A/C Diagnostics Chart
WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
| A/C System Concern | Potential Causes | |
|---|---|---|
| Compressor Inoperative | Electrical Wiring Issue | |
| No or Low Refrigerant Charge | ||
| Compressor Internal Malfunction | ||
| Compressor Clutch Malfunction | ||
| A/C Pressure Sensor Malfunction | ||
| Evaporator Air Temperature (EAT) Malfunction | ||
| HVAC Controls Malfunction | ||
| Low Side Gauge Reading | High Side Gauge Reading | Potential Causes |
| Same as High Side | Same as Low Side | No or Low Refrigerant Charge |
| Compressor Malfunction | ||
| A/C Pressure Sensor Malfunction | ||
| EAT Malfunction | ||
| HVAC Controls Malfunction | ||
| Normal | Normal | Temperature Actuator Malfunction |
| Temperature Door Malfunction | ||
| Low | Low | Low Refrigerant Charge |
| Restriction between the Compressor Outlet and Low Side Port | ||
| Low/Normal | Evaporator Freezing/EAT Malfunction | |
| High | Compressor Stuck at Maximum Displacement/EAT Malfunction | |
| Normal/High | Normal/High | PAG or POE Oil Overcharge |
| High | Low | Restriction between the Low Side Port and Compressor Inlet |
| Expansion Device Stuck Open | ||
| Compressor has Low Displacement or Internal Malfunction | ||
| High | Malfunctioning Cooling Fans | |
| Refrigerant Overcharge | ||
| Restricted Condenser Air Flow | ||
| Air in A/C System | ||
|
NOTE:
Restrictions can occur in any part of an A/C system and may result in various gauge pressure values, depending on the system design and service port locations. The use of a non-contact, infrared thermometer can help diagnose a restricted A/C system with the ability to quickly observe significant, unexpected temperature changes in components and plumbing due to debris, contamination, pinched/damaged hoses, etc. |
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