How Vehicle Air Conditioning Works.

A BRIEF GUIDE TO HOW VEHICLE AIR CONDITIONING SYSTEMS WORK.

There are two "sides" to the air conditioning system, a low pressure side and a high pressure side. On the high pressure side, low pressure R134a vapour entering the compressor is compressed to become high pressure/temperature R134a vapour. This is then circulated along with lubricant oil to the condenser. As the high pressure/temperature vapour travels through the condenser, heat is released to the cooler ambient air passing over the condenser tubes condensing the vapour into a liquid. This high pressure/temperature liquid then travels through the filter drier onto the expansion valve where a small variable orifice provides a restriction against which the compressor pushes.

On the low pressure side, suction from the compressor pulls the high pressure/temperature liquid R134a through the small variable orifice of the TX valve and into the low-pressure side of the A/C system. The R134a is now a low pressure/temperature vapour where heat from the cabin being blown over the evaporator coil surface is absorbed into the colder low pressure refrigerant The R134a is then pulled through the evaporator and into the compressor. The A/C cycle begins again as the R134a vapour is compressed and discharged under pressure.

To summarise, R134a in the LOW-PRESSURE side is COLD and can absorb large quantities of heat from the air moving over the evaporator. R134a in the HIGH-PRESSURE side is HOT and the cooler ambient air moving over the condenser can absorb the heat from it.

Vehicle Specific Information

• Porsche Condensers

• Qashqai J11 / X-Trail T32

• Renault Trafic 3 / Vivaro B

Tips and Advice

• Changing Porsche Condensers

• Leaking Condensers

• Checking the A/C on a car you're buying

• Don't suffocate your A/C system!

• How to change a pollen filter

• How to stop those steamy windows

• A/C not cold enough - 3 case studies

Testimonials

"My Freelander's air conditioning hadn't worked for a couple of years. I thought it was a major costly job to resolve so never tried to repair it. After seeing an advert for Mr Cool I decided to call him in. Turns out it just needed re-gassing! Mr Cool sorted it very proficiently and professionally and my air con has worked ever since. I would not hesitate in recommending Mr Cool to anyone." - Graham Turner, Ashbourne.

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