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Air Conditioning System Service Procedure (AC93-003)

Publication date: 1970-01-01
Reference number: AC93-003

AIR CONDITIONING SYSTEM SERVICE PROCEDURE

AIR CONDITIONING SYSTEM SERVICE PROCEDURE

TECHNICAL SERVICE BULLETIN

Reference Number(s): AC93-003
COPYRIGHT: © 2018 Toyota, USA License Agreement TMS1002

AIR CONDITIONING SYSTEM SERVICE

Model(s): All Toyota Models

Reference: Heating & Air Conditioning

Bulletin No.: AC93-003

Date: March 26, 1993

SERVICE INFORMATION

In recent years, there has been a growing concern for the effects of chemical substances on the environment throughout the world. One of the substances that has attracted attention is the R-12 refrigerant used in automotive air conditioning (A/C) systems.

The chemical name for R-12 is Chlorofluorocarbon (CFC) and it has been identified along with CFC's from other sources as being a contributing factor in the depletion of the ozone layer in the earth's atmosphere as illustrated in Fig 1. The ozone layer provides protection from the harmful effects of the sun's ultraviolet rays. Consequently, it is very important to minimize the amount of refrigerant released into the atmosphere.

Fig 1: Ozone Layer Depletion
G93G56446Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

When servicing the A/C system it is mandatory to use a Toyota Approved R-12 refrigerant recovery machine (Toyota P/N 00002-01396-01) or its equivalent, and to use only the minimum amount of refrigerant necessary to test or charge the system. See Fig 2.

Fig 2: Refrigerant Recovery Machine
G93H56447Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The actual repair of each model's A/C system is detailed in the appropriate Toyota publications. However, to aid you in making quick, accurate diagnosis and repair of low refrigerant level conditions, the following inspection procedures have been developed.

QUICK CHECKS OF REFRIGERANT VOLUME

Inspect the condition of the refrigerant flowing through the sight glass (shown in Fig 3), according to the following indicators:

Fig 3: Refrigerant Volume Inspection
G93I56448Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PROPERLY CHARGED SYSTEM

  • Almost no air bubbles are seen in the flow of refrigerant. See Fig 3. When raising the engine speed gradually from idle to 1500 rpm, the bubbles disappear, making the refrigerant transparent.

INSUFFICIENTLY CHARGED SYSTEM

  • air bubbles seen continuously in the refrigerant. See Fig 3.

EXCESSIVELY CHARGED SYSTEM

  • No air bubbles seen in the refrigerant flow
REFRIGERANT VOLUME INSPECTION

Item Symptom Amount of Refrigerant Remedy
1 Bubbles present in sight glass (see note below) Insufficient Check for gas leakage w/gas leak tester & repair if necessary. Add refrigerant until bubbles disappear.
2 No bubbles present in sight glass None, sufficient or too much Refer to items 3 and 4.
3 No temperature difference between compressor inlet and outlet Empty or nearly empty Check for gas leakage w/gas leak tester & repair if necessary. Add refrigerant until bubbles disappear.
4 Temperatures of compressor inlet and outlet are noticeably different Correct or too much Refer to items 5 and 6.
5 Immediately after air conditioner is turned off, refrigerant in sightglass stays clear Too much Recover refrigerant Evacuate air & charge proper amount of purified refrigerant
6 When air conditioner is turned off, refrigerant foams briefly and then stays clear Correct ---
With higher ambient temperatures (above about 85°F), bubbles in the sight glass can be considered normal if cooling is suffecient.

LEAK DETECTION

Identifying the exact location of A/C refrigerant leaks must be done with great care and can sometimes be difficult.

  1. Ensure that at least 1 lb. (450 g) of refrigerant is in the system.
  2. Install a gauge set and operate the A/C system to obtain normal system pressures. (Low: 21-28 psi, Hi: 206-213 psi)
  3. Stop engine and allow low side pressure to peak.
  4. Always use a proper gas leak detector for the refrigerant you are working with.
    1. Do not use propane type testers.
    2. Always allow full warm-up of electronic type testers.
    3. Calibrate instrument according to manufacturer's instructions.
    4. Do not get probe wet or oily, etc.
  5. Inspect the A/C system according to the following A/C system inspection procedures.
NOTE: Before performing any repairs, connect and use the Refrigerant Recovery Machine.
Fig 4: A/C SYSTEM INSPECTION PROCEDURE PART 1
GB0043211Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 5: A/C SYSTEM INSPECTION PROCEDURE PART 2
GB0043212Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

GAS LEAK INSPECTION

CONNECTION INSPECTION AND REPAIR PROCEDURE

  1. Check for gas leaks.
  2. Check connection torque. If connections are torqued properly, go to Step 5.
  3. Tighten and torque connector.
  4. Re-check for gas leaks.
  5. Inspect O-ring and connection. See Fig 6. Refer to reference publications to obtain correct torque value and determine O-ring lubrication requirements.
  6. Install new O-ring and replace any damaged components.
  7. Re-check for gas leaks.
    NOTE: Carefully check each connection in the refrigerant system:
    • Pipe to pipe
    • Pipe to each functional A/C component
Fig 6: O-Ring Inspection
G93J56449Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OUTLET OF COOLING UNIT DRAIN HOSE

FOR MODEL APPLICATIONS WHICH ALLOW CHECKING FOR GAS LEAKS INSIDE COOLING UNIT

  • Celica
  • Camry
  • Corolla
  • Paseo
  • Land Cruiser
  • Previa
  • Tercel
  1. Check for gas leak at drain hose. Check with gas leak detector at outlet of cooling unit drain hose. Use the following procedures to check inside cooling unit.
    1. Disconnect negative (-) battery terminal.
    2. Remove parts surrounding cooling unit.
    3. Remove evaporator cover.
    4. Clear any residual gas in the cooling housing by blowing with low pressure compressed air.
    5. If possible, insert a partition of plastic or cardboard between expansion valve/liquid tube and evaporator to more easily pinpoint gas leak location. See Fig 7.
      Fig 7: Expansion Valve/Liquid Tube Location
      G93D56450Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    6. Check for gas leak at the following locations:
      • Mating surfaces of expansion valve and evaporator or expansion valve and liquid tube
      • Expansion valve adjustment screw
      • Evaporator Tubes
  2. Check for gas leak on liquid tube and expansion valve. If no leak is present, go to Step 5.
  3. Replace liquid tube and expansion valve.
  4. Re-check gas leak.
  5. Check gas leak at evaporator.
  6. Replace evaporator.
  7. Re-check for gas leak.

FOR MODELS ON WHICH IT IS NOT POSSIBLE TO CHECK FOR GAS LEAKS INSIDE THE COOLING UNIT

  • Truck
  • 4-Runner
  • Supra
  • MR2
  • Cressida
  1. Check for gas leak. Check with gas leak detector at outlet of cooling unit drain hose.
  2. Replace liquid tube and expansion valve and O-rings.
  3. Re-check for gas leak.
  4. Replace evaporator.
  5. Re-check for gas leak.

CONDENSER/RECEIVER DRIER/COMPRESSOR

  1. Check for gas leak. Check affected components by using the gas leak detector:
    • All portions of condenser
    • Compressor shaft seal and body seals
    • Compressor lock sensor
  2. Replace affected parts.
  3. Re-check for gas leak.

AIR CONDITIONING SYSTEM COOLING UNIT COMPONENT LOCATION

A/C system for single and dual evaporator model vehicles are shown in Fig 8 and Fig 9 respectively.

Fig 8: A/C System for Single Evaporator (all Passenger Cars)
G93E56451Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 9: A/C System for Dual Evaporator (Previa)
G93F56452Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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