I'm getting DTCs 5 and 6 on my base module (socket 8 of the 38 pin connector).

DTC 5 says that the maximum allowable temperature in the module box has been exceeded (F23).

I think my year model had a cooling fan on the box. I'll check out the fan to see if it's still working, although, I understand that later years had the fan deactivated anyway.

Code 6 indicates the a/c electronic clutch is jammed or the poly v-belt is broken. The a/c works fine and the poly v-belt has not broken. Any ideas on this one?

Could the two codes be related to one problem?

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

Not much to worry about - just clear the codes and see if they come back. At some point in the past the AC clutch was blocked - normally because the AC compressor RPMs did not match the engine RPM, either because of a belt slip problem, or because a RPM signal was missing. You may have a budding problem somewhere but no reason to worry about now if the AC is working.

See if bottom engine cowling shroud has not been put back on.
They should always be re-installed, even if you have to go get new fasteners......

Thanks to both of you. I guess that's good news. I cleared the codes and I'll let you know if they come back. The bottom cover is installed, but we've been getting heavy rain and I'm wondering if some water got into the a/c clutch as the car was driven through standing water. It's tough to know what conditions it was exposed to when there's more than one driver.

As for the module box overheat, do you know if MB discontinued the fan exhaust on later models because it wasn't necessary, or was there additional venting on later models?

__________________
1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles