AUTO AIR CONDITIONING
An In-Depth Look
Air conditioning has a language all its own and oftentimes mechanics forget that their customers simply aren’t accustomed to it. Therefore, we’ve prepared this primer for you, so whether you come to us here at Cap-A Radiator in Farmingdale Long Island – or to someone else – you’ll at east understand the basics of what’s happening.
A/C Service Terms:
Evacuate- Pull a vacuum on the system. This removes air from the system. Air has moisture and takes up space. Putting refrigerant into a system without pulling out the air first will cause high pressures and poor (if any) cooling.
Recharge- Injecting refrigerant into a previously evacuated A/C system. Refrigerant can be put into the high-pressure side as a liquid prior to starting the engine and engaging compressor. After the engine is running, it must be put in thru the low-pressure side slowly. Always measure how much you have put in.
Recover- Taking the refrigerant out of the system and putting it into a can for filtering and using it over again. It should not be discharged into the atmosphere.
Main Components of your Air Conditioning System:
We want to put an end to your air conditioning problems. A basic knowledge of your car’s A/C system will help you understand what must be done to restore your air conditioner to peak performance.
The COMPRESSOR is essentially the "motor" of the A/C system. It pumps the refrigerant through the system and compresses it from a low temperature, low pressure gas to a high temperature, high pressure liquid. The compressor also pumps the freon through the system.
The CONDENSER sets in front of the radiator. This is where the refrigerant is cooled by being condensed from a gaseous form back to a liquid form. The heat that is subsequently generated in the condenser by this process is then cooled by dissipation through the condenser's fins and blown off by the engine cooling fan(s).
The EVAPORATOR, located inside the passenger compartment, just inside the firewall, is where the refrigerant evaporates from a liquid form back into a gaseous form. As the refrigerant evaporates, it draws in heat and removes it from the atmosphere. That hot gas is pumped to the condenser, where it will be turned back into a liquid and cooled off.
The ORFICE TUBE or THERMAL EXPANSION VALVE regulates the liquid refrigerant going into the bottom of the evaporator. Actually acts as a restrictor to the flow of the liquid refrigerant. CCOTs (Clutch Cycling Orifice Tubes) essentially replaced TX valves long ago.
The ACCUMULATOR or RECEIVER/DRIER: An accumulator filters the refrigerant when it is in a gaseous state. A receiver/drier filters the refrigerant when it is in a liquid state. Most manufacturers converted from receiver/driers to accumulators in the 1970s and 1980s.
REFRIGERANT is more commonly known by the generic term “freon” and is the gas/liquid which passes through all the components in the A/C system and draws heat and moisture from the passenger compartment. Freon (R12) was used for over 50 years, but was found to be causing a hole in the Ozone layer of Earth’s atmosphere and while duPont switched to “Suva” (HFC-134a), people continued to call all refrigerants “freon.”
Today, the majority of automakers are using HFO-1234yf refrigerant, a product co-developed by duPont and Honeywell, now being made in both China and the United States by Honeywell. 1234yf is a vast improvement over 134a in the area of ozone protection. Although Mercedes Benz once comcludd that the product was flammable, further research proved that the conditions for 1234yf to ignite a fire were nearly impossible to replicate in the real world.
CHARGE PORT / SCHRADER VALVE: Refrigerant is installed into the system through the low-pressure port. The high-side port serves to keep a check on the high-end pressure as the system is being serviced. Once the service is over, the Schrader valves serve no purpose until the next maintenance.
The COMPRESSOR CLUTCH engages
and disengages the compressor.
REFRIGERANT OIL lubricates the air conditioning system and prevents the compressor from grinding to a halt.
HOSE ASSEMBLY: A combination of rubber and steel or aluminum pipes through which the refrigerant passes between the other major components.
A CLUTCH CYCLING SWITCH regulates the operation of the compressor depending on system pressures or temperatures.