Heating, Ventilation, and Air Conditioning: Other GMC Sierra III

Handling of Refrigerant Lines and Fittings

1. Keep all metal tubing lines free of dents or kinks. Any line restrictions will cause the loss of system capacity.
2. Never bend a flexible hose line to a radius of less than four times the diameter of the hose.
3. Never allow a flexible hose line to come within 65 mm (2-1/2 in) of the exhaust manifold.
4. Inspect flexible hose lines regularly for leaks or brittleness.
5. Replace flexible hose lines with new lines if you find signs of deterioration or leaking.
6. Discharge the refrigeration system of all refrigerant before disconnecting any fitting in the refrigeration system.
7. Proceed very cautiously regardless of the gauge readings.
8. Open the fittings very slowly.
9. If you notice pressure when you loosen a fitting, allow the pressure to bleed off as described Discharging, Adding Oil, Evacuating and Charging Procedures for A/C System.
10. Cap or tape any refrigerant line immediately after it is opened. This will prevent the entrance of moisture and dirt, which can cause internal compressor wear or plugged lines in the condenser, the evaporator core, the expansion valve or the compressor inlet screens. NOTE: Use two proper wrenches to connect the fittings.
11. Back up the opposing fitting to prevent distortion of the connecting lines or the components.
12. Keep the sealing surfaces in perfect condition. A burr or a piece of dirt may cause a refrigerant leak.
13. When seal washers are used, always install the seal washer without lubrication.
14. When O-rings are used, always lightly coat the new O-ring seal with mineral base 525 viscosity refrigerant oil prior to installation.

Fluorescent Leak Detector

Note. Always use UV protective eyewear when working with UV light.

Fluorescent dye will assist in locating any leaks in the A/C system.

1. Condensation on the evaporator core or the refrigerant lines may wash the PAG oil and fluorescent dye away from the actual leak. Condensation may also carry dye through the HVAC module drain.
2. Leaks in the A/C system will be indicated in a light green or yellow color when using the leak detection lamp. Use the leak detection lamp in the following areas: All fittings or connections that use seal washers or O-rings All of the A/C components The A/C compressor shaft seal The A/C hoses and pressure switches The HVAC module drain tube, if the evaporator core is suspected of leaking The service port sealing caps The sealing cap is the primary seal for the service ports.
3. Follow the instructions supplied with the GE-42220 lamp.
4. To prevent false diagnosis in the future, thoroughly clean the residual dye from any area where leaks were found. Use a rag and the approved GE-43872 cleaner.

Fluorescent Dye Injection

1. Not all of the fluorescent dyes are compatible with GM refrigerant systems. Using dyes not approved by GM may damage the vehicle's refrigerant system.
2. To prevent false diagnosis, thoroughly clean any residual dye from the service port with a rag and the approved fluorescent dye cleaner GE-43872 dye cleaner.

Electronic Leak Detection

Infrared detectors operate differently than heated sensor type detectors. They detect changes in concentration of refrigerant rather than absolute concentration. If the tip is held at a detected leak for more than 5 seconds the detector will saturate and zero to that concentration and will no longer detect leaks at that concentration or less. Move tip away from the leak saturation area for 30 seconds to reset the sensitivity of the detector.

Adequate system pressure is required for effective leak detection.

1. If system is empty install 10% of system charge.
2. Temperature must be above 60 F.

Do not use

1. Soap solutions (not effective for leak detection)
2. Shop air (will introduce contamination to the refrigerant system)
3. High pressure gasses i.e. nitrogen (may cause system damage

Air movement from the engine cooling fan can affect the detectors ability to detect leaks. Always leak test with engine off and if possible after engine has reached normal operating temperature.

1. All fittings and components should be checked.
2. Take care not to contaminate the probe tip if the part being tested is contaminated.
3. No cleaners containing solvents should be used prior to using electronic leak detector.
4. Always follow the refrigerant system around in a continuous path so that no areas of potential leaks are missed. Move the tip along the refrigerant system at a rate of no more than 3 inches per second and a distance of 3/8 inch from the surface being tested. If a leak is found, always continue to test the remainder of the system.

Follow the instructions supplied with the GE-50078 detector.

Defrosting Insufficient

Defrosting Insufficient

Eliminating Air Conditioning Odor

Odors may be emitted from the air conditioning system primarily at start up in hot, humid climates. The following conditions may cause the odor

1. Debris is present in the HVAC module.
2. Microbial growth on the evaporator core

When the blower motor fan is turned on, the microbial growth may release an unpleasant musty odor into the passenger compartment. To remove odors of this type, the microbial growth must be eliminated. Perform the following procedure

Deodorize the evaporator core using Deodorizing Aerosol Kit.

