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

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.

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.

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

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.

Refrigerant Recovery and Recharging (HP2)

Special Tools

1. J 43600: ACR 2000 Air Conditioning Service Center
2. J 45037: A/C Oil Injector
3. GE 48997: Hybrid A/C Oil Injector Adapter Hose

For equivalent regional tools, refer to Special Tools .

The J 43600: service center is a complete air conditioning service center for R-134a. The ACR 2000 recovers, recycles, evacuates and recharges A/C refrigerant quickly, accurately and automatically. The unit has a display screen that contains the function controls and displays prompts that will lead the technician through the recover, recycle, evacuate and recharge operations. R-134a is recovered into and charged out of an internal storage vessel. The ACR 2000 automatically replenishes this vessel from an external source tank in order to maintain a constant 5.45-6.82 kg (12-15 lbs) of A/C refrigerant.

The ACR 2000 has a built in A/C refrigerant identifier that will test for contamination, prior to recovery and will notify the technician if there are foreign gases present in the A/C system. If foreign gases are present, the ACR 2000 will not recover the refrigerant from the A/C system.

The ACR 2000 also features automatic air purge, single pass recycling and an automatic oil drain.

Refer to the J 43600: service center manual for operation and setup instruction. Always recharge the A/C System with the proper amount of R-134a. Refer to Refrigerant System Specifications (HP2) for the correct amount.

A/C Refrigerant System Oil Charge Replenishing

If POE oil was removed from the A/C system during the recovery process or due to component replacement, the oil must be replenished. POE Oil can be injected into a charged system using J 45037: injector along with GE 48997: adapter hose. For the proper quantities of oil to add to the A/C refrigerant system, refer to Refrigerant System Specifications (HP2) .

Refrigerant Recovery and Recharging (Non-HP2)

Special Tools

1. J 43600: ACR 2000 Air Conditioning Service Center
2. J 45037: A/C Oil Injector

For equivalent regional tools, refer to Special Tools .

The J 43600: service center is a complete air conditioning service center for R-134a. The ACR 2000 recovers, recycles, evacuates and recharges A/C refrigerant quickly, accurately and automatically. The unit has a display screen that contains the function controls and displays prompts that will lead the technician through the recover, recycle, evacuate and recharge operations. R-134a is recovered into and charged out of an internal storage vessel. The ACR 2000 automatically replenishes this vessel from an external source tank in order to maintain a constant 5.45-6.82 kg (12-15 lbs) of A/C refrigerant.

The ACR 2000 has a built in A/C refrigerant identifier that will test for contamination, prior to recovery and will notify the technician if there are foreign gases present in the A/C system. If foreign gases are present, the ACR 2000 will not recover the refrigerant from the A/C system.

The ACR 2000 also features automatic air purge, single pass recycling and an automatic oil drain.

Refer to the J 43600: service center ACR 2000 manual for operation and setup instruction. Always recharge the A/C System with the proper amount of R-134a. Refer to Refrigerant System Specifications (Non-HP2) for the correct amount.

If oil was removed from the A/C system during the recovery process or due to component replacement, the oil must be replenished. Oil can be injected into a charged system using J 45037: injector. For the proper quantities of oil to add to the A/C refrigerant system, refer to Refrigerant System Specifications (Non-HP2) .

Balancing Procedure

1. Before installing the compressor, the refrigerant oil will have to be fully drained.
2. Add back the same quantity of polyalkylene glycol (PAG) oil as drained from the removed compressor. Refer to the amount of refrigerant oil recorded during the compressor removal.

Air Conditioning Compressor Oil Balancing (HP2)

Special Tools

1. GE-48997 A/C POE Oil Injector (HP2). See «Special Tools»(ref-364481-S11510526782010063000000) .
2. J 39400-A Halogen Leak Detector. See «Special Tools»(ref-364481-S11510526782010063000000) .
3. J 45037 A/C Oil Injector. See «Special Tools»(ref-364481-S11510526782010063000000) .

Tools Required

J 41425 A/C Line Repair Kit. See Special Tools .

The rear A/C or heater lines can be repaired in sections.

Replacement lines through GMSPO contains all 4 lines in two sections.

Use the J 41425 when any of the following actions damage the rear A/C or heater lines: See Special Tools .

