I did a search but did not find anything too informative. I cannot seem to figure out the a/c belt. Does it need a special tool to loosen the tensioner? Does anyone know what size wrench is needed to loosen it? The car is an 86 420sel. thanks

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

You shouldn't need a special tool. The tensioner just pivots around a bolt. Loosen either with a 17mm regular wrench or 8mm allen wrench (sizes are from memory, dont quote me!), depending on which your car has. You might need to put (If i remember correctly) a 19mm wrench on the end of the tensioner to rotate it.