Perform the following steps in order to deodorize the A/C system

1. Ensure that the plenum which draws outside air into the HVAC module is clear of debris.
2. Disable the A/C compressor clutch operation by disconnecting the clutch coil electrical connector.
3. Dry the evaporator core by performing the following steps: Start the engine. Select the warmest temperature setting. Select the recirculation mode. Run the blower motor on high for 10 minutes.
4. Locate an area in the air conditioning duct between the blower motor and the evaporator core downstream of the blower motor.
5. Drill a 3.175 mm (0.125 in) hole where the hole will not interfere with or damage the following components: The blower motor The evaporator core Any other operating part the of system
6. Wear safety goggles and latex gloves in order to perform the following actions: Select the maximum blower speed. Insert the deodorizer extension tube into the hole to the mark on the extension tube. Use short spray bursts and vary the direction of spray for a 2-3 minute period of time.
7. Shut the engine OFF. Allow the vehicle to sit for 3-5 minutes.
8. Seal the 3.175 mm (0.125 in) hole with body sealer or RTV gasket compound.
9. Start the engine.
10. Operate the blower motor on high for 15-20 minutes to dry.
11. Reconnect the A/C compressor clutch coil electrical connector.
12. Verify proper clutch operation.

A/C Refrigerant System Oil Charge Replenishing

If oil was removed from the A/C system during the recovery process or due to component replacement, the same quantity of PAG oil must be replenished. If no oil was removed from the A/C system during recovery, do not charge any PAG oil into the A/C system. Oil can be injected into a charged system using J-45037 A/C Oil Injector. For the proper quantities of oil to add to the A/C refrigerant system, refer to Refrigerant System Specifications .

Tools Required

1. J 41447 R-134A A/C Tracer Dye - Box of 24
2. J 42220 Universal 12V Leak Detection Lamp
3. J 43600 ACR 2000 Air Conditioning Service Center
4. J 45268 A/C Flushing Adapter Kit

Note. Flushing with the J 43600 ACR 2000 Air Conditioning Service Center is not intended to remove metal from the A/C system.

Flushing is intended to remove the following

1. Contaminated PAG oil
2. Desiccant, following a desiccant bag failure
3. Overcharge of PAG oil
4. Refrigerant contamination

Engine Coolant

Engine coolant is the key element of the heating system. The engine thermostat controls the normal engine operating coolant temperature. Coolant pumped out of the engine enters the heater core through the inlet heater hose. The air flowing through the HVAC module absorbs the heat of the coolant flowing through the heater core. The coolant then exits the heater core through the heater outlet hose and returns back to the engine block.

A/C Cycle

Refrigerant is the key element in an air conditioning system. R-134a is presently the only approved refrigerant for this vehicle. R-134a is a very low temperature gas that can transfer the undesirable heat from the passenger compartment to the outside air.

The A/C compressor is belt driven and operates when the magnetic clutch is engaged. The compressor builds pressure in the A/C system. Compressing the refrigerant also adds heat to the refrigerant. The refrigerant is discharged from the compressor through the discharge hose and forced to flow to the condenser and then through the balance of the A/C system. The A/C system is mechanically protected with the use of a high pressure relief valve. If the high pressure A/C switch were to fail or if the refrigerant system becomes restricted and refrigerant pressure continued to rise, the high pressure relief will pop open and release refrigerant from the system.

Compressed refrigerant enters the condenser in a high temperature, high pressure vapor state. As the refrigerant flows through the condenser, the heat of the refrigerant is transferred to the ambient air passing through the condenser. Cooling the refrigerant causes the refrigerant to condense and change from a vapor to a liquid state.

The condenser is located in front of the radiator for maximum heat transfer. The condenser is made of aluminum tubing and aluminum cooling fins, which allows rapid heat transfer for the refrigerant. The semi-cooled liquid refrigerant exits the condenser and flows through the liquid line, to the TXV.

The TXV is located at the evaporator inlet. The TXV is the dividing point for the high and the low pressure sides of the A/C system. As the refrigerant passes through the TXV, the refrigerant is lowered. Due to the pressure differential on the liquid refrigerant, the refrigerant will begin to boil at the TXV. The TXV also meters the amount of liquid refrigerant that can flow into the evaporator.

Refrigerant exiting the TXV flows into the evaporator core in a low pressure, liquid state. Ambient air is drawn through the HVAC module and passes through the evaporator core. Warm and moist air will cause the liquid refrigerant to boil inside the evaporator core.

The boiling refrigerant absorbs heat from the ambient air and draws moisture onto the evaporator. The refrigerant exits the evaporator through the suction line and back to the compressor, in a vapor state. This completes the A/C cycle of heat removal. At the compressor, the refrigerant is compressed again and the cycle of heat removal is repeated.

The conditioned air is distributed through the HVAC module for passenger comfort. The moisture removed from the passenger compartment will also change form or condense and is discharged from the HVAC module as water.