AC microswitch tests...

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

 

Testing the micro is pretty easy. Temporarily remove one wire from the
switch, the idle should slow down to 750, if that's what's causing your
problem. However, it sounds like you need to set up the base idle
properly. This job should start with cleaning the throttle body.
There's instructions on www.brickboard.com, in the 700/900 FAQ to take
you through this.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)