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  • Writer's pictureBilly Hillmuth

AC not working? What’s the deal?

Updated: Jul 24, 2021

Over time, your car’s air conditioning system will begin to be less effective. Then one day when you turn the knob in the summer heat the air is warm.

The Basics

Your cars Air Condition works on a fairly simple principle. The AC components on your vehicle are the following:

  1. Compressor

  2. Condensor

  3. Belt

  4. Evaporator

  5. Liquid and Gas Lines

  6. Relays

  7. Sensors

  8. Blower Motor & Regulator

  9. Climate Control Unit

  10. Air Ducts

  11. Blend doors

  12. R134a or R1234YF (refrigerant)

All of the components above relate to mechanical and electrical components that could cause your AC system to not function. Most of the time your AC stops working due to a leak of Refridgerent that causes problems. The system is pressurized and a closed system, if the system loses refrigerant you need to find the leak and replace the worn component and ReTest.

How does your AC work?

The evaporator, located inside the passenger compartment, pulls air from the cabin across a set of coils filled with refrigerant. As it absorbs heat, refrigerant takes on a gaseous form, and it is then passed through a compressor. The compressor pressurizes the refrigerant, turning it from a gaseous state into a liquid form. The pressurized liquid chemical is passed through a condenser, and the heat moves from the liquid and into the air. After the chemical moves through the evaporator, the moisture is reduced, and the system collects and drains the condensate. The entire process is repeated, and the humidity and warmth are gradually drawn out of the cabin of the vehicle, and replaced with cool air.

How much refrigerant leakage is normal?

A/C systems are nearly airtight, but they are not completely airtight. Refrigerant is in a liquid form when it is pressurized inside the car’s A/C system, and it is always trying to push its way out. When it leaks out, it is in the form of a colorless gas, and due to its structure, you won’t be able to see it or hear it.

Will, it hurt to keep running an A/C system that blows warm air?

Yes. If your A/C system blows warm air, it will lose a lot of refrigerants. These chemicals are mixed with lubricating oil, and responsible for keeping the compressor operating smoothly. As a result of losing a lot of refrigerants, your system will be running too dry, and if it is not properly lubricated, your compressor can burn out. Since most refrigerants mix in a UV-sensitive dye, if they evaporate away, the dye will leave a traceable stain, and using an ultraviolet light near the A/C will show where the leak is.

Why retest the system after the repairs are completed?

After repairs are made we retest the system to verify there are no additional areas causing the AC system, not to function. In some cases, after replacing the worn components and pressurizing the system the next weakest link is revealed, and then that component needs replacement. If the system has the right amount of Refrigerant, and the pressures are good, we could be dealing with an electrical issue. This will cause additional diagnoses to identify the problems. Bottom line AC Repairs can be frustrating, expensive, and difficult to properly diagnose. However, at Hillmuth our Mechanics are MACS Certified which means you’re in good hands knowing that you will save money and time by receiving the proper diagnoses and repair.

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