AC compressor circuit - BMW Forum -

3-Series (E21, E30) Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.

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post #1 of 2 (permalink) Old 04-16-2004, 08:22 AM Thread Starter
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The AC compressor clutch in my 1984 318i does not engage when the AC is turned on. All other related circuits (idle up, blower) operate correctly. Neither my owners manual or the Haynes manual identify any circuit protection other than a fuse in the panel, which is okay.

Is there an in-line fuse to the AC clutch or is it protected by a relay, and if so, which relay is it? (The relays are not identified by circuit in either the OM or Haynes.

TIA for any and all help.

Mike Bishop
Santa Rosa, California
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post #2 of 2 (permalink) Old 04-17-2004, 04:35 PM
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KC Ron Carter is an unknown quantity at this point
There are switches in the two bottom vent selectors. One must be open or the A/C compressor will not get voltage.

On the dryer there is a low pressure and a high pressure switch to prevent system damage if service is off.

Those are the hidden issues used to control the A/C besides the snow flake switch.

On some compressors there is a thermal overload switch but I have never seen one bad.


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