Component Testing
!
WARNING
To avoid risk of electrical shock, personal injury, or death, disconnect electrical power source to unit, unless test
procedures require power to be connected. Discharge capacitor through a resistor before attempting to service.
Ensure all earthing wires are connected before certifying unit as repaired and/or operational.
©2004 Maytag Services
16023324 Rev. 0
9
Component Description
Test
Procedures
Evaporator
Inner volume of evaporator allows liquid
refrigerant discharged from capillary to
expand into refrigerant gas.
Expansion cools evaporator tube and fin
temperature to approximately -20
°
F
transferring heat from freezer section to
refrigerant.
Passing through suction line to
compressor, the refrigerant picks up
superheat (a relationship between
pressure and temperature that assures
complete vaporization of liquid
refrigerant) as the result of capillary tube
soldered to suction line.
Refrigerant gas is pulled through suction
line by compressor, completing
refrigeration cycle.
Test for leaks in evaporator with electronic leak detector or with soap solution.
Compressor oil is circulated with refrigerant; check for oil when checking for
leaks.
For minute leaks:
1. Separate evaporator from rest of refrigeration system and pressurize
evaporator up to a maximum of 9.65 Bar with a refrigerant and dry nitrogen
combination.
2. Recheck for leaks.
Evaporator heater
(defrost)
Activated when defrost thermostat,
defrost timer, and freezer control
complete circuit through heater.
Check resistance across heater.
To check defrost system:
1. Thermocouple defrost thermostat and plug refrigerator into wattmeter.
2. Turn into defrost mode. Wattmeter should read specified watts (according to
Technical Data Sheet).
3. When defrost thermostat reaches specified temperature
±
15
°
C (see
Technical Data Sheet), thermostat should interrupt power to heater.
Thermostat
(defrost)
Thermostat is in a series circuit with
terminal 2 of defrost timer, and defrost
heater. Circuit is complete if evaporator
fan motor operates when cold.
Controls the circuit from freezer
thermostat through defrost terminator to
defrost heater. Opens and breaks circuit
when thermostat senses preset high
temperature.
Test continuity across terminals.
With power off and evaporator coil below freezing, thermostat should show
continuity when checked with ohmmeter. See “Heater, evaporator (defrost)”
section for additional tests.
After defrost thermostat opens, thermostat remains open until end of defrost cycle
and refrigerator starts cooling again. Defrost thermostat senses a preset low
temperature and resets (closes).
Thermistor
Temperature sensing device
Check resistance across leads.
Temperature Resistance
25
°
C 10,000 ohms
2.2
°
C 29,500 ohms
-17.7
°
C 86,300 ohms
Condenser motor
Condenser fan moves cooling air across
condenser coil and compressor body.
Condenser fan motor is in parallel circuit
with compressor.
Check resistance across coil.
ECM condenser
motor
Condenser fan moves cooling air across
condenser coil and compressor body.
Condenser fan motor is in parallel circuit
with compressor.
Check resistance across coil.
WARNING
!
To avoid severe personal injury or death from sudden eruption of high
pressures gases, observe the following:
Protect against a sudden eruption if high pressures are required for leak
checking.
Do not use high pressure compressed gases in refrigeration systems
without a reliable pressure regulator and pressure relief valve in the
lines.
