Emerson ALCO CONTROLS HP Serie Instrucciones De Utilizacion página 2

3. System fails to start or short cycles on
low pressure failure switch after off-cycle
or defrost
Fig. 1
Fig. 4
Fig. 7
Document Nr.: A6.5.059 -
Obstruction or valve closed in discharge or condenser
drain line
Liquid line solenoid valve fails to open
Receiver exposed to low ambient on outdoor
condensing unit during off-cycle or defrost
Thermo valve fails to feed due to loss o f charge or
other reason
Oil pump failing to develop oil pressure due to viscous
oil in exposed crankcase
Liquid solenoid valve failing to open or thermostat fails
to make contact
Defrost control fails to terminate defrost
Receiver pressure approaching low pressure control in
cut-in setting because:
Insufficient refrigerant to maintain some liquid in
receiver or remote condenser system during off-cycle
Oil congealing in low pressure control or oil pressure
failure. Switch cap tubes where exposed to low
ambient
Fig. 2
Fig. 5
Fig. 8
Replacement for x...
Clear obstruction or open valve
Check solenoid valve
Shorten off-cycle time of defrost time if possible or add
receiver insulation. If long off-cycles are required
receiver heat may also be required. Time delay relay
may also be used.
Change or repair Thermo valve.
Add crankcase heater
Change or repair solenoid or thermostat.
Change or repair solenoid or thermostat.
Add refrigerant or optional check valve. Time delay
relay to by -pass LP control on start-up may also be
used. Set for 2-3 minutes forced run.
Change cap tube to ¼"/6mm copper tube.
Fig. 3
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Fig. 9
Date: 28.04.2003 DWG Nr.: EA/PCN 861376