Troubleshooting package-type air-conditioning units(PACU) / commercial refrigeration equipment (CRE)

4. Bring the nozzle up in a vertical angle with the fins and then cross 2.54
cm. Bring the nozzle down and repeat the up and down movement of the
spray.

5. Keep repeating the spraying pattern until the entire coil is covered.
6. If the compressed air, soap and water spray fail to thoroughly clean the

evaporator a portable steam cleaner may be used. The steam set should
be sprayed w/ the same technique as the compressed gas soap and water
cleaning. The fins maybe bent slightly bent they can be easily straightened
w/ fin comb.

Steps in using Portable Steam Cleaner

1. open gate valve of water source by turning counter clockwise as shown
2. Plug in steam cleaner to run motor and pump as shown
3. Unscrew panel threat covers the evaporator
4. Point the nozzle of the steam to the evaporator and press switch to bring

out the steam
5. Slowly move the nozzle upward and downward moving sideways to other

fins until the evaporator area is cleaned

Straightening Bent fins

1. Insert fin comb to the bent fins
2. Press the fin comb slightly until you see that bends are already straight.
3. Repeat slip one and two until bent fins are straightened

Job Sheet Cleaning a Condenser

Tools and materials
1. PACU/CRE unit
2. Plastic bag
3. Soap
4. Water hose
5. Spray nozzle

Procedure
1. Remove all panel cover
2. Wrap the fan motor w/ plastic bag
3. Remove screw that hold the condenser to fan should
4. Spray water w/ soap into the condenser
5. Brush fins using appropriate brush
6. Attach water hose to hydrant
7. Attach spray nozzle
8. Spray condenser w/ water
9. Tilt condenser sideways so that water will run out
10. Remove plastic bag from motor
11. Dry all electrical components w/ shop towel
12. Carefully move condenser back into proper position
13. Replace the screw w/ hold the condenser to the should
14. Straightened fins w/ fin comb
15. Have the instructor check your job
16. Clean up and put away tools and instrument

Self Check
Call your instructor who will observed you clean remove or replace an evarator
as well as straightened the bent fins of an evaporator

Instructor Checklist Acceptability
Yes No

1. Selection and preparation of tools to be used
2. Choice of method to be followed
3. Setting up of the workplace
4. Preparation of the workplace
5. Quality of brazed portion or wildments- is it leak proof
6. Thoroughness in cleaning finned evaporators
7. Quality of repaired bent fins is it straight enough after the repair
8. Observed of safety precautions

Job Sheet

Troubleshoot Circuit for Open Connection or
Loose Connection

Objectives: At the end of this activity, the learner/trainee should be able to:
o Locate cause of trouble which causes compressor to operate in

short cycle.
o Restore PACU/CRE to normal operation
o Apply safety and proper work habit

Materials, Tools and Equipment:

Materials: - 1 set
o Electrical diagram
- 1 set
Tools - 1 unit
o Screw driver
o Wrench

Instrument
o Multi-tester

- Item is optional-

Introduction:
.

Job Sheet

Procedure:
Make sure that before you perform this activity, you are wearing appropriate personal

protective equipment.

1. Based from the diagram analyze Control Circuit
the circuit, determine the
components and connection that
belongs to the control circuit and
power circuit for the compressor
motor.

Power Circuit

Job Sheet

2. There is no general rule on which
circuit is to be troubleshoot first
how ever there is a concept that
the more power the circuit
consumes, greater amount of
work it performs, the higher the
risk of it being worn-out.
Therefore for discussion purpose
we are going to start with the
power circuit.

3. Analyze the components and
connection of the power circuit
for the compressor motor.

You can clearly see that the
power circuit is composed of
three conductor lines connected
to Line 1, Line 2 and Line 3,
overload control relay sensing
element (OC),Magnetic switch
(MS 2) and the terminal of the
compressor motor.

If you were to analyze the circuit,
from line terminal to the
compressor motor terminal, the
signal will flow to the wires
connected to L1, L2 and L3,
going to the terminal of the
overload control sensing
element, then going to magnetic
switch contact, then electrical
wires again connected to the
terminal of the compressor
motor. Therefore you can
assume that the reason why the
supply signal does not reach the
terminal of the compressor is
because there is an loose wiring,
open wiring, defective circuit
breaker or defective control
circuit that disables the magnetic
switch (MS2).

