According to the MB service manual, the proper coolant (R134a) level should show some bubbles at start up and then go away (as viewed thru the sight glass) on a normal (70 deg) day. On a *VERY* hot day, you may still see some bubbles.

Overfilling is a great way to make your A/C work poorly!

Here's what I said (assume the a/c is running):
1) bubbles in the sight glass does NOT mean that the a/c is low on 'freon';
2) NO bubbles in the sight glass does not mean that the a/c is correctly filled.

What does that mean? There's only ONE way to be sure that the 'freon' level is correct; you must evacuate the system, and then recharge it to the proper amount specified for that a/c system. Other than that, using the sight glass is only a guess which can be very wrong!

[Edited by JimF on 04-26-2001 at 02:41 AM]

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Regards . . . . JimF
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'94 S500 Cpe

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