I just discovered your post while doing a search for the A/C blower repair.

Hopefully you've already solved your problem.
If you haven't, I will tell you that it could be as simple as your water valve is not working properly and not closing off the hot water from the engine. It's a cheap and simple replacement and install. It's just in front of your battery has a single plug in and two rubber tubes connected to it.

I had this happen to me and so I know the symptoms very well.

Al

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03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather
90 300SEL 214k Pearl Black/ Alto Grey/Black Leather

Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio