Refrigerant: Testing and Inspection

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

CAUTION: Take care to prevent personal injury which could occur due to touching a hot engine when testing. Tests should be done with the engine "OFF" and as cool as possible. Do not operate the detector in a combustible atmosphere since its sensor operates at high temperature.

Perform a refrigerant leak test under the following conditions:
- Whenever you suspect a leak
- After a service operation that disturbs the components, lines or connections

There are several methods and special tools available for leak testing. Use care in all cases.




Electronic Leak Detector




Tools Required

J 39400-A Electronic Leak Detector

IMPORTANT: Electronic leak detectors are sensitive to the following liquids:
- Windshield washing solutions
- Solvents
- Cleaners
- Adhesives

Ensure that the surfaces are clean in order to prevent a false warning. Ensure that the surfaces are dry as ingestion of liquids will damage the detector.

The J 39400-A is useful for locating refrigerant leaks. The J 39400-A operates on a 12 volt DC and emits signal that increases in frequency as R-134a is detected. Calibrate the instrument according to the included instructions. Ensure that the detector is properly calibrated for the type of refrigerant that you are testing. Place the GAS switch in the R-134a setting prior to testing.

Most leaks are found at the refrigerant fittings and connections. These leaks can be caused by the following conditions:
- Improper torque
- Damaged O-rings
- Lack of lubricant on the O-ring seals
- Dirt or debris on the O-ring seals.
- Lint from cotton gloves or shop cloths

IMPORTANT: Follow the refrigerant system around a continuous path so that no potential leaks are missed. Test all areas of the system in order to ensure the entire system is leak free, even if you have already found a leak.

Observe the scan rate and follow the manufacturer's instructions when using the electronic leak detector. Encircle each joint with the tip of the probe moving at 25 - 51 mm (1 - 2 in) per second. Ensure that the tip of the probe is no more than 6 mm (0.25 in) away from the surface without blocking the air intake. An audible tone that goes from 1 - 2 clicks per second to a solid alarm indicates a leak. Adjust the balance arm frequently in order to maintain the clicks.

Use this procedure in order to test the following components:
- The evaporator inlet and outlet
- The accumulator inlet and outlet
- All of the brazed and welded areas
- Areas that show signs of damage
- Hose couplings
- The compressor rear head
- Housing joints

Service Ports/Access Valves
The sealing cap is the primary seal for the service ports. The cap contains a specially designed O-ring or gasket that provides a leak-free seal. The following conditions will result in a loss of refrigerant charge:
- A missing cap
- A wrong cap

Evaporator Core
Leaks in the evaporator core are the most difficult to find. Use the following procedure in order to test the core:

1. Turn on the blower fan to HI for 15 seconds or longer.
2. Turn off the blower fan.
3. Wait 10 minutes.
4. Remove the blower motor resistor. Refer to Blower Motor Resistor Replacement.
5. Insert the leak detector probe as close to the evaporator as possible. If the detector emits a solid alarm, a leak has been found.
6. Use a flashlight in order to visually inspect the core face for evidence of refrigerant oil.

Compressor Block Fitting and Shaft Seal
1. Blow shop air behind the compressor/clutch pulley and in front of the compressor/clutch pulley for at least 15 seconds.
2. Wait 1 - 2 minutes.
3. Use the detector in order to probe the area in front of the pulley.
If the detector emits a solid alarm, a leak has been found




NOTE: The use of proper wrenches when loosening or making connections is important. A backup wrench should be used on the brazed or welded fitting to prevent distortion of A/C lines.

Important
- Before opening the refrigeration system, make sure the work area is well ventilated. Welding or steam-cleaning operations should not be done on or near refrigeration system lines or other air conditioning parts on the vehicle.
- All metal tubing lines should be free of dents or kinks to prevent loss of system capacity due to line restriction.
- The flexible hose lines should never be bent to a radius of less than four times the diameter of the hose.
- The flexible hose lines should never be allowed to come within a distance of 6.5 mm (2.5 inches) of the exhaust manifold.
- Flexible hose lines should be inspected regularly for leaks or brittleness. Replace with new lines if deterioration or leaking is found.
- When disconnecting any fitting in the refrigerant system, recover all Refrigerant-134a. However, proceed very cautiously, regardless of the gauge readings. Open very slowly, keeping your face and hands away so that no injury can occur. If pressure is noticed when a fitting is loosened, allow it to bleed off very slowly.

NOTE: Never use alcohol in the refrigeration system to remove moisture. Damage to the system components may occur.

- If any refrigerant line is opened to the atmosphere, cap it immediately to prevent the entrance of moisture and dirt. These can cause internal compressor wear or plugged lines in the condenser and evaporator core and expansion (orifice) tubes or compressor inlet screens.
- Remove sealing caps from subassemblies just before making connections for final assembly. Use a small amount of clean 525 viscosity refrigerant oil on all tube and hose joints. Use new O-ring seals dipped in 525 viscosity refrigerant oil when assembling joints. The oil will aid in assembly and help to provide a leakproof joint. O-ring seals and seats must be in perfect condition. A burr or a piece of dirt can cause a refrigerant leak.

Using The Two Wrench Method:

Proper O-ring Installation:

Improper O-ring Installation:

Refrigerant Line Installation:

- Use the proper wrenches when making connections on O-ring seal fittings. Using improper wrenches may damage the connection. The opposing fitting should always be backed up with a wrench to prevent distortion of connecting lines or components. When connecting the flexible hose connections, it is important that the swaged fitting and the flare nut, as well as the coupling to which it is attached, be held at the same time using three different wrenches to prevent turning the fitting and damaging the seat.

Tighten tubing connections to the specified torque. Refer to Fastener Tightening Specifications.