Component Testing
26
©2007 Viking Preferred Service
Component
Description Test
Procedures
Capacitor
Run capacitor connects to relay
terminal 3 and L side of line.
Some compressors do not require a
run capacitor; refer to the Technical
Data Sheet for the unit being
serviced.
WARNING
To avoid electrical shock which can cause severe
personal injury or death, discharge capacitor
through a resistor before handling.
1. Disconnect power to refrigerator.
2. Remove capacitor cover and disconnect capacitor
wires.
3. Discharge capacitor by shorting across terminals with a
resistor for 1 minute.
4. Check resistance across capacitor terminals with
ohmmeter set on “X1K” scale.
•
Good – needle swings to 0 ohms and slowly moves
back to infinity.
•
Open – needle does not move. Replace capacitor.
•
Shorted – needle moves to zero and stays. Replace
capacitor.
•
High resistance leak – needle jumps toward 0 and then
moves back to constant high resistance (not infinity).
Compressor When
compressor electrical circuit is
energized, the start winding current
causes relay to heat. After an
amount of starting time, the start
winding circuit turns off. The relay
will switch off the start winding circuit
even though compressor has not
started (for example, when
attempting to restart after
momentary power interruption).
With “open” relay, compressor will
not start because there is little or no
current to start windings. Overload
protection will open due to high
locked rotor run winding current.
With “shorted” relay or capacitor,
compressor will start and overload
protector will quickly open due to
high current of combined run and
start windings.
With open or weak capacitor,
compressor will start and run as
normal but will consume more
energy.
Resistance test
1. Disconnect power to unit.
2. Discharge capacitor by shorting across terminals with a
resistor for 1 minute.
NOTE:
Some compressors do not have a run capacitor.
3. Remove leads from compressor terminals.
4. Set ohmmeter to lowest scale.
5. Check for resistance between
•
Terminals “S” and “C”, start winding
•
Terminals “R” and “C”, run winding
If either compressor winding reads open (infinite or very
high resistance) or dead short (0 ohms), replace
compressor.
Ground test
1. Disconnect power to refrigerator.
2. Discharge capacitor, if present, by shorting terminals
through a resistor.
3. Remove compressor leads and use an ohmmeter set on
highest scale.
4. Touch one lead to compressor body (clean point of
contact) and other probe to each compressor terminal.
NOTE:
If reading is obtained, compressor is grounded and
must be replaced.