1. Rub-through
2. Collision damage
3. Leakage in the system

Minimum Tube Length Required Table

Follow the Straight Line Repair procedure in order to repair line damage in a straight section of line.

Follow the Line Sectioning Repair procedure in order to repair any damage in a bend area. Do not repair the rear A/C or heater lines in a bend area, replace the lines. Maintaining the original line shape will prevent vibrations and rub-through.

Straight Line Repair

1. Recover the refrigerant, if repairing the A/C lines. Refer to «Refrigerant Recovery and Recharging (HP2)»(ref-364481-S08730334532010063000000) or «Refrigerant Recovery and Recharging (Non-HP2)»(ref-364481-S37774139622010063000000) .
2. Drain the coolant, if repairing the heater lines. Refer to «Cooling System Draining and Filling (Static Fill)»(ref-364492-S20837984752010063000000) .
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-364496-S07186948972010063000000) .
4. Locate the area that requires repair.
5. Obtain a length of replacement line to make the repair.
6. Use a tubing cutter in order to cut and remove the section of damaged line.
7. Use a tubing cutter in order to cut the replacement line to length.
8. Use the cleaning pad from the J 41425 in order to clean any burrs or grease from the line ends. See «Special Tools»(ref-364481-S11510526782010063000000) . Be sure to clean at least 19 mm (0.75 in) from the line ends.
9. Use the LOK prep sealant in order to prep the line ends.
10. Apply one drop of the J 41425-3 sealing compound to the outside of each end of the line.
11. Insert the line ends into the LOK fitting.
12. Rotate the LOK fitting one complete turn in order to evenly distribute the sealing compound around the lines.
13. Install the correct LOK fitting jaws into the J 41425-1 tool.
14. Install the J 41425-1 tool over the LOK connectors. Verify that the LOK connector ends are positioned in the counter bores of the jaws.
15. Tighten the forcing screw of the J 41425-1 tool. When fully seated, the LOK connector collars will bottom out on the center shoulder of the LOK fitting.
16. Loosen the forcing screw and remove the J 41425-1 tool from the repaired line.
17. Repeat Step 8 through Step 16 to repair the other end of the line.
18. Verify that the LOK fittings are correctly installed.
19. Lower the vehicle.
20. Refill the coolant, if drained. Refer to «Cooling System Draining and Filling (Static Fill)»(ref-364492-S20837984752010063000000) .
21. Evacuate and recharge the refrigerant, if repairing the A/C lines. Refer to «Refrigerant Recovery and Recharging (HP2)»(ref-364481-S08730334532010063000000) or «Refrigerant Recovery and Recharging (Non-HP2)»(ref-364481-S37774139622010063000000) .

Line Sectioning Repair

1. Recover the refrigerant, if repairing the A/C lines. Refer to «Refrigerant Recovery and Recharging (HP2)»(ref-364481-S08730334532010063000000) or «Refrigerant Recovery and Recharging (Non-HP2)»(ref-364481-S37774139622010063000000) .
2. Drain the coolant, if repairing the heater lines. Refer to «Cooling System Draining and Filling (Static Fill)»(ref-364492-S20837984752010063000000) .
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-364496-S07186948972010063000000) .
4. Obtain a new A/C or heater line for sectioning.
5. Scribe a mark on the line that will be sectioned.
6. Use a tubing cutter in order to cut the line or lines being replaced.
7. Remove the section of line being replaced from the vehicle.
8. Install the replacement line to the vehicle.
9. Use a tubing cutter in order to cut the replacement line to length.
10. Use the cleaning pad from the J 41425 in order to clean any burrs or grease. See «Special Tools»(ref-364481-S11510526782010063000000) . Be sure to clean at least 19 mm (0.75 in) from the A/C line.
11. Use the LOK prep sealant in order to prep the A/C or heater line.
12. Apply one drop of the J 41425-3 sealing compound to the outside of each line end.
13. Insert the line ends into the LOK fitting.
14. Rotate the LOK fitting one complete turn in order to evenly distribute the sealing compound around the lines.
15. Install the correct LOK fitting jaws into the J 41425-1 tool.
16. Install the J 41425-1 tool over the LOK connectors. Verify that the LOK connector ends are positioned in the counter bores of the jaws.
17. Hold the tool body with a 3/8" breaker bar. Turn the forcing screw until both of the connector collars bottom on the center shoulder of the LOK fitting.
18. Loosen the forcing screw. Remove the tool from the repaired line.
19. Verify that the LOK fitting is correctly installed.
20. Lower the vehicle.
21. Refill the coolant, if drained. Refer to «Cooling System Draining and Filling (Static Fill)»(ref-364492-S20837984752010063000000) .
22. Evacuate and recharge the refrigerant, if repairing the A/C lines. Refer to «Refrigerant Recovery and Recharging (HP2)»(ref-364481-S08730334532010063000000) or «Refrigerant Recovery and Recharging (Non-HP2)»(ref-364481-S37774139622010063000000) .