4.

Job Sheet

1. Ask your instructor on the unit to be used for this activity.
2. Analyze the attached chart to this activity. Follow the instruction in each process box

until such time that you repaired the air-conditioning unit assigned to you. You may
use several learning elements and learning module identified in this activity as your
reference in performing the required activity.
3. Let your instructor check your work.
4. Perform proper house keeping

Job Sheet

Trouble: Compressor operate in short cycle
Observable Symptoms:

 Low cooling effect
 Frosting evaporator

Start

Check if there are restrictions Restricted evaporating unit may cause
in the air flow in the evaporator refrigeration and air conditioning to have
low cooling effect because there is no
unit complete evaporation of refrigerant
(Refer to learning element in evaporator
Is there any and condenser unit).
restriction?
Clean evaporator unit 1
or remove any

restriction to the air
flow

1 Check evaporator fan Defective evaporator fan will have the
motor same effect with restricted air flow in the
condensing unit (Refer to learning
Maintain/ Repair/ element about fan motors)
Replace evaporator
2
motor

Does evaporator If the air flow is not restricted Recover/ recycle
fan motor require and the fan motor is Refrigerant
functioning properly, the
maintenance/ most probable cause of the Change Filter
repair/ system not cooling is a
contaminated refrigerant Evacuate the system
replacement? (Refer to learning module
about recover recycle, Re-charge the system
2 Test run the unit learning element in
refrigeration accessories,
Did the unit tools equipment used in
function refrigeration and air
properly? conditioning services and
charging PACU/CRE) .

2

Stop

Job Sheet

Evaluation:
While performing the activity it is important for you to assess your performance

following the criteria below:

Operation Sheet

Circuit Tracing

Objectives: At the end of this activity, the learner/trainee should be able to:
o Locate the open component in the given circuit
o Restore the circuit into proper operation
o Apply safety and proper work habit

Materials, Tools and Equipment:

Materials: - 1 set
o Replacement component - 1 unit
o Electrical diagram - 1 unit

Instrument
o Multi-tester

Equipment
o Circuit trainer for open connection

- Item is optional-

Introduction:
.

Based on the diagram analyze the
circuit, determine the path of electrical
current.

As you can se, all the
components are connected in series,
therefore any open, loose or defective
component may cause for the load not
to light.

If in case the load does not lit,
you may suspect that the signal from
L2 does not reach the load or the
signal from Line 1 does not reach the
load. Your job now as a service
technician is to actually pinpoint the
location of the trouble and make the
necessary action to remedy the fault.

Operation Sheet

Procedure:
Make sure that before you perform this activity, you are wearing appropriate personal

protective equipment.

1. DISCONNECT THE CIRCUIT
FROM THE POWER
SOURCE. Failure to do so may
damage the ohmmeter.

2. Measure the resistance of the
load. This is to verify if the load
is in good condition

Load =____________ Ω

Q1. Is the load in good
condition? Why?
___________________
___________________
___________________
___________________
___________________

If the load is in good condition
there is no need to proceed to
the next step, but if it is not,
proceed to step 3.

3. Measure the resistance of the
circuit across L1 and L2.
a. L1 = ____________Ω

Operation Sheet

b. L2 = ____________ Ω

Q2. What line do you think is
defective? Why?
____________________
____________________
____________________
____________________
____________________
____________________
____________________

If line 1 is defective
A. Measure the resistance of each
component located at line 1.
This is to verify the continuity of
the signal through the
component.

c. SW 1, open position
=___________ Ω

Operation Sheet

d. SW1, closed position
=_____________ Ω

e. F1 =_____________ Ω

f. R1 =_____________ Ω

Q3. Did you find any defective
component? _________

If yes…

Operation Sheet

Q4. What component do you
think is defective? Why?
____________________
____________________
____________________
____________________
____________________

Replace the defective
component and test the
unit. If it function let your
instructor check your work,
if proceed to step B.
If no …..
Proceed to step B.

