Leak Testing
Special Tools
- J 39400-A Halogen Leak Detector
- J 41447 R-134A A/C Tracer Dye-Box of 24
- J 42220 Universal 12V Leak Detection Lamp
- J 43872 Fluorescent Dye Cleaner
- J 46297 A/C Dye Injector Kit
- J 46297-12 Replacement Dye Cartridges
Refrigerant Leak Testing
Note. General Motors vehicles are now manufactured with fluorescent dye installed directly into the air conditioning (A/C) system.
The fluorescent dye mixes and flows with the polyalkylene glycol (PAG) oil throughout the refrigerant system.
Verifying some passive leaks may require using the J 39400-A halogen leak detector, even though the A/C system contains fluorescent dye.
The only time that adding additional fluorescent dye is required is after flushing the A/C system.
Air Conditioning (A/C) System Performance Test
This test measures the operating efficiency of the A/C system under the following conditions
- The current ambient air temperature
- The current relative humidity
- The high side pressure of the A/C system
- The low side pressure of the A/C system
- The temperature of the air being discharged into the passenger compartment
A/C Diagnostics Chart
| Low Side Gauge Reading | High Side Gauge Reading | Potential Causes |
|---|---|---|
| Low | Low | Low Refrigerant Charge |
| Restriction between Compressor and High Side port | ||
| Low/Normal | Evaporator Freezing | |
| High | Restriction between the Low Side and High Side ports or Restricted TXV/Orifice Tube | |
| Compressor Stuck at Maximum Displacement | ||
| High | Low | Compressor has Low Displacement or Internal Malfunction |
| High | Malfunctioning Cooling Fans | |
| Refrigerant Overcharge | ||
| Restriction between the Low Side Port and Compressor Inlet | ||
| Restricted Condenser Air Flow | ||
| Expansion Device Stuck Open | ||
| Air in A/C System | ||
| Normal/High | Normal/High | Refrigerant Contamination |
| PAG or POE Oil Overcharge |
A/C Diagnostics Chart
Heating Performance Diagnostic
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Heating system performance. | |||
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual or Go to Symptoms - HVAC Systems - Automatic |
| 2 | Start the engine. Allow the engine to idle. Does the engine reach a normal operating temperature? | Go to Step 3 | Go to Step 9 |
| 3 | Allow the engine to idle. WARNING: Refer to Moving Parts and Hot Surfaces Warning . Select the FLOOR mode. Select the minimum blower speed. Select the warmest temperature setting. Feel the temperature of the inlet and outlet heater hoses at the heater core. Does the inlet heater hose feel warmer than the outlet heater hose? | Go to Step 7 | Go to Step 4 |
| 4 | Install a thermometer into the center IP PANEL air outlet. Secure a thermometer to the heater core outlet hose. Select the PANEL mode. Select the maximum blower speed. Select the warmest temperature setting. Record the temperature at the following locations: The center IP PANEL air outlet The heater core outlet hose Compare the recorded temperatures. Are the two temperature readings about equal? | Go to Step 5 | Go to Step 6 |
| 5 | Inspect and repair the following areas of the vehicle for cold air leaks: The cowl The recirculation door The HVAC module case Perform the necessary repairs. Are the repairs complete? | Go to Step 10 | |
| 6 | Inspect the temperature door operation. Refer to Diagnostic System Check - Vehicle . Perform any necessary repairs. Are the repairs complete? | Go to Step 10 | |
| 7 | Turn OFF the engine. Backflush the heater core. Start the engine. Select the FLOOR mode. Select the minimum blower speed. Select the warmest temperature setting. Feel the temperature of the inlet and outlet heater hoses at the heater core. Does the inlet heater hose feel warmer than the outlet heater hose? | Go to Step 8 | Go to Step 10 |
| 8 | Replace the heater core. Refer to Heater Core Replacement . Is the repair complete? | Go to Step 10 | |
| 9 | Repair the low engine temperature concern. Refer to Engine Fails To Reach Normal Operating Temperature . Is the repair complete? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
| WARNING |
|---|
| Refer to Moving Parts and Hot Surfaces Warning . |
Heating Performance Diagnostic
Noise Diagnosis - Auxiliary Blower Motor
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual or Go to Symptoms - HVAC Systems - Automatic |
