Tools Required
| • | J 39500-50
23 Kg (50 lb) Refillable Recovery Tank |
Caution: Do not operate the detector in a combustible atmosphere since its sensor
operates at high temperature. Personal injury or damage to the equipment may
result.
Important: Vehicles equipped with an early warning system for low refrigerant may
set low refrigerant diagnostic trouble codes (DTCs) in the PCM.
Perform a refrigerant leak test on the system whenever a leak is suspected.
Suspect leakage when a system indication of a low charge occurs or after
any service operation which disturbs the following parts:
Halogen Leak Detector
The Halogen Leak Detector is the most useful tool in locating refrigerant
leaks. TheJ 39400
is
a small unit which operates on 12 V DC and provides an audible signal
which increases in frequency as R-12 or R-134a is detected. There are three
settings:
Use the gross leak setting for isolating very large leaks already found
in one of the other two settings.
Ensure that the instrument is properly calibrated according the instrument's
instructions. Ensure that the detector is set properly for the type of refrigerant
system being tested.
Prior to beginning the test, ensure that the refrigerant system is sufficiently
charged for leak testing by measuring the static pressure with a gauge set.
Readings in the range 413-689 kpa (60-100 psi)
are acceptable to conduct a leak test.
The most common leaks are found at the refrigerant fittings or connections.
Leaks may be caused by the following items:
| • | Lack of lubricant on the O-rings |
| • | Dirt/debris across the O-ring |
A small piece of lint from cotton gloves or shop cloths can create a
leak path across an O-ring.
The successful use of this and any other electronic leak detector depends
on the scan rate. Successful use also depends on carefully following the manufacturer's
instructions regarding the following items:
Each joint must be completely circled moving at 1-2 inches
per second with the tip of the probe as close to the surface as possible.
The tip must be no more than 1/4 inch away and without blocking air
intake. A leak is indicated when the audible tone goes from a steady 1-2 clicks
per second to a solid alarm. Adjust the balance knob frequently in order
to maintain the 1-2 clicks per second rate.
Important: Halogen leak detectors are sensitive to the following items:
| • | Windshield washing solutions |
| • | Low and high side sensors |
| • | Transducers and switches |
| • | Evaporator inlet and outlet |
| • | Accumulator dryer inlet and outlet |
| • | Condenser inlet and outlet |
| • | All brazed and welded areas |
| • | Areas showing signs of damage |
Important: Always follow the refrigerant system around in a continuous path so
that no areas of potential leaks are missed. Test all of the above areas in
order to ensure that the entire system is leak free, even when a leak was
already found.
Fluorescent Leak Detector
Tools Required
| • | J 41459 R134a
Leak Detection Dye Injector |
R-134a refrigerant is uniquely different from R-12 refrigerant used
in the past and may require additional methods in order to detect leaks. The
R-134a molecule is smaller than the R-12 molecule and can leak through
smaller openings. R-134a does not contain chlorine which the electronic leak
detectors found easy to identify. The leak detection dye method is meant
to be used in conjunction with the electronic leak detector. The leak detection
dye method will pinpoint smaller leaks undetected by the electronic leak
detector. Leak detection dye requires time. Depending upon the rate of the
leak, the leak may take up to 7 days to become visible.
Important:
| • | The J 41447
has been developed to be used only with R-134a equipped vehicles or vehicles
that have been retrofitted from R-12 to R-134a. |
| • | Only J 41447
is recommended for use in the R134a system. Use of any other products may
affect system reliability and cause premature compressor failure. |
| • | Use only a 0.069-N (¼-ounce) charge of tracer dye. Larger
amounts may compromise the reliability of the A/C system. |
| • | After adding leak detection dye, clean service valves and surfaces
of residual dye with GM Engine Degreaser GM P/N 1050436 or the equivalent,
in order to prevent false diagnosis. |
Dye Injection
| • | Charged systems can be injected with tracer dye by using the J 41459
along with the instructions
provided. |
| • | Discharged systems can have the leak detection dye added to a
replaced component, or can be added using the J 41459
. |
Liquid Leak Detectors and Pressure Testing
Liquid/bubbles leak detectors have very limited usefulness. This is
due to the restricted visibility in today's refrigerant systems and liquid/bubbles leak
detectors' lack of sensitivity.
Evaporator Core
One of the most difficult leaks to find is in the evaporator core. Follow
the instructions below in order to lead test the core:
- Turn the blower fan on high for 15 or more seconds.
- Shut off the blower fan.
- Wait 10 minutes.
- Remove the blower fan power module or resistor block, if accessible.
- If the blower fan power module is not accessible, inspect the
condenser drain tube for moisture.
- If the condenser drain tube is dry, use the condenser drain tube
instead.
- Insert the leak detector probe into the resistor/relay opening,
or the blower case drain tube. If the detector goes to a solid alarm, a leak
has been found.
- Inspect the core face for evidence of refrigerant oil with a flashlight.
On R-134a systems, the lubricant is water soluble so no evidence of oil is
likely, even with a leak.
Compressor Shaft Seal
- Blow shop air behind and in front of the compressor clutch/pulley
for at least 15 seconds.
- Wait 1-2 minutes.
- Probe the area in front of the pulley. If the detector goes to
a solid alarm, a leak has been found.
