Testing automotive A/C systems for peak performance

[b5blue]

   In this link, if you scroll down a bit is what looks like good procedure for adjusting Freon level for peak efficiency. It involves "super heat and super cool readings" and I'd like opinions from real world mechanics if the procedure is sound. Thanks in advance
   https://mechanics.stackexchange.com/questions/31874/what-temperature-should-the-a-c-blow

[John_Kunkel]

I've heard of the superheat test on home HVAC systems but not on cars.

I believe that the factory designed the systems to have a specific charge by weight and that's sufficient for best performance.

[c00nhunterjoe]

Overthinking it as john stated. Run the factory weight. To "test " it without gauges, the low side line near the accumulator should be beer can cold.

[b5blue]

Yea I've gauges and temp probes/guns a digital scale also. The heat and humidity are kicking in down here so I was wanting to max out.

[Bronzedodge]

Oh boy.   So, while sub cooling and superheat is standard in residential, commercial, and industrial systems, and can often be compared to published specs; the factory didn't spec it that way, as John and Joe said.   The FSM is actually very good in it's procedures.  The tricky part is measuring wet bulb temperatures.  Sling psycrometers are getting difficult to find, and electronic humidity meters often just express in % humidity.   

My advice is to make sure that the system is leak free first.   The shaft seal on s tricky to test unless under pressure, and is often a leak point on an older system.    Oil the threads on any fittings and gaskets.   A refrigerant scale and someone who knows how to weigh in the charge are a plus.   

[John_Kunkel]

The sad truth is that the compressor seal is the weak link in car A/C systems. At its best, the seal will leak a little and this skews any attempt to adjust the charge by the superheat method. Home HVAC systems are hermetically sealed and should never leak.

[b5blue]

The compressor on my 07 Dakota is 9 years older than my 70 Chargers Classic Auto Air system.