| 2 | Sit inside the vehicle. Close the vehicle doors and windows. Turn ON the ignition, with the engine OFF. Cycle the auxiliary blower motor through all of the speeds and modes in order to determine where and when the noise occurs. Is a noise evident during auxiliary blower operation? | Go to Step 3 | Go to Step 10 |
| 3 | Does the noise vary with the auxiliary blower speed? | Go to Step 4 | Go to Step 5 |
| 4 | Inspect for excessive vibration at each auxiliary blower motor speed by feeling the auxiliary blower case. Is excess vibration present? | Go to Step 5 | Go to Step 10 |
| 5 | Remove the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement . Inspect the auxiliary blower motor for deposits of foreign material. Did you find foreign material on the auxiliary blower motor? | Go to Step 7 | Go to Step 6 |
| 6 | Inspect the auxiliary blower motor for the following conditions: Cracked blades A loose impeller retainer Improper impeller alignment Did you find any of these conditions? | Go to Step 8 | Go to Step 9 |
| 7 | Remove the foreign material. Is the action complete? | Go to Step 10 | |
| 8 | Replace the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement . Is the action complete? | Go to Step 10 | |
| 9 | Install the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement . Is the action complete? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
Noise Diagnosis - Auxiliary Blower Motor
Noise Diagnosis - Blower Motor
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual or Symptoms - HVAC Systems - Automatic |
| 2 | Inspect the air inlet grille for debris. Is debris present? | Go to Step 8 | Go to Step 3 |
| 3 | Sit inside the vehicle. Close the vehicle doors and windows. Turn ON the ignition, with the engine OFF. Cycle the blower motor through all of the speeds and modes in order to determine where and when the noise occurs. Is a noise evident during the blower operation? | Go to Step 4 | Go to Step 11 |
| 4 | Inspect for excessive vibration at each blower motor speed by feeling the blower case. Is excess vibration present? | Go to Step 6 | Go to Step 5 |
| 5 | Listen to the blower motor at each speed. Is the blower motor making a squeaking or chirping noise? | Go to Step 9 | Go to Step 11 |
| 6 | Remove the blower motor. Refer to Blower Motor Replacement . Inspect the blower motor impeller for deposits of foreign material. Inspect the blower motor for deposits of foreign material. Did you find any foreign material on the blower motor or blower motor impeller? | Go to Step 8 | Go to Step 7 |
| 7 | Inspect the blower motor for the following conditions: Cracked blades A loose impeller retainer Improper impeller alignment Did you find any of these conditions? | Go to Step 9 | Go to Step 10 |
| 8 | Remove the foreign material. Is the action complete? | Go to Step 10 | |
| 9 | Replace the blower motor. Refer to Blower Motor Replacement . Is the repair complete? | Go to Step 11 | |
| 10 | Install the blower motor. Refer to Blower Motor Replacement . Is the action complete? | Go to Step 11 | |
| 11 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
Noise Diagnosis - Blower Motor
Air Conditioning Compressor Oil Diagnosis
| Condition | Corrective Action |
|---|---|
| NOTE: To avoid repeat compressor failure, always inspect the condition of the refrigerant oil and take the appropriate corrective action before installing the replacement compressor. | |
| Clean Oil no debris present | No corrective action necessary. |
| Clean Oil with debris present | Inspect the suction port of the replacement compressor for presence of a suction screen. If the replacement compressor does NOT contain a suction screen, install suction screen in the line. Replace desiccant or component containing the desiccant. Replace desiccant filter if applicable. Remove and inspect high pressure side filter (if applicable). Remove, inspect, clean or replace orifice tube. If the system has a front orifice tube and is equipped with a filter in the rear auxiliary line, remove, inspect, clean or replace the filter. |
| Dark brown/black and/or pungent/unusual odor with no debris present | Replace desiccant or component containing the desiccant. Replace desiccant filter if applicable. Flush refrigerant system. |
| Dark brown/black and/or pungent/unusual odor with debris present | Replace desiccant or component containing the desiccant. Replace desiccant filter if applicable. Flush refrigerant system. Inspect the suction port of the replacement compressor for presence of a suction screen. If the replacement compressor does NOT contain a suction screen, install suction screen. Remove and inspect high pressure side filter (if applicable). Remove, inspect, clean or replace orifice tube. If the system has a front orifice tube and is equipped with a filter in the rear auxiliary line, remove, inspect, clean or replace the filter. |