B. Check wiring connection as
illustrated in the diagram

a. across point A and B =
_________Ω

b. across point C and D =
________Ω

Operation Sheet

c. across point E and F =
________Ω

d. across point G and H =
________Ω

Q5. What point of the circuit is
open? _________

Q6. Why do you say so?
____________________
____________________
____________________
____________________
____________________

After repairing the
defective connection let
your instructor check your
work.

If line 2 is defective
C. Measure the resistance of each
component located at line 2.
This is to verify the continuity of
the signal through the
component.

Operation Sheet

a. SW 2, open position
=___________ Ω

b. SW2, closed position
=_____________ Ω

c. F2 =_____________ Ω

Operation Sheet

d. R2 =_____________ Ω

Q1. Did you find any defective
component? _________

If yes…

Q2. What component do you
think is defective? Why?
____________________
____________________
____________________
____________________
____________________

Replace the defective
component and test the
unit. If it function let your
instructor check your work,
if proceed to step D.

If no …..
Proceed to step D.

D. Check wiring connection as
illustrated in the diagram

Operation Sheet

a. across point I and J =
_________Ω

b. across point K and L =
________Ω

c. across point M and N =
________Ω

d. across point O and P =
________Ω

Q5. What point of the circuit is
open? _________

Operation Sheet

Q6. Why do you say so?
____________________
____________________
____________________
____________________
____________________

After repairing the
defective connection let
your instructor check your
work.

Evaluation:

While performing the activity it is important for you to assess your performance
following the criteria below:

 defective component is pinpointed using an ohmmeter
 defects are remedied
 unit is restored to proper operation

Information Sheet 1

Electrical Controls: Current and Potential Relays

1. As the motor runs, the control bulb is Relay – current type
cooled and the pressure in the bellows
is reduced. The reduction of pressure
allows the spring to push the bimetal in
opposite directions, snapping the switch
and stopping the motor. The control
bulb slowly warms up until the motor
starts again and the cycle is repeated.

Current relays and magnetic switches
are generally used on low torque
smaller (H.P.) motors. Shown below is
the diagram of a current relay switch.

Shown below is a diagram of current relay and magnetic switch connection.

Current Relay Connection

Information Sheet 1

1. Current relay and magnetic switch are
normally open, as shown.

2. This normally open contact closes
immediately when the motor is energized
by the surge of current which occurs at the
time of starting (see illustration at right).

3. When the motor speeds up, the current drops and the magnetic coil which is in the main
winding circuit releases the movable contact, disconnecting the starting winding, as
shown.

Information Sheet 1

4. POTENTIAL RELAYS are generally used on high torque capacitor motors. Shown below
is diagram of the parts of a potential relay.

Parts of Potential Relay
POTENTIAL RELAY CONNECTIONS
High starting torque motors 2 terminal overload potential relay

Information Sheet 1

1. The contacts are normally closed, as
shown.

2. The coil is continuously connected to the
starting winding, as shown.

3. The coil opens the starting contact when a
predetermined voltage appears across it,
as shown.

4. The contacts remain open during normal
operation, due to the induced start winding
voltage, as shown.

Information Sheet 1

5. Contact closes when the voltage across it
is cut or stopped.

Self-Check 1

Electrical Controls: Current and Potential Relays

Direction: Read the items carefully and answer each question correctly. Write only the letters
on the space provided.

_____ 1. The function of which is to disconnect the motor from the source when the motor
becomes overloaded
a. pressure control
b. thermostat
c. temperature control
d. overload protector

_____ 2. Which one is NOT an electric control?
a. float switches
b. relays
c. capacitor
d. thermostat

_____ 3. An automatic switching device that disconnects the starting winding after reaching
its three-fourth rated speed is called
a. relay
b. overload
c. thermostat
d. running capacitor

_____ 4. A relay generally used on low torque smaller H.P. motor.
a. potential
b. current
c. pilot
d. capacitor

_____ 5. A winding of the motor that is disconnected when the motor has reached its
equivalent value
a. running
b. common
c. starting
d. secondary

