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Automotive AC technicians use numerous diagnostic techniques to determine the cause of air conditioning problems. The refrigerant pressure in your system is one critical factor that repair techs will consider during any diagnostic process. Since your car's HVAC components rely on precise pressure levels, any variation from manufacturer specifications can often lead to problems.
Checking refrigerant pressure isn't as straightforward as reading a dipstick, however. Repair shops use a tool known as a pressure manifold gauge, something you may have also seen home HVAC technicians utilize. These tools are necessary since technicians need to consider both static and dynamic pressure on your system's low and high sides.
Low vs. High and Static vs. Dynamic
All air conditioning systems work on the same general principle. Your compressor pressurizes hot refrigerant, which then releases its heat in your condenser coils. This action occurs on the "high" side of your system. The cooled refrigerant passed through to the "low" side, where it absorbs cabin heat before returning to the compressor to restart the process.
When your system is running, the refrigerant should be under higher pressure on the high side than on the low side. These are "dynamic" pressure readings since they'll change as the system runs and the compressor engages and disengages. On the other hand, you take "static" pressure readings with the system turned off. These readings should be the same on both the low and high sides of the system.
What Does Static Pressure Tell You?
Static pressure helps diagnose a few common issues with automotive AC systems. Still, it requires more understanding of AC principles than simply reading a number since pressure can vary with temperature. For trained techs, static pressure can be the first indication that a system is undercharged or overcharged. Likewise, uneven static pressure can indicate a clog preventing pressure from equalizing.
What Does Dynamic Pressure Tell You?
Dynamic pressure provides more detailed diagnostic information. Typical automatic AC systems use a low-side pressure switch to check the pressure on the low side of the system. When the pressure reaches a certain level, the compressor turns on, which causes pressure to increase on the high side and decrease on the low side. When the pressure falls, the switch opens, and the compressor disengages.
AC techs can use this information to diagnose the low-side pressure switch, compressor clutch, compressor, refrigerant levels, and numerous other components. For example, dynamic pressure can alert a technician that your compressor may be failing if the clutch engages and the pressure on both sides remains relatively stable.
Ultimately, AC technicians rely on reading both static and dynamic pressure to determine why your AC system might not be working. These diagnostic techniques are crucial to finding the underlying source of the problem and ensuring an effective and permanent repair.
Reach out to a mechanic who offers auto AC repair services to schedule an appointment.
Share30 November 2021