| Oil Overcharge | Flush refrigerant system. |
| Refrigerant Contamination | Flush refrigerant system. |
| Hybrid Polyester Refrigerant Oil (POE) Contamination | Flush refrigerant system. Replace desiccant or component containing the desiccant. Replace desiccant filter if applicable. |
| NOTE |
|---|
| To avoid repeat compressor failure, always inspect the condition of the refrigerant oil and take the appropriate corrective action before installing the replacement compressor. |
Air Conditioning Compressor Oil Diagnosis
Noise Diagnosis - Air Conditioning (A/C) System
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Noise originating from the A/C compressor, drive belt or the A/C lines. | |||
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual or Go to Symptoms - HVAC Systems - Automatic |
| 2 | A/C system noises can be generally categorized into three areas: Screeching, squealing, chirping noises Moaning noises Vibration/rattle noises Start the engine. Ensure that the A/C is ON. Is a screeching, squealing noise heard when the A/C is engaged? | Go to Step 3 | Go to Step 9 |
| 3 | With the engine OFF, inspect the drive belt for excessive wear. Refer to Drive Belt Falls Off and Excessive Wear Diagnosis . Is the drive belt excessively worn? | Go to Step 18 | Go to Step 4 |
| 4 | Inspect the drive belt tension. Refer to Drive Belt Tensioner Diagnosis . Is the drive belt tension correct? | Go to Step 5 | Go to Step 19 |
| 5 | Inspect the drive belt for excessive oil coverage. Is the drive belt covered with oil? | Go to Step 17 | Go to Step 6 |
| 6 | Start the engine. Ensure that the A/C is ON. Inspect the compressor and the clutch. Is the A/C compressor locked up? | Go to Step 24 | Go to Step 7 |
| 7 | Is the A/C compressor clutch slipping? | Go to Step 23 | Go to Step 8 |
| 8 | WARNING: Refer to Moving Parts and Hot Surfaces Warning . Using a stethoscope, listen to the A/C compressor for any abnormal noises.Is the compressor causing an abnormal noise? | Go to Step 15 | Go to Step 10 |
| 9 | Does a moaning noise exist when the A/C clutch is engaged? | Go to Step 10 | Go to Step 12 |
| 10 | Listen to the A/C compressor components and mounting for noise concerns using a stethoscope. Are any of these components loose, damaged or excessively worn? | Go to Step 20 | Go to Step 11 |
| 11 | Idle the engine. Engage the A/C compressor clutch. Using a stethoscope, move around the entire refrigerant plumbing system. Listening for any abnormal noises caused by a component of the A/C system touching another component. Are any of the A/C components grounding out and causing a vibration noise? | Go to Step 22 | Go to Step 13 |
| 12 | Does a vibration or rattle noise exist when the A/C clutch is engaged? | Go to Step 13 | Go to Step 14 |
| 13 | Does the noise stop when the A/C clutch is disengaged? | Go to Step 15 | Go to Step 25 |
| 14 | Idle the engine in PARK with the A/C compressor clutch engaged. Using a stethoscope, move around the entire A/C system testing for any abnormal noises caused by a component. Do any of the A/C components cause an abnormal noise? | Go to Step 21 | Go to Step 25 |
| 15 | Verify that the A/C system is properly charged. Refer to Refrigerant System Specifications . Is the A/C system properly charged? | Go to Step 26 | Go to Step 16 |
| 16 | Recharge the A/C system to specification. Refer to Refrigerant Recovery and Recharging . Is the abnormal compressor noise still present? | Go to Step 24 | Go to Step 26 |
| 17 | Repair the oil leak. Refer to Oil Leak Diagnosis . Is the repair complete? | Go to Step 18 | |
| 18 | Replace the drive belt. Refer to Drive Belt Replacement . Is the replacement complete? | Go to Step 26 | |
| 19 | Replace the drive belt tensioner. Refer to Drive Belt Tensioner Replacement . Is the replacement complete? | Go to Step 26 | |
| 20 | Repair or replace the A/C compressor mounting component. Is the repair complete? | Go to Step 26 | |
| 21 | Repair or replace the component which is causing the moaning concern as needed. Is the repair complete? | Go to Step 26 | |
| 22 | Correctly route or insulate the A/C component. Is the repair complete? | Go to Step 26 | |
