Rear Window Defroster Problems - 240D

The past couple of mornings, I have had to make use of my defroster to clear the windows (55F or less next to the KY River). The front and side windows are clearing fine, but the rear window defroster is not working well.

I activate the switch, the indicator light is coming on, and after about 15 min the window will start to clear because of the air flow.

I have checked the continuity (sp) of the defrost grid and the wiring seems fine. It was working last spring, but was getting slower to react.

Is there a fuse I am missing or maybe some junction point that is corroded over thus increasing the resistance in the circuit? I am missing something, any help in this would be appreciated.... I do not have a schematic of the defroster circuit in my book.

Thanks in advance,

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William
76 240D (W115) - 550K miles
78 300D (W123) - 200K+ miles

[This message has been edited by WmHarlow (edited 08-23-2000).]

Still need some info.... have looked everywhere.
Thanks,