I've noticed with a weak tesioner that if I let OFF the accellerator from WOT suddenly, the belt will squeak on DECELERATION and then the A/C will cut out for a while. A new belt and tensioner has fixed it for me consistently. If I use WOT and then let off gently it may not squeak and will usually not kill the A/C.

At 235k miles, I have replaced the tensioner at least twice and probably three times on my 92 400E and similarly on the 92 SL. I may be replacing it too often, but each time it fixes the A/C dropouts after using WOT.

My shop tells me if it ever squeaks it is probably the tensioner and not the belt. Of course, they don't recommend a new tensioner without a new belt to go with it. This shotgun fix seems all too un-scientific, but I cannot argue with success.

I've been reading Arthur's expert detailed posts on this. He seems quite knowledgeable has good information and may have other ideas. If I ever have a complex problem in my electronics I'd appreciate having his input.

Arthur: Any ideas on troubleshooting an intermittent ASR Limp-Home problem on my 92 SL?

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)