Failing AC clutch was bad alternator regulator

[Ionsignal]

Hi all, first post here. I would like to thank all the contributors to the forum, they have been most helpful.

My in-law's S80 developed AC trouble in that after running for 10 minutes the clutch would not reengage. It has 70K, 2.9 auto.

Reading most of the posts for this issue I was lead to believe that the clutch was going bad. But, being an HVAC tech (commercial equipment) my very first system diagnosis is to look at the electrical control of the device.

What I found was that the Battery voltage would start out at 13v+ but would drop over the first 10 minutes to less than 12v--not enough to reengage the clutch. Then I found on other posts that this year Bosch alt. has a known issue with a failing regulator--thank you again to contributors!

After changing the regulator the AC system has worked perfectly (as much as the poor ACC control will let it)

As an added note, a friend with a 2004 Subaru had the exact same symptoms with his AC and the AC shop wants to sell him $800 compressor. We are going to do the alt next week, as it drops voltage as well, and I will post an update on that.

Thanks again for all the help these forums have given us!

[Ionsignal]

Hello all,

Well we did install a new alt. in my friend's Subie and the voltage stays in the 13V range while idling and all the AC stuff running. The clutch now cycles perfectly!

Thanks again for all the great info on this forum.

[jblackburn]

This is something that's never occurred to me, and I'll keep in mind for future reference. I know my alternator is struggling itself, so it stands to reason others may be on their way out as well and causing similar issues. Thanks for sharing