Chasing AC outlet temperature numbers

["Cadillac Kid" Greg Surfas 15364]

Was on a few errands yesterday in my 75 DeVille. The cabin was quite comfortable, but when I reached out and felt the dash outlet air temperature it was not really cold.What's wrong I thought? I put my thermometer in the outlet and it read 61.6 degrees. That's warm I thought. Then I realized that the outside temperature was 104 degrees and the humidity was about 60%. and when I got home went to the temperature (outside vs AC) matrix in the FSM. At the conditions of 104/60% the FSM says that I should expect 62.5 degrees out the vent. I think this is the first time I have been in one of my cars at these temperature extremes, and as I said initially the cabin was comfortable without any cold drafts, excessive fan noise, or water dripping off the glass. It reinforces my opinion that the engineers at Cadillac (Harrison or Frigidaire) really knew their field.
Greg Surfas

[Cadillac Jack 82]

I know that my 55 will pump out 29 degrees from the rear vents but it only keeps it cool when its that hot outside.

["Cadillac Kid" Greg Surfas 15364]

Tim
29 degrees is great but unless you are in the middle of the Sahara Desert, that 3 degrees below freezing (of water) will lead to an iced up coil and blocked up air flow in a very short time.
Greg Surfas

[Seville Life]

What 'matrix' are you using? Who wrote it?

["Cadillac Kid" Greg Surfas 15364]

The Temperature vs AC conditions graph in the FSM
Greg Surfas

[Chopper1942]

The following are AC performance specs for a 73 Chevy Silverado with A6 compressor and an expansion tube to control liquid to the evaporator (changes high pressure liquid to low pressure liquid).

Four Season Systems (Refrigerant Charge = 3 Lbs.)  R 12

Engine rpm 2 0 0 0

Temperature of          
Air Entering Condenser        70° 80° 90° 100° 110° 120 °

Compressor Head Pressure          145 185 200 215  255    285                            
                                  155 195 210 225  265  295

Discharge Air Temp         38 38  40   41   43   48
at Right Hand Outlet         41 41  43   44   46   51

A 2017 Escalade AC system with R-1234yf at 96-105 with above 40% humidity left center outlet temp 75 degrees.
Same vehicle with R-134a at same temp and humidity 79 degrees.

"Cadillac Kid's" temps and performance charts are much better.  The 75 performance chart is using R-12.  Why would any one want to spend all the money to convert to R-134a when it won't perform as well!

My 73 Chevy Crew Cab and 79 El Dorado both have R-12 and always will.

Stay Kool.