More NUMBERS....

[wwest]

'88 Porsche Carrera, several quick spins around the block...A/C full on, windows wide open. Throughout the test the compressor clutch was always engaged except with ignition off. Idle speed was 800 RPM.

87F OAT, 35% Rh, BRIGHT sunshine,

1st digital temperature probe covered with thermal conductive paste inserted into passenger side center cylinder cooling fins from exhaust side (RECTAL, as it were).

5 trial cycles, average was 271F heater fan off, 264F heater fan on.

2nd digital temperature probe inserted into condensor fins from topside.

135F heater fan off, 125F heater fan on.

3rd digital probe inserted in a drilled hole in the engine fan shroud just behind (I hope) the alternator. ~140F throughout(***) the above testing but rose to 185F within a minute of switching ignition off. Still at 174F 20 minutes later.

*** I suspect engine radiant heat was the dominant factor here, plus no direct "benefit" from heater fan airflow cooling the exhaust manifold.

Draw your own conclusions.