Engine Coolant

Engine coolant is the essential element of the heating system. The thermostat controls the normal engine operating coolant temperature. The thermostat also creates a restriction for the cooling system that promotes a positive coolant flow and helps prevent cavitation.

Coolant enters the heater core through the inlet heater hose, in a pressurized state. The heater core is located inside the HVAC module. The ambient air drawn through the HVAC module absorbs the heat of the coolant flowing through the heater core. Heated air is distributed to the passenger compartment, through the HVAC module, for passenger comfort. Opening or closing the air temperature door controls the amount of heat delivered to the passenger compartment. The coolant exits the heater core through the return heater hose and recirculated back through the engine cooling system.

A/C Cycle

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

The electric A/C compressor is a self contained high voltage inverter, electric motor, and direct coupled compressor. The electric A/C compressor requires the high voltage system on the vehicle to be engaged and operates on command from the climate control panel. The electric A/C compressor has the ability to run and provide cooling performance while the vehicle engine is not running. This feature enables the electric A/C compressor to run at a speed independent of the engine. The control system will command the electric A/C compressor to a speed necessary to maintain a desired cooling level rather than cycle the electric A/C compressor on and off. Limits of operation for the electric A/C compressor are controlled by software within the climate control panel. The electric A/C compressor builds pressure on the vapor refrigerant. 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 A/C refrigerant pressure sensor 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 orifice tube.

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

Refrigerant exiting the orifice tube 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, and completing 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 heat and moisture removed from the passenger compartment will also change form, or condense, and is discharged from the HVAC module as water.

A/C Cycle with Auxiliary

The auxiliary A/C system operates from the vehicles primary A/C system. The front or primary A/C system must be ON to allow the rear A/C system to function.

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

The A/C system used on this vehicle is a non cycling system. Non cycling A/C systems use a high pressure switch to protect the A/C system from excessive pressure. The high pressure switch will OPEN the electrical signal, to the compressor clutch, in the event that the refrigerant pressure becomes excessive. After the high and low side of the A/C system pressure equalize, the high pressure switch will CLOSE. Closing the high pressure switch will complete the electrical circuit to the compressor clutch. The A/C system is also mechanically protected with the use of a high pressure relief valve. If the high pressure 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.

The electric A/C compressor is a self contained high voltage inverter, electric motor, and direct coupled compressor. The electric A/C compressor requires the high voltage system on the vehicle to be engaged and operates on command from the climate control panel. The electric A/C compressor has the ability to run and provide cooling performance while the vehicle engine is not running. This feature enables the electric A/C compressor to run at a speed independent of the engine. The control system will command the electric A/C compressor to a speed necessary to maintain a desired cooling level rather than cycle the electric A/C compressor on and off. Limits of operation for the electric A/C compressor are controlled by software within the climate control panel. The electric A/C compressor builds pressure on the vapor refrigerant. 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.

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. The liquid line flow is split and the liquid refrigerant flows to both the front or primary A/C system, and to the liquid line for the rear A/C system.

The liquid refrigerant, flowing to the rear A/C system, flows into the rear thermal expansion valve (TXV). The rear TXV is located at the rear evaporator inlet. The TXV is the dividing point for the high and the low pressure sides of the rear A/C system. As the refrigerant passes through the TXV, the pressure on the refrigerant is lowered. Due to the pressure differential on the liquid refrigerant, the refrigerant will begin to boil at the expansion device. 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 rear A/C module and passes through the evaporator core. Warm and moist air will cause the liquid refrigerant boil inside of 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 primary A/C systems suction line. Refrigerant in the primary A/C system suction line flows back to the compressor, in a vapor state, and 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 rear A/C module for passenger comfort. The heat and moisture removed from the rear passenger compartment will also change form, or condense, and is discharged from the rear A/C module as water.