1991 Volvo 240 Sedan, Automatic, 116k +/- miles

Noticing my idle does not change when I engage the air conditioning as
stated in the Bentley manual (775rpm to 900rpm) I applied their test
procedure to verify the AC microswitch and AC compressor signal are in
working order.

According to "Table f. LH-2.4 and LH-3.1 System Electrical Tests" page 214-
15 (second from last item on the table) I should be getting approximately
10 ohms with the AC switch in the on position.  I do not get 10 ohms.  I
get the same 1000 ohms as listed for AC switch in the off position.  The AC
compressor signal test produced high 4 ohm readings which fall into the 0-5
ohms listed in the table.

My car idles at about 900rpm while in gear and about 1000rpm in neutral.  
This is according to the small tachometer installed in my dash.

I would like to get the car closer to the 775rpm idle speed listed in the
Bently manual.  Should I take care of the AC microswitch and see if that
helps my idle?  Prehaps I should fix it just as standard protocol, so to
speak?

Any suggestions would be appreciated.

Thanks,
Mehmet