Refrigerators

Question 1

What are the three purposes of the P-trap on the sealed combustion fridges?

Answer 1

Prevent down draft
Prevent moisture from outside
Prevent condensation from dripping on the flame

Question 2

What is a sealed combustion fridge?

Answer 2

A fridge that draws combustion air from outside and exhausts outside the unit

Question 3

What is the priority sequence for a norcold fridge?

Answer 3

1st- AC
2nd- propane
3rd- 12vdc

Question 4

What is the priority sequence for a domestic fridge

Answer 4

1- AC
2- 12VDC
3-propane

Question 5

What should you do with a fridge door that is cracked or warped?

Answer 5

Replace

Question 6

What is the advantage of wire shelving in the fridge?

Answer 6

Allows for good air flow and circulation

Question 7

How do you adjust a fridge door?

Answer 7

Loosen the hinge bracket screw and adjust.

All or remove washers if need to raise or lower the door

Question 8

How might the light be wired into the fridge?

Answer 8

May be wired into the harness for the thermistor

Question 9

What turns the fridge light on in low ambient temp.

And what temp should it turn off?

Answer 9

Low ambient temp switch

Should turn off when it’s 50F (10C) outside

Question 10

What can happen if the door switch is defective?

Answer 10

It can cause inefficient cooling if the bulb remains on

Question 11

What should be turned on if condensation is noticed

Answer 11

The High humidity switch and heater

Question 12

What does the High humidity and heater do?

Answer 12

Keeps the surface between the door opening dry during high humidity conditions

Question 13

What are two purposes of the eyebrow control

Answer 13

Used to select the mode of operation

Displays the mode of operation

Question 14

What senses refrigerator interior temp.

Answer 14

Thermistor

Question 15

What will temp do to the thermistor?

Answer 15

It affects the resistance of the thermistor
Temp increases - resistance decreases
Temp decrease- resistance increases

Question 16

What 3 components will distribute DC Current?

Answer 16

Connecting lead,
Ribbon cables
Wire harnesses

Question 17

What controls the circuit to the 12vdc heat element?

Answer 17

The 12vdc relay

Question 18

What completes the circuit through the flame to ground?

Answer 18

The sensor probe

Question 19

What does the ignition module do?

Answer 19

Ignited and monitors the flame
Powers the gas valve
If flame is out it will spark for a period, the close the gas valve and go into “check” mode

Question 20

What does the reignitor/relighted do?

Answer 20

• Monitors the flow of micro-amps through the flame.

- If it doesn’t sense micro-amps it will spark indefinitely until flame is established

Question 21

How far must the igniter probe or electrode be above the burner

Answer 21

Domestic: 3/16 above burner
Norcold: 1/8”-3/16 above burner slots

Question 22

What is a zip tube?

Answer 22

A perforated aluminum tube with holes that allows the flame to travel down

Question 23

What should you do if the piezo snaps but there is no spark?

Answer 23

There is a problem with the high tension wire or the electrode

Question 24

What does the thermocouple do and what does it generate

Answer 24

It energizes the electromagnetic in the safety valve

Generates 14-30 Millivolts

Question 25

When should you replace the thermocouple?

Answer 25

If the tip is burnt.

Question 26

What are the two types of electric heating elements?

Answer 26

Pencil type | Cartridge type

Question 27

How big is the cartridge type heating element?

Answer 27

5/8” or larger

Question 28

Which T-stat has one capillary tube and bellow that controls both functions?

Answer 28

The combination propane/electric thermostat (manual model)

Question 29

What is the purpose of the flue baffle?

Answer 29

It’s to concentrated heat from the burner at the boiler/generator Forces heat to the outside of the flue tube

Question 30

What is directly under the flue tube? | And what is it’s purpose?

Answer 30

The burner | To apply heat to the boiler/generator

Question 31

What are the 4 types of orifices?

Answer 31

- Ceramic insert - drilled brass fitting - stainless steal insert/ brass fitting - laser drilled ruby insert/brass fitting

Question 32

How do you clean all the orifices?

Answer 32

Methal hydrate and tooth pick except the ruby just clean and dry

Question 33

What is threads on most test ports?

Answer 33

1/8” NTP female threads

Question 34

What are the two types of thermostat inlet and outlet fittings? What must be done every time the thermostat is separated?

Answer 34

Threaded type O-ring deal type The o-ring must be replaced

Question 35

What controls the “low flame”? | And what does it consist of?

Answer 35

The bypass screw. | Bypass screw, gasket, o-ring

Question 36

What is in the capillary tube? And what does it do? Where is the sensing side attached too?

Answer 36

Contains refrigerant that expands and contracts It moves the bellows and controls the propane It’s attached to the high-temp evaporator fins

Question 37

On a propane T-stat, what happens when it’s satisfied with the temp.?

Answer 37

The pressure is reduced to 3-5”WC to produce “low flame”

Question 38

What the AC working range of a fridge?

Answer 38

108-132volt

Question 39

What are the 3 functions of the lower vent

Answer 39

Fresh air intake Fresh air for ventilation Access for service

Question 40

Where must the lower fridge vent be?

Answer 40

Bottom edge must be at or below the fridge cabinet floor to allow for propane vapour to flow out

Question 41

What is the “thermo-siphon effect”

Answer 41

Hot air rises and cooler air is drawn in the bottom

Question 42

What is the side clearance for the fridge?

Answer 42

MAX 1/2” on either side

Question 43

What is the max clearance for the top of the fridge?

Answer 43

MAX 1/4”

Question 44

What may may happen to the fridge in low ambient temp

Answer 44

Ammonia/water mixture may gel in the absorber and stop circulating causing the fridge to stop cooling

Question 45

What do you do when performing a Bypass test? | What should it cool to?

Answer 45

You bypass the thermostatic controls and let run for 24 hrs on 120vac Water should cool too -10C

Question 46

What do you do when performing a “run test” | What temp should it cool too

Answer 46

Just let run for 12-24 hours. | Water should cool down too minimum of 6C (43F). (34-38 is better)

Question 47

What does excess moisture or frost build up in the fridge/freezer indicate?

Answer 47

Air leaks

Question 48

What is the hydrogen static gas pressure? And when heated?

Answer 48

250 psi and up to 600psi when heated

Question 49

What are the four main components of the cooling unit

Answer 49

- boiler/generator - condenser - evaporator - absorber vessel/leveling chamber

Question 50

How far off level can the fridge be?

Answer 50

3 degrees side to side | 6 degrees front to back

Question 51

What can happen if the fridge is run off level?

Answer 51

The sodium chromate can overheat and crystallize and cause a blockage

Question 52

What are the 4 chemicals in the cooling units

Answer 52

Ammonia Water Hydrogen Sodium chromate

Question 53

What kinda motor is in the compressor refrigerators?

Answer 53

A “Swing motor”

Question 54

What kind of power do most compressor fridges need at the compressor? How is this accomplished?

Answer 54

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