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Old 04-25-2001, 12:58 PM
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JimF JimF is offline
'94 S500: only 793 sold!
Join Date: Mar 2001
Location: San Diego, CA
Posts: 1,925
a/c coolant level

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]
Regards . . . . JimF
'94 S500 Cpe

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