Trouble
Compressor short cycles on
low- pressure control.
Possible Cause
Corrective Measure
Low refrigerant charge.
Locate and repair leaks.
Charge refrigerant.
Thermal expansion valve not
Adjust, repair or replace thermal
feeding properly.
expansion valve.
(a) Dirty strainers.
(a) Clean strainers.
(b) Moisture frozen in orifice or
(b) Remove moisture or dirt (use
orifice plugged with dirt.
system dehydrator).
(c) Power element dead or weak
(c) Replace power element.
Water flow through evaporators
Remove restriction. Check water flow.
restricted or stopped. Evaporator coils
Clean coils or tubes.
plugged, dirty, or clogged with frost.
Defective low-pressure control switch.
Repair or replace low-pressure control
switch.
Compressor runs continuously.
Shortage of refrigerant.
Repair leak and recharge system.
Leaking discharge valves.
Replace discharge valves.
Compressor short cycles on
Insufficient water flowing through
Determine if water has been turned
high- pressure control switch.
condenser, clogged condenser.
off. Check for scaled or fouled
condenser.
Defective high-pressure control switch. Repair or replace high-pressure
control switch.
Compressor will not run.
Seized compressor.
Repair or replace compressor.
Cut-in point of low-pressure control
Set L. P. control switch to cut-in at
switch too high.
correct pressure.
High-pressure control switch does not
Check discharge pressure and reset H.
cut-in.
P. control switch.
1.
Defective switch.
1.
Repair or replace switch.
2.
Electric power cut off.
2.
Check power supply.
3.
Service or disconnect switch
3. Close switches.
open.
Figure 5-8.—Trouble diagnosis chart-Continued.
5-14
