Many of us come to a conclusion that if the vehicle's AC fails to blow crisp, cool air, the cause is a malfunctioning AC Compressor. This may not turn out to be true all the time, as the AC could have failed due to a fault in some other component. Therefore, instead of leaping to a wrong conclusion, it is better to ascertain if your AC compressor is really at fault. You can check your pressure readings against the infographic above/chart below to narrow down the problem and remedy for your AC Compressor.
| AC Compressor Pressure | Problem with the Compressor | Remedy |
|---|---|---|
| High 250 Low 50
| Overcharged system or condenser issue | Recharge system and inspect condenser for blockage |
| High 160 Low 10
| Evaporator frosted or low pressure piping faulty, or expansion valve | Check and replace as required |
| High 225 Low 80
| Expansion valve too wide open, heat sensitizing tube faulty, or too much refrigerant | Recharge system |
| High 50 Low 50
| Clutch engages then disengages | Check wiring, run power straight to the compressor to test |
| High 150 Low 30
| Water in the system | Evacuate for 30 mins, dry and refill |
| High 125 Low 30
| Not recharged enough or too much oil | Check amount of refrigerant/oil |
| High 150 Low 30
| Ideal reading | Ideal reading |
| High 200 Low 70
| Blockage in system | Find blockage and replace |
| High 150 Low>10
| Expansive valve open or leak | Check valve or complete dye test |
| High 100 Low 100
| Compressor does not engage | Check wiring |
Note: The most ideal pressure readings are around 150 high and 30 low.
Warning: Remember, venting 134a refrigerant into our atmosphere is illegal and bad for our environment.
The following table presents the possible inferences and the actions that can be taken, based on the level of pressure registered by the high and low pressure gauges:
| Low Pressure Gauge | High Pressure Gauge | Inference/Action Required |
|---|---|---|
| In range | In range | AC is working properly |
| Low | Low | Add refrigerant |
| Low | High | Need service, possibly blockage of the expansion valve or orifice tube |
| High | Low | Need service, possibly faulty compressor |
| High | High | System is overcharged. Slowly remove refrigerant. Venting is illegal in USA |
