Compressor will not run.
a) Main switch open. Circuit breakers open	a) Close switch
b) Fuse blown	b) Check electrical circuits and motor winding for shorts or grounds. Investigate for possible overloading. Replace fuse or reset breakers after fault is corrected.
c) Thermal overloads tripped or fuses blown	c) Overloads are auto. reset. Check unit closely when unit comes back on line.
d) Defective contactor or coil	d) Repair or replace
e) System shut down by safety devices	e) Determine type and cause of shut-down and correct it before resetting safety switch.
f) No cooling required	f) None. Wait until unit calls for cooling.
g) Liquid line solenoid will not open	g) Repair or replace coil
h) Motor electrical trouble	h) Check motor for opens, short circuit, or burnout
i) Loose wiring	i) Check all wire junctions. Tighten all terminal screws.

Compressor noisy or vibrating.
a) Flooding of refrigerant into crankcase	a) Check setting of expansion valve
b) Improper piping support on discharge coil or liquid line*	b) Relocate, add, or remove hangers
c) Worn compressor	c) Replace

High Discharge Pressure
a) Condenser water insufficient or temperature too high	a) Readjust water regulating valve. Investigate ways to increase water supply
b) Fouled condenser tubes (water cooled condenser). Clogged spray nozzles (evaporative condenser). Dirty tube and fin surface (air cooled condenser)	b) Clean
c) Non-condensibles in system	c) Purge the non-condensibles
d) System overcharged with refrigerant*	d) Remove excess
e) Discharge shut off valve partially dosed	e) Open valve
f) Condenser undersized*	f) Check condenser rating tables against the operation
g) High ambient conditions*	g) Check condenser rating tables against the operation

Discharge Pressure
a) Faulty condenser temperature regulation	a) Check condenser control operation
b) Suction shut-off valve partially closed	b) Open valve
c) Insufficient refrigerant in system	c) Check for leaks. Repair and add charge
d) Low suction pressure	d) See Corrective Steps for low suction pressure below
e) Compressor operating unloaded	e) See Correction Steps for failure of compressor to load up below
f) Condenser too large*	f) Check condenser rating table against the operation
g) Low ambient conditions*	g) Check condenser rating tables against the operation

Suction Pressure
a) Lack of refrigerant	a) Check or leaks. Repair and add charge
b) Evaporator dirty	b) Clean chemically
c) Clogged liquid line filter-drier	c) Replace cartridge(s)
d) Clogged suction line or compressor suction gas strainers	d) Clean strainers
e) Expansion valve malfunctioning	e) Check and reset for proper superheat. Replace if necessary
f) Condensing temperature too low	f) Check means for regulating condensing temperature
g) Compressor will not unload	g) See Corrective Steps for failure of compressor to unload
h) Insufficient water flow	h) Adjust gpm.

Compressor will not unload or load up
a) Defective capacity control	a) Replace
b) Unloader mechanism defective	b) Replace
c) Faulty thermostat stage or broken capillary tube	c) Replace
d) Stages not set for application	d) Reset thermostat setting to fit application

Compressor Loading - Unloading Intervals too short
a) Erratic water thermostat	a) Replace
b) Insufficient water flow	b) Adjust gpm.

Little or no oil pressure
a) Clogged suction oil strainer	a) Clean
b) Excessive liquid in crankcase	b) Check crankcase heater. Reset expansion valve for higher superheat. Check liquid line solenoid valve operation
c) Oil pressure gauge defective	c) Repair or replace. Keep valve closed except when taking readings
d) Low-oil pressure safety switch defective	d) Replace
e) Worn oil pump	e) Replace
f) Oil pump reversing gear stuck in wrong position	f) Reverse direction of compressor rotation
g) Worn bearings	g) Replace compressor
h) Low oil level	h) Add oil
i) Loose fitting on oil lines	i) Check and tighten system
j) Pump housing gasket leaks	j) Replace gasket
k) Flooding of refrigerant into crankcase	k) Adjust thermal expansion valve

Compressor loses oil
a) Lack of refrigerant	a) Check for leaks and repair. Add refrigerant
b) Velocity in risers too low*	b) Check riser sizes
c) Oil trapped in line*	c) Check pitch of lines and refrigerant velocities
d) Excessive compression ring blow-by	d) Replace compressor

Motor overload relays or circuit breakers open
a) Low voltage during high load conditions	a) Check supply voltage for excessive line drop
b) Defective or grounded wiring in motor or power circuits	b) Replace compressor motor
c) Loose power wiring	c) Check all connections and tighten
d) High condensing temperature	d) See Corrective Steps for high discharge pressure
e) Power line fault causing unbalanced voltage	e) Check supply voltage. Notify power company.Do not start until fault is corrected
f) High ambient temperature around the overload relay	f) Provide ventilation to reduce heat
g) Failure of second starter to pull in on part-winding start system	g) Repair of replace starter or time delay mechanism

Compressor thermal protector switch open
a) Operating beyond design conditions	a) Add facilities so that conditions are within allowable limits
b) Discharge valve partially shut	b) Open valve
c) Blown valve plate gasket	c) Replace gasket

Freeze protection opens
a) Thermostat set too low	a) Reset to 40 F or above
b) Low water flow	b) Adjust gpm.
c) Low suction pressure	c) See "Low Suction Pressure"

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