Self-Check 1

_____ 6. Current and potential relays have similarities except in
a. overload
b. compressor terminals
c. control
d. motor capacity

_____ 7. When the motor resumes its normal operation, this winding is the only one
connected to the circuit.
a. starting
b. running
c. secondary
d. common

_____ 8. A type of relay generally used on a high torque capacitor motor.
a. potential
b. current
c. pilot
d. hot wire

Answer Key 1

Electrical Controls: Current and Potential Relays

1. d
2. c
3. a
4. b
5. c
6. d
7. b
8. a

Operation Sheet 1

Checking Current Relay (Coil type)

Objectives: At the end of this practice the learner/trainee will be able to:

o Identify defective relay contacts.
o Follow steps in checking current relays.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration Unit
- 1 pc
Materials:
o Current relay, coil type - 1 pc
1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers - 1 unit
o Diagonal cutting pliers
o Multimeter - 1 pair
- 1 pc
Personal Protective Equipment:
o Gloves
o Goggles

Operation Sheet 1

Procedures:

1. Unplug the unit.

2. Disconnect wiring connection of
current relay and remove it to from the
compressor.

3. Set the multimeter to Rx100 and
calibrate the meter through zero ohm
adjust knob.

4. Place the test prods of the meter to L
and M terminals of the current relay.

5. Hold the current relay in upside down
position.

Operation Sheet 1

6. Observe the deflection of the meter
pointer.

Note: If the ohmmeter reads
approximately 1 ohm, the relay is
good, if the pointer did not deflect,
the current relay is open.

7. Now place the test prods of the meter
to L and S terminals of the current
relay while the relay is in upside down
position

Note: If the pointer did not deflect,
the relay contact is open as it
should be, but if it has low
resistance reading, the contacts are
stuck-up and therefore defective.

8. Transfer the test prods on M and S
terminal. Still in upside down position.
Note: If the ohmmeter reads a low
resistance, the contacts are close
(good), but if the pointer did not
deflect, contacts are not closing
properly.

9. Have your instructor check your work.

10. Perform housekeeping.

Operation Sheet 2

Checking Potential Relay (Voltage Relay)

Objectives: At the end of this practice the learner/trainee will be able to:

o Identify defective potential relay using multimeter
o Follow steps in checking potential relay.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration Unit
- 1 pc
Materials:
o Potential Relay - 1 pc
1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers
o Diagonal cutting pliers - 1 pair
- 1 pc
Personal Protective Equipment:
o Gloves
o Goggles

Operation Sheet 2

Procedures:

1. Unplug the unit.

2. Disconnect wiring connection from potential
relay and remove it from the compressor.

3. Set the multimeter to Rx100 and calibrate
the meter through zero ohm adjust knob.

4. Place the test prods of the meter to #5 and
#2 terminals of the potential relay.

5. Observe the deflection of the meter pointer.
Note: If the ohmmeter reads a resistance,
the relay coil is good. If the pointer did
not deflect, the coil is open.

6. Now place the test prods of the meter to #1
and #2 terminals of the potential relay.
Note: If the ohmmeter reads a low
resistance, the contacts are close (good),
but if the pointer did not deflect, contacts
are open and it is defective.

7. Have your instructor check your work.

8. Perform housekeeping.

Operation Sheet

Replacing Circuit Breaker

Objectives: At the end of this activity, the learner/trainee should be able to:
o Check condition of circuit breaker
o Replace circuit breaker
o Demonstrate safety practices in checking and replacing circuit

breaker

Materials, Tools and Equipment:

Materials: - 1 set
o Replacement circuit breaker
- 1 pc
Tools - 1 pc
o Insulated side cutter
o Insulated pliers - 1 unit

Instrument
o Multitester

* - Item is optional

Introduction:

Circuit breaker is protective device that cuts the supply line in case of trouble in the
system. Below is a procedure in resetting, testing and replacing circuit breaker.

