Friedrich SH20L30-B ユーザーズマニュアル

9

Compressor attempts to start 
before system pressures are 
equalized.

Allow a minimum of two (2) minutes to allow pressures to 
equalize before attempting to start.

Low or fl uctuating voltage.

Check voltage with unit operating. Check for other 
appliances on the circuit. Unit should be on separate circuit 
for proper voltage, and be fused separately.

Incorrect wiring.

Connect per wiring diagram.

Shorted or incorrect capacitor.

Check by substituting a known good capacitor of correct 
rating.

Restricted or low air fl ow through 
condenser coil.

Check for proper fan speed or blocked condenser.

Compressor running abnormally 
hot.

Check for kinked discharge line or restricted condenser. 
Check amperage.

Overload opens too soon.

Change compressor if all other corrections above are 
normal.

Thermostat contacts not closing.

Check continuity of thermostat at coldest setting. Jump 
contacts, if compressor runs, replace thermostat.

Low voltage supply.

Check for nameplate voltage.

Switch (On-Off) inoperative.

Test for continuity.

Open capacitor.

Check by substituting a known good capacitor of correct 
rating.

Internal overload open.

Check voltage at compressor terminals. If voltage is 
satisfactory, replace compressor.

Relay open

Replace relay

Open or shorted compressor 
windings

Check windings for continuity and resistance. Direct test 
compressor. If direct test fails, replace compressor.

Thermostat open or inoperative.

Set to coldest position. Test thermostat and replace if 
necessary.

Dirty air fi lter.

Clean as recommended in Owner’s Manual.

Dirty or plugged condenser or 
evaporator coil.

Use steam or detergents to clean.

Poor air circulation in area being 
cooled.

Adjust air louvers.

Low capacity - undercharge.

Clean, check for leak and make repair.

Compressor not pumping properly.

Check amperage draw against nameplate. If not conclusive, 
make pressure test.