFLOW | COIL | AIRFLOW |
| ||
(°F) |
| (°F) |
THERMISTOR
| EXPANSION | COAX |
| |
| VALVE |
|
| |
FP2 | FP1 |
|
| |
CONDENSATE |
|
|
| |
OVERFLOW | LIQUID |
|
| |
(CO) |
|
| ||
LINE | WATER IN | WATER OUT | ||
| ||||
AIR COIL |
| |||
WATER |
|
| ||
FREEZE |
|
| ||
PROTECTION | COIL |
|
| |
| PROTECTION |
| ||
SUCTION
COMPRESSOR
DISCHARGE
LEGEND
COAX — Coaxial Heat Exchanger
Airflow
Refrigerant Liquid Line Flow
Fig. 21 — FP1 and FP2 Thermistor Location
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