Procedure:
Make sure that before you perform this activity, you are wearing appropriate personal

protective equipment.
1. Open the control box

Operation Sheet

2. To determine if the circuit breaker
tripped, you can observe its lever. If
the lever is in mid position (and it is
slightly loose when moved) it means
that the circuit breaker has tripped. It
can be verified by measuring the
voltage after it passes the circuit
breaker. Lower voltage than the
expected normal voltage, denotes
that it has tripped.

3. If the circuit breaker tripped, check
the load side for short circuit first
before resetting it. If there is a short
in the circuit, troubleshoot it first
before resetting the circuit breaker,
otherwise it will trip again. This may
inflict further trouble to the circuit.

4. If you are sure that there is no short
in the circuit, you can now switch it
ON

5. Monitor the supply in the load side. In
case there is still no power in the
circuit, but you are sure that there is
power in the source line, replace the
circuit breaker.

To replace the circuit breaker
1. Remove wires at the load side of the
circuit breaker

Operation Sheet

2. Remove the wire at the line side of
the circuit breaker. Remove wire one
at a time to prevent the wire from
rubbing to each other especially if it
is live. Cut the bare conductor or
insulate it with a tape.

3. Remove the defective circuit breaker
and install the new one with the
same rating.

4. Strip the wire at the load side

5. Connect the wire into the circuit
breaker terminal

Operation Sheet

6. Strip the wire at the source line.
Make sure you do it one by one to
prevent it from rubbing to each other
which may cause line explosion if the
wire is live.

7. Connect the wire at the terminal of
the circuit breaker. Make sure that
you tighten

8. Switch on the breaker and test the
supply at the load side. Refer to
troubleshooting guide if trouble
arises

Operation Sheet

9. Install the box cover.

Evaluation:

While performing the activity it is important for you to assess your performance
following the criteria below:

 The condition of circuit breaker is checked following prescribed procedure
 Circuit is ensured to be short free before resetting the new circuit breaker
 Circuit breaker is replaced with the same rating as the original
 Defective circuit breaker is replaced following prescribed procedure and standard
 Safety and proper housekeeping is employed during the activity.

Replacing Fuse

1. Switch-off the control
2. Open the fuse box
3. Check the load side of the control for short circuit. If there is a short in the

circuit, troubleshoot it first before replacing the fuse, otherwise the new
fuse will blow again
4. using an isolated pliers, remove and replace the new fuse
5. Switch the control box and monitor the voltage refer to troubleshooting
guide if trouble arises

Replacing circuit breaker

1. Open the control box
2. Remove the circuit breaker
3. Check the load side for short circuit. If there is a short in the circuit,

troubleshoot it first before replacing the fuse, otherwise the new circuit
breaker will trip again.
4. Install the new circuit breaker and monitor the supply. Refer to
troubleshooting guide if trouble arises

Checking of fuse or circuit breaker
1. Check power at the line side

2. Check the power at the load side

Note: If the power could be measured from the circuit above, one both the
protection device is busted or has tripped of a circuit breaker that
tripped can easily be noticed.

However for the fuse type protection, further testing should be done to identify
which fuse is defective.

Testing circuit breaker

1. Remove the circuit breaker from the box/panel and make sure that there is
no electrical wire connected to it.

2. Switch on the circuit breaker
3. Test the continuity of the circuit breaker

Indication of good circuit breaker contact
a. When the circuit breaker is switched on the meter reading should be

zeroΩ
b. When the circuit breaker is switched off, the meter reading should be

infinite since the contact is open

4. To test weather mechanical part of the circuit breaker will trip when short
in the circuit is sensed:

a. Switched on the circuit breaker
b. Hold the CB on the side tightly

Job Sheet

Remove and replace condenser fan motor
Objective: At the end of this practice the learner/trainee will be able to:

 Remove and replace condenser fan motor
 Use proper tools in remaining fan motor
 Re-start the operation of condenser fan motor

Materials: 1-unit
 Fan motor 1-pcs
 Electrical tape 2-pcs
 Rags 1-pair
 Gloves

Tools:

 Philips screw driver 1-set
 Flat screw driver 1-set
 Allen wrench 1-set
 Long nose 1-pcs
 Adjustable wrench 1-pcs

Testing Instruments: 1-unit
 Clamp 1-unit
 VOM

Equipment:

Procedures:
1. Turn off the power of a unit, check with a VOM and tag the
electrical panel.
2. Remove the condenser fan motor panel.
3. Make a wiring diagram for the fan motor connections or mark for
every terminal.
4. Discharge fan capacitor, and disconnect the motor terminal.
5. if the motor is direct drive, remove the motor from the compartment.
6. Replace new condenser fan motor.
7. Re-connect the wiring connections.
8. Double check the wiring.
9. Start the motor, check the proper rotation and running current.
10. Turn the condenser fan motor off and return the condenser fan
motor panel.

