Mazda Training manual — part 294

AIR CONDITIONING
06 - Symptom Troubleshooting

SG06-1

TC070-15-01H

Technician Name

Symptom Troubleshooting [Manual Air Conditioner]


Purpose: After completing this activity, you will be able to diagnose trouble cause by
using Symptom based approach.

What you will need to complete this activity:

Current model vehicle

Workshop Manual or Body Electrical Trouble Shooting Manual

DVOM (Digital Volts/Ohm Meter)

NOTE

The purpose of this activity is to experience symptom troubleshooting to diagnose
logically. Try not to find the defect setting by just guesswork.

NOTE

This activity sheets are designed based on Mazda 3 technical information. It’s
recommended to provide Mazda 3.

AIR CONDITIONING
06 - Symptom Troubleshooting

SG06-2

TC070-15-01H

Troubleshooting Index

No.

TROUBLESHOOTING ITEM

TROUBLESHOOTING ITEM

1

Insufficient air (or no air) blown from
vents

• Problem with each vent and/or duct

2

Amount of air blown from vents does
not change. (Full-auto air conditioner)

• Malfunction in blower system

3

Amount of air blown from vents does
not change. (Manual air conditioner)

• Malfunction in blower system

4

Air intake mode does not change.

• Air intake mode does not change when
switching REC/FRESH mode.

5

No temperature control with climate
control unit

• Malfunction in A/C unit and/or climate control
unit air mix system

6

Windshield fogged.

• A/C compressor does not operate while airflow
mode is in DEFROSTER or HEAT/DEF modes.

7

Air from vents not cold enough

• Magnetic clutch operates but A/C system
malfunctions.

8

No cool air

• Magnetic clutch does not operate.

9

Noise while operating A/C system

• Noise from magnetic clutch, A/C compressor,
hose or refrigerant line

AIR CONDITIONING
06 - Symptom Troubleshooting

SG06-3

TC070-15-01H

8 No cool air (DESCRIPTION: Magnetic clutch does not operate.)

Among the nine troubleshooting items indicated on the previous page, we see the
item No. 8 to learn how to diagnose Air Conditioner.


Preparatory study

As it’s given the description “Magnetic clutch does not operate”, the trouble is with an
electrical/electronic device. See the Magnetic clutch circuit below. The magnetic
clutch is activated when the PCM ground the coil inside the A/C relay to close the
contact of the relay. Magnetic clutch is grounded through its body; an open circuit
between Magnetic clutch and ground is unlikely occurred. If the magnetic clutch
doesn’t operate with battery voltage applied through the A/C relay, the magnetic
clutch may be faulty. Thermal protector inside the Magnetic clutch opens the circuit
when its temperature is approximately 120 ºC or more.

Look at the diagram above; predict the voltage at each terminal given in the table
below during each status.

Status

Part name Terminal

IG switch OFF

IG switch ON

PCM ground the coil

inside A/C relay

A

V

V

V

E

V

V

V

C

V

V

V

A/C relay

D

V

V

V

Magnetic
clutch

A

V

V

V

AIR CONDITIONING
06 - Symptom Troubleshooting

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TC070-15-01H

The figure below describes the A/C Compressor Control. The climate control unit
sends an A/C signal to the PCM via the main fuse block and instrument cluster (PJB
and instrument cluster) based on signals sent from the A/C switch, fan switch and
evaporator temperature sensor.

Chose the correct status or insert an appropriate number to complete the conditions
that the PCM will close the circuit of the A/C relay to supply power activating the
magnetic clutch.

1. A/C switch: ON / OFF.

2. Fan switch: OFF position / Other than OFF position (1, 2, 3, or 4).

3. Evaporator temperature sensor: V or more
(4.5 ºC or more)

4. Refrigerant pressure switch: ON / OFF.

(Between 0.2 and 3.0 MPa)

Service Tip

1. The LED on the A/C switch goes on when the switch is on. This proves the switch

operates properly. However, it doesn’t exactly tell you the climate control unit
receives the signal.

2. If the blower motor activated with the Fan switch turned on, it proves the Fan

switch is working properly.

4. If there is no refrigerant, the Refrigerant pressure switch is off.