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

Reply to
lucidlamp
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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

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in the 700/900 FAQ to take you through this.

Reply to
Mike F

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