| 23 | Replace the A/C compressor clutch. Refer to Air Conditioning Clutch Assembly Replacement . Is the repair complete? | Go to Step 26 | |
| 24 | Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement . Is the repair complete? | Go to Step 26 | |
| 25 | The concern may be caused by an engine related component. Refer to Vibration Analysis - Engine . Did you find and correct the condition? | Go to Step 26 | |
| 26 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
| WARNING |
|---|
| Refer to Moving Parts and Hot Surfaces Warning . |
Noise Diagnosis - Air Conditioning (A/C) System
Noise Diagnosis - HVAC Module
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual or Go to Symptoms - HVAC Systems - Automatic |
| 2 | Start the engine. Cycle through all of the following: Blower motor speeds HVAC modes Temperature control settings Determine the type of noise: Scrape, pop Tick/click, chirp or groaning Air rush/whistle Is a scrape or pop noise evident when selecting modes or temperature settings? | Go to Step 6 | Go to Step 3 |
| 3 | Is a tick/click, chirping, groaning or scraping noise present, but decreases as blower motor speed is decreased? | Go to Step 6 | Go to Step 4 |
| 4 | Is an air rush/whistle noise evident in all modes but not all temperature settings? | Go to Step 6 | Go to Step 5 |
| 5 | Is an air rush/whistle noise evident only in defrost or floor mode? | Go to Step 6 | Go to Step 6 |
| 6 | Remove the instrument panel I/P carrier. Refer to Instrument Panel Carrier Replacement . Is the action complete? | Go to Step 7 | |
| 7 | Inspect the air flow doors for proper operation. Inspect the ducts for obstructions or foreign materials. Were any of these conditions found? | Go to Step 10 | Go to Step 8 |
| 8 | Inspect the mode and temperature doors and seals for warping or cracking. Are the doors in normal condition? | Go to Step 11 | Go to Step 9 |
| 9 | Replace the appropriate door and/or seals. Is the repair complete? | Go to Step 11 | |
| 10 | Remove any obstructions or foreign material found. Is the action complete? | Go to Step 11 | |
| 11 | Install the I/P carrier. Refer to Instrument Panel Carrier Replacement . Is the action complete? | Go to Step 12 | |
| 12 | Operate the system to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
Noise Diagnosis - HVAC Module
Odor Diagnosis
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Odor originating or noticed through the HVAC system. | |||
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual or Go to Symptoms - HVAC Systems - Automatic |
| 2 | Sit inside the vehicle. Close all of the doors and windows. Start the engine. Allow the engine idle at normal operating temperature. Select the maximum blower speed. Select the PANEL air outlet mode. Select the coldest temperature setting. Cycle through all of the blower speeds, modes and temperatures to define what type of odor is present. Musty smell Coolant smell Oil smell Does the odor have a musty smell? | Go to Step 3 | Go to Step 8 |
| 3 | Inspect the HVAC filter and the air inlet grille for debris. Is debris present? | Go to Step 4 | Go to Step 5 |
| 4 | Remove any debris. Is the action complete? | Go to Step 15 | |
| 5 | Inspect for wet carpeting. Is the carpet wet? | Go to Step 6 | Go to Step 14 |
| 6 | Inspect for the following conditions: Water leaks around the windshield Blockage of the HVAC module drain Leaks around the door seals Is a leak present? | Go to Step 7 | Go to Step 14 |
| 7 | Repair the leak as necessary. Is the repair complete? | Go to Step 15 | |
| 8 | Does the odor have a coolant smell? | Go to Step 9 | Go to Step 12 |
| 9 | Inspect the cooling system for leaks. Refer to Loss of Coolant . Is a leak present? | Go to Step 10 | Go to Step 12 |
| 10 | Inspect for coolant leaking inside the vehicle or for a film build-up on the windshield. Is the condition present? | Go to Step 11 | Go to Step 15 |
| 11 | Replace the heater core. Refer to Heater Core Replacement . Is the repair complete? | Go to Step 15 | |
| 12 | Does the odor have an oily smell? | Go to Step 13 | Go to Step 15 |
| 13 | Inspect the engine compartment for any leaks. Refer to the following procedures: Oil Consumption Diagnosis Fluid Leak Diagnosis Repair any oil leaks. Is the repair complete? | Go to Step 15 | |
| 14 | A musty odor can be caused by mold or mildew build-up on the evaporator or the heater core or inside of the HVAC module. Refer to Odor Correction . Is the action complete? | Go to Step 15 | |
| 15 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
Odor Diagnosis