A/C

 By Brandon Baldwin

It’s summer and we humans have a narrow comfort level for temperature.  Comfort in our cars is no different.  Most of us are old enough to remember when not all cars came with AC, so to remove heat, we opened the windows.  But, AC started in cars probably earlier than you’d think.

The 1939 Packard was the first car to have air conditioning, followed by Cadillac in 1941.  Most early systems we are familiar with used R12 for refrigerant which is a CFC that works extremely well due to it’s large mass and stability.  You needed a mineral based oil in the system too.  The refrigerant in every system carries the oil throughout the system.  Therefore, you need a precise amount of the refrigerant and a precise amount of oil for it to work it’s best.  The good part about R12 is how well it worked and that if it leaked, it carried some of the oil with it to the exterior parts.  This makes it easier to find the leaks than R12′s replacement: R134a.

Conversions took place in the 1990′s since R12 depletes the ozone quickly.  R134a needs a little more area to perform as well as R12 and leaks a little easier due to the smaller molecule, and the PAG oil is water soluble.  That makes the leak harder to find since rain and other splashes the car goes through will wash away the oil.  This is actually normal for a pound of R134a to escape from the system every 7 years.  Yes, you can recharge it, but it’s best to have it done with a set of gauges to read the high and low side pressures with a refrigerant machine rather than the canisters.  And, for those of us  who  do  this, legally, we need to have a refrigerant handling license.   We  even  have  a  refrigerant identifier since some fly-by-night suppliers will mix propane, butane, or CO2 with the refrigerant to lower their cost since these products cost less.  But, these do harm to the system and if you didn’t notice, some of them are flammable.  If you rear-end another car, the first thing behind the bumper is NOT the radiator but the condenser for the AC.  Do you feel comfortable having these gases out front?

Anyway, if you should decide to convert at some point from R12 to R134a, to the newest refrigerant HFO-1234yf which came out in 2011, you will need to  consult the  manufacturer to see what other parts need to be replaced.  Most filter dryers or receivers hold the most oil, and therefore, are commonly replaced with any upgrade.  Keep in mind also, that the R134a oil is  even  hydroscopic,  which  means it  will  pull  moisture out of the air if exposed to it.  The result is a corrosive compound.  I know that I will need to replace all my AC parts in the car I’m working on now since the system has been open for years.  Maybe I’ll just run the belt a different route to skip the compressor, to save money; the windows still operate anyway.