Mazda Training manual - part 285

AIR CONDITIONING 
02 - Locating A/C Protection Devices

 

 

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Pressure Relief Valve 
1.  Where is this device located? 
 
 
2.  At what pressure will you expect the pressure relief valve to discharge refrigerant 

to the atmosphere? 

 
 
 
 
 
Instructor Sign-Off: 
Now that you have completed this activity, you should be able to: 

 

locate A/C system protection devices 

 

explain the function of protection devices 

This skill will help you evaluate protection devices for correct operation. 
 
Instructor’s initials:   
 

AIR CONDITIONING 
03 - Conducting a Performance Check

 

 

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Technician Name 
 
CONDUCTING A PERFORMANCE CHECK 
 
Purpose: In this activity, you will diagnose a vehicle’s air conditioning system. 
 
A performance check is the basis of air conditioning diagnosis. All diagnostic routines 
should begin and end with this test to determine if the system is performing to 
specifications. It is thorough and easy to perform. 
 
What you will need to complete this activity: 
 

 

Current model vehicle  

 

Workshop Manual or Body Electrical Trouble Shooting Manual 

 

Thermometer 

 

R-134a Refrigerant Pressure Gauge Set (49 C061 0A0B Gas Charge Set) 

 

Safety Glasses 

 

NOTE 

Humidity and temperature have an effect on the outcome of this test. 

 
Function Check 
 

NOTE 

During the following tests, monitor instrument panel gauges and warning lights for 
out of specification readings. 

 
1.  Set hand brake and place gear selector in Park (ATX) or Neutral (MTX). 
 
2.  Keep hood open throughout the test to maximize airflow through the radiator and 

condenser. 

 
3.  With engine running, select all the blower fan speeds. 

Does the fan speed change? … Yes  … No 
 
Are all speeds available? … Yes  … No 
(If no, repair according to workshop manual directions.) 

 
4.  Operate mode control to all positions and confirm that sufficient airflow is at each 

position. 

Does the airflow change according to the position of the mode control indication 
on the dash? … Yes  … No 
(If no, repair according to workshop manual directions.) 

 

AIR CONDITIONING 
03 - Conducting a Performance Check

 

 

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5. Operate temperature select control throughout its range and confirm that the 

airflow temperature matches the setting. Start with the control in the coolest 
setting and slowly increase temperature to highest setting, then back to original 
setting. Does the temperature match the control setting? … Yes  … No 

(If no, repair according to workshop manual directions.) 

 
6.  Turn off engine. 
 

INFORMATION POINT 

A small temperature difference between the setting and the actual duct 
temperature is normal. The duct temperature will usually be cooler than the interior 
temperature. This is because the evaporator is concentrated in the small area of 
the duct very close to the evaporator. 

 
 
Gauge Installation 

Install R-134a Refrigerant Pressure Gauge Set according to the workshop manual. 
 

a.  Confirm that high and low valves are closed. 
b.  Remove caps from charging ports. 
c.  Connect the quick disconnect couples to vehicle charging ports and open line 

valves. 

 

NOTE 

Support A/C lines during coupling. Excessive pressure can cause damage to 
unsupported lines. 

 
 
Refrigerant Pressure Check 
 
2.  Place a dry-bulb thermometer in the driver-side center ventilator outlet. 
 
3.  Close all doors and windows. 
 
4.  Set A/C controls for maximum cooling with: 
  

a.  temperature to full cold 
b.  airflow to face/vent to Vent 
c.  fresh/recirculate control to Recirculate 
d.  activate compressor with fan speed high 
 

5.  Start engine and hold at 1,500 rpm.  
 
 
 

AIR CONDITIONING 
03 - Conducting a Performance Check

 

 

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6.  Measure the ambient temperature and high- and low- pressure side reading of the 

pressure gauge.  

 

Ambient temperature                        °C 
 
High pressure                       psi   /     Low pressure                        psi                 
Ambient temperature                    

 
 
7.  Verify that the intersection of the pressure reading of the pressure gauge and 

ambient temperature is in the shaded zone.  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Performance Check 
 
1.  Place a dry-bulb thermometer in the driver-side center ventilator outlet. 
 
2.  Close all doors and windows. 
 
3.  Set A/C controls for maximum cooling with: 
  

a.  temperature to full cold 
b.  airflow to face/vent to Vent 
c.  fresh/recirculate control to Recirculate 
d.  activate compressor with fan speed high