TrailerAC

Question 1

What is conduction heat

Answer 1

Heat movement through solids

Question 2

What is convection heat

Answer 2

Heat movement through fluids

Question 3

How many BTU does it take to raise 1 pound of water 1 degree f

Answer 3

1 BTU = 1055 joules

Question 4

Perfect vacuum reading

Answer 4

29.9hg

Question 5

Stages of refrigeration

Answer 5

Compress, condense, expand, evaporate.

Question 6

What state is compressor suction and discharge

Answer 6

Low side vapour suction
High side vapour discharge

Question 7

How to isolate the compressor

Answer 7

Stem valve Front seated

Back seated is normal operation

Question 8

What is the air gap the clutch should be shimmed too

Answer 8

.020-.030

Question 9

Purpose of the condenser

Answer 9

Turn high pressure vapour from the compressor to low pressure liquid

Question 10

Symptom of condenser not performing

Answer 10

Frosting
Can’t absorb heat .
No air flow
Internal restriction

Question 11

What is the appropriate temp difference on inlet and outlet of the condenser

Answer 11

Good 20-40
Over 40 bad- restriction
Under 20 bad - poor air flow

Question 12

What side is the dryer on

Answer 12

High side

Question 13

What does the dryer do

Answer 13

Removes moisture 14ppm is bad

Question 14

Most common TXV failure caused by

Answer 14

Moisture

Question 15

TXV stuck open would cause

Answer 15

Flood the evap causing freezing

Question 16

What does the bionary system not have

Answer 16

Fan control

Question 17

Ac system with fixed orifice

Answer 17

Not variable , same size

Question 18

How does trailer air recirculate

Answer 18

Ribbed floor

Question 19

What bias is the 3 way valve

Answer 19

Normally bias to cold

Question 20

What does the throttling valve do

Answer 20

Regulates refrigerant entering the compressor

Question 21

What is the pilot solenoid

Answer 21

A normally closed contact causes 3 way valve to switch from cool to heat when energized

Question 22

The difference of the trailer TXV

Answer 22

Adjustable , has an equalizer valve

Question 23

When testing pressure what is common for internal leak reading

Answer 23

Pressures rises past 0hg to positive pressure

Question 24

Affects of loose trailer temp bulb

Answer 24

It will default to detect heat and open the TXV

Question 25

Trailer ac
High side pressure (head pressure)
Causes

Answer 25

Restriction in high side line
Lack of air movement
TXV adjusted to small
Air in system
Overcharged

Question 26

Low high side pressure
Causes

Answer 26

Cold ambient temp
Wrong refrigerant
Low charge
Worn out compressor
Low side restriction

Question 27

Non mechanical cooling problems

Answer 27

Air leaks
Bad door seals
Warm product
Belt slippage

Question 28

Causes for low pressure on both sides

Answer 28

Low refrigerant
Lots of bubbles in sight glass

Question 29

What would symptoms be with air in system

Answer 29

Poor performance
Fluctuating gauges
Bubbles in sight glass

Question 30

Symptoms with a high side restriction at the dryer

Answer 30

High pressure on high side
Low pressure on low side
Frosting on lines

Question 31

Symptoms of a line blockage

Answer 31

Frost on line
Both sides read 0
Both sides of dryer are warm

Question 32

Symptoms of an overcharged system

Answer 32

Both sides reading high
Frost on suction line
Poor performance

Question 33

High side components

Answer 33

Compressor discharge
Condenser
Dryer

Question 34

Low side components

Answer 34

TXV
Evap coil
Heat exchanger
Compressor suction

Question 35

Frosted lines causes

Answer 35

Low air flow , restrictions , not changing states

Question 36

What is the accumulator

Answer 36

Accumulates liquid and allows for refrigerant to vaporize before entering the compressor

Question 37

Trailer refrigerant

Answer 37

R-402

Question 38

What component is the 3 way valve bias too

Answer 38

Condenser

Question 39

AC gauge hook ups

Answer 39

Pressure check
Both closed

Vapour charging
Low open high closed

Liquid charging
Low closed high open