Operation Sheet

Replacing Fuse

Objectives: At the end of this activity, the learner/trainee should be able to:
o Check condition of fuse
o Replace fuse
o Demonstrate safety practices in checking and replacing fuse

Materials, Tools and Equipment:

Materials: - 2 pc
o Replacement fuse - 1 set
- 1 unit
Tools
o Insulated pliers

Instrument
o Multitester

* - Item is optional

Introduction:

Fuses are protective device that cuts the supply line in case of trouble in the system.
Below is a procedure in testing and replacing fuse.

Procedure:
Make sure that before you perform this activity, you are wearing appropriate personal

protective equipment.
1. Open the fuse box

Operation Sheet

2. To verify if there is supply in the line
side, place the test probe of your
voltmeter in the line side.

3. To determine if a fuse is busted,
place the test probe of your voltmeter
at the load side of the fuse. If the
meter reading is below than the
expected normal voltage it denotes
that fuse is busted.

4. To determine which of the fuse is
busted place the test probe across
each fuse.

You can see from the figure above that
there is a voltage reading across fuse B and
line 1. This means that the electrical signal
can pass through fuse B. Therefore the fuse

is in good condition.

Operation Sheet

You can see from the figure above that
there is a voltage reading across fuse A and
line 2. This means that the electrical signal
can pass through fuse A. Therefore the fuse

is in good condition.

In the figure above you can see that there
no voltage reading across line 1 and fuse B.

The reason is that fuse B is busted.
Therefore the electrical signal cannot pass

through fuse B.

Operation Sheet

5. In case a fuse is busted, switch off
the circuit then check the load side of
the fuse for short circuit. If there is a
short in the circuit, troubleshoot it first
before replacing the fuse, otherwise
the new fuse will blow again

6. Using an isolated pliers, remove and
replace the new fuse with the same
rating. DO NOT PLACE A JUMPER
WIRE IN REPLACEMENT TO FUSE.
A jumper wire might not blow in case
of short circuit.

7. Switch on the control box and
monitor the voltage refer to
troubleshooting guide if trouble
arises

8. Dispose the busted fuse properly

Operation Sheet

Evaluation:

While performing the activity it is important for you to assess your performance
following the criteria below:

 The condition of fuse is checked following prescribed procedure
 Circuit is ensured to be short free before installing new fuse
 Fuse is replaced with the same rating as the original
 Busted fuse is replaced following prescribed procedure and standard
 Safety and proper housekeeping is employed during the activity.

Job Sheet

Tracing out Short Circuit

Objectives: At the end of this activity, the learner/trainee should be able to:
o Isolate the different electrical section of the refrigeration or air

conditioning unit
o Trace the source of short in the circuit
o Repair short circuit
o Prepare job report
o Demonstrate safety practices while working

Materials, Tools and Equipment:

Materials: - 1 set
o Units wiring diagram - 1 pc
o Replacement component - 1 pc

Tools - 1 unit
o Insulated side cutter
o Insulated pliers
o Screw drivers

Instrument
o Multitester

* - Item is optional

Introduction:

Short in the circuit draws large amount of current making the circuit protector cut
power in the circuit to prevent further damage to the unit. A technique in pin pointing the
location of short in the circuit is discussed below

Procedure:
Make sure that before you perform this activity, you are wearing appropriate personal

protective equipment.
1. Disconnect the power source by
turning off the main circuit breaker.

2. Isolate the three major electrical
circuits (condenser fan motor circuit,
compressor motor circuit and
evaporator fan motor circuit) from
each other.