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Pressure switches and switches














Pressure switches are responsible for protecting the air conditioning system against damage caused by too high or low pressures. There are low pressure switches, high pressure switches and trinary switches. The trinary switch comprises the high pressure switch, low pressure switch and an additional switch contact for the condenser fan.


How they work

The pressure switch (pressure monitor) is normally installed on the high pressure side of the air conditioning system. In the case that the pressure is too high (approx. 26-33 bar) it switches the power supply to the compressor clutch off. If the pressure is too low (approx. 2 bar), the power supply is interrupted as well in order to avoid compressor damage due to insufficient lubrication. The third switch contact in the trinary switch controls the electrical condenser fan in order to ensure optimum refrigeration condensation in the condenser.


Effects of failure

A defective or failing pressure switch can manifest itself as follows:

  • Insufficient cooling performance
  • Frequent switching on and off of the compressor clutch
  • Air conditioning system without function.


There are a number of possible causes of failure:

  • Contact fault at electrical connections
  • Contaminations in the system
  • Damage to the housing caused by vibrations or accidents 

Air Conditioning Component: Pressure Switches and Switches- Houston's Premier Auto Repair Facility

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The air conditioning is a complex system and understanding the reason something failed is just as important as fixing the car itself. Bring your vehicle today so it may be examined by an ASE Certified Technician in Heating and Air Conditioning. We have the latest EPA compliance equipment to inspect your vehicle's Heating, Ventilation, and Air Conditioning System. The benefits of having a certified technician with the proper tools for examining your vehicle include finding the source of the problem AND the important WHY something failed. Pinpointing the source of the failure and why helps resolve the problem for good versus running into the same issue later. Our staff can provide insight and tips on how to prevent costly repairs in the future. 


Majority of air conditioning and heating repairs can often be prevented with routine maintenance or by bringing the vehicle into the auto shop at the moment you begin to notice your air conditioning or heater not performing normally. Whether you notice the car A/C not to be cooling like it used to and having a performance issue or wet spots appearing, odd, sweet or bitter smells, or irregular noises that you recently noticed -- bring the vehicle to the shop so it may be inspected by a certified professional so they can discover the cause of the inefficient air conditioning or heating performance. 


Have your vehicle checked by an ASE Certified Technician in Heating & Air Conditioning. 

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