Refrigerant Leak Testing
Note. All A/C system repairs must be verified using electronic leak detection. Dye detection may take up 2 or 3 days to be reliable.
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 refrigerant oil throughout the refrigerant system.
Verifying some passive leaks may require using the GE-50078 Infrared Refrigerant 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. Excessive dye can result in compressor damage.
Visual Inspection
Visually trace the entire refrigerant system and look for signs of lubricant leakage, damage, and corrosion on all lines hoses and components (Oil can be an indication of a leak). Each questionable area should be checked for leaks using an electronic leak detector.
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 - 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. Refer to PASSENGER COMPARTMENT AIR FILTER REPLACEMENT . 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 LEAK DIAGNOSIS for the 3.0L LF1engine or for the 2.8L LAUL engine POWER STEERING FLUID LEAKS . 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 |
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 | |
| 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 |
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 - 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 | 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 I/P 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 I/P PANEL air outlet The heater core outlet hose Compare the recorded temperatures. Are the 2 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. Back-flush 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 |
Noise Diagnosis - Auxiliary Blower Motor
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Noise originating from the auxiliary blower motor. | |||
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to DIAGNOSTIC SYSTEM CHECK - VEHICLE |
| 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 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 12 |
| 3 | 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 4 |
| 4 | Listen to the auxiliary blower motor at each blower speed. Is the auxiliary blower motor making a squeaking or chirping noise? | Go to Step 10 | Go to Step 12 |
| 5 | Inspect the blower motor and the blower motor housing for proper installation. Is the blower motor or the blower motor housing touching the vehicles body and causing the vibration? | Go to Step 9 | Go to Step 6 |
| 6 | Remove the auxiliary blower motor. Refer to AUXILIARY AIR CONDITIONING BLOWER MOTOR REPLACEMENT . Inspect the auxiliary blower motor impeller for deposits of foreign material. Inspect the auxiliary blower motor for deposits of foreign material. Did you find foreign material on the auxiliary blower motor? | Go to Step 8 | Go to Step 7 |
| 7 | 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 9 | Go to Step 11 |
| 8 | Remove the foreign material. Is the action complete? | Go to Step 11 | |
| 9 | Install the component so there is no contact with the vehicles body. Is the action complete? | Go to Step 12 | |
| 10 | Replace the auxiliary blower motor. Refer to AUXILIARY AIR CONDITIONING BLOWER MOTOR REPLACEMENT . Is the repair complete? | Go to Step 12 | |
| 11 | Install the auxiliary blower motor. Refer to AUXILIARY AIR CONDITIONING BLOWER MOTOR REPLACEMENT . Is the action complete? | Go to Step 12 | |
| 12 | 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
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Noise originating from the blower motor. | |||
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to |
| 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 |
Air Conditioning Compressor Oil Diagnosis
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.
| Condition | Corrective Action |
|---|---|
| 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. If the system has a front orifice tube and is not equipped with a filter in the rear auxiliary line, remove the filter in the auxiliary TXV and Install a universal inline A/C Filter P/N 89016656 (AC Delco P/N 15-10413) as close to the rear TXV as possible. |
| 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. Refer to FLUSHING |
| 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. Refer to FLUSHING 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. If the system has a front orifice tube and is not equipped with a filter in the rear auxiliary line, remove the filter in the auxiliary TXV and Install a universal inline A/C Filter P/N 89016656 (AC Delco P/N 15-10413) as close to the rear TXV as possible. |
| Oil Overcharge | Flush refrigerant system. Refer to FLUSHING |
| Refrigerant Contamination | Flush refrigerant system. Refer to FLUSHING |
| Hybrid Polyolester Refrigerant Oil (POE) Contamination | Flush refrigerant system. Refer to FLUSHING Replace desiccant or component containing the desiccant. Replace desiccant filter if applicable. |
Noise Diagnosis - Air Conditioning (A/C) System
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to SYMPTOMS - HVAC SYSTEMS - AUTOMATIC |
| 2 | A/C system noises can be generally categorized into 3 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 ON? | Go to Step 3 | Go to Step 6 |
| 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 14 | 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 15 | Go to Step 5 |
| 5 | Inspect the drive belt for excessive oil coverage. Is the drive belt covered with oil? | Go to Step 13 | Go to Step 6 |
| 6 | Start the engine. Ensure that the A/C is ON. Is the compressor locked up? | Go to Step 19 | Go to Step 7 |
| 7 | Using a stethoscope, listen to the A/C compressor for any abnormal noises. Is the compressor causing an abnormal noise? | Go to Step 11 | Go to Step 8 |
| 8 | 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 16 | Go to Step 9 |
| 9 | Idle the engine. Engage the A/C. Using a stethoscope, move around the entire refrigerant plumbing system, inspecting for any abnormal noises caused by component ground-out. Are any of the A/C components grounding out and causing a noise? | Go to Step 21 | Go to Step 10 |
| 10 | Idle the engine in PARK with the A/C on. 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 17 | Go to Step 20 |
| 11 | Verify that the A/C system is properly charged. Refer to REFRIGERANT SYSTEM SPECIFICATIONS . Is the A/C system properly charged? | Go to Step 19 | Go to Step 16 |
| 12 | Recharge the A/C system to specification. Refer to REFRIGERANT RECOVERY AND RECHARGING (BELT DRIVEN COMPRESSOR) . Is the abnormal compressor noise still present? | Go to Step 20 | Go to Step 21 |
| 13 | Repair the oil leak. Refer to the appropriate engine repair procedure. Is the repair complete? | Go to Step 21 | |
| 14 | Replace the drive belt. Refer to DRIVE BELT REPLACEMENT . Is the replacement complete? | Go to Step 21 | |
| 15 | Replace the drive belt tensioner. Refer to DRIVE BELT REPLACEMENT . Is the replacement complete? | Go to Step 21 | |
| 16 | Repair or replace the A/C compressor mounting component. Is the repair complete? | Go to Step 21 | |
| 17 | Repair or replace the component which is causing the moaning concern as needed. Is the repair complete? | Go to Step 21 | |
| 18 | Correctly route or insulate the A/C component. Is the repair complete? | Go to Step 21 | |
| 19 | Replace the A/C compressor. Refer to A/C COMPRESSOR, REPLACEMENT (LF1) or A/C COMPRESSOR, REPLACEMENT (LAU) . Is the replacement complete? | Go to Step 21 | |
| 20 | 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 21 | |
| 21 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
Noise Diagnosis - HVAC Module
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Noise originating from the HVAC module. | |||
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | 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 TIE BAR 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 TIE BAR REPLACEMENT . Is the action complete? | Go to Step 12 | |
| 12 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |