IM 1072-1
Water to Water Source Heat Pumps
Page 41 of 44
General Service Guide
All models employ an electromechanical control system for maximum reliability.
Symptom
Possible Trouble
Method of Finding
1. Noisy Operation.
a. Chattering contactor noise.
a. Check contactor points, check for adequate control
voltage from transformer, and check control circuit
for shorts or breaks, check thermostat.
2. Compressor will
a. Lock Out Relay Open.
a. Turn thermostat off, then on.
not start.
b. Loose electrical connections.
b. Check all connections at contactor and compressor
terminal box for loose or burned connection on terminal.
c. Refrigerant charge lost, low pressure
c. Check for R-410A pressure.
cutout open.
d. No control voltage to the compressor
d. Check for 24 volts across contactor coil.
contactor.
If no voltage, check for thermostat circuit trouble
or for compressor safety controls open.
e. Contactor pulled in, but compressor still
e. Check compressor overload circuit, contactor points, etc.
won’t start.
3. Compressor starts but
a. Run capacitor could be bad.
a. Check capacitor.
hums and trips out
on overload.
b. Voltage may be low.
b. Check it.
c. Seized bearings on compressor.
c. Replace compressor.
4. Compressor starts but
a. Low liquid flow (heating cycle).
a. Check liquid flow.
cuts out on low
pressure control.
b. Low refrigerant charge.
b. Remove refrigerant, repair leak and recharge.
c. Restriction in liquid refrigerant line.
c. Check pressures and look for frosting across
the
restriction.
d. Low airflow (cooling cycle).
d. Check and correct.
e. Low pressure cutout may have incorrect
e. Check low pressure cutout for correct pressure.
pressure function.
5. Compressor starts
a. Condenser coils limed or restricted.
a. Check it. (Open systems)
but cuts out on high
pressure control.
b. Malfunctioning high pressure control.
b. Check that the control is cutting out at the correct
pressure.
c. Reduced or lack of liquid flow.
c. Check liquid.
d. Reduced evaporator air flow
d. Check air flow.
(heating cycle).
6. Compressor runs on
a. Reversing valve may be defective.
a. See that it has shifted.
heating cycle,
but does not heat.
b. Thermostat may be defective.
b. Check wiring diagram.
