First, how about using the default font? That eye chart is difficult to read. In fact for the benefit of others, here's your post is a more legible form -
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Originally Posted by JOE49
Fuse "D" melted plastic on fusebox. '88 300ce. 1st. Benz for me (112,505 miles). All fuses are new, copper (Flosser), OVP is new too (per forum advise), AC was converted to R134a at 85,000 miles by orig. owner at Beck Benz of N. Carolina. Was evacuated & re-charged at 112,982 miles due to AC blowing cold when first turned on, but after parking & re-starting no more cold. Now has 113,072 miles & fall is here, so tried heat & no hot. Looked under fuse cover yesterday & found melted plastic at fuse "D" . Removed screws of cover to inspect beneath & ran out of daylight. Am going over wiring diagrams found at Benzworld. What could have caused this ?? Where to start ???
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Fuse D is for the aux fan. I think there's only one fan in an '88 CE. I don't know why it didn't blow in a peaceful manner. It looks intact in your pictures.
While the aux fan usually comes on to cool the condenser, the aux fan circuit is isolated from the ACC ciruit. The only common wiring is a shared ground for the refrigerant low pressure switch and aux fan. Logic suggests you can't short circuit a ground wire in a manner that will overload the circuit but I'll defer to an expert.
The first thing I'd check is the aux fan. Does it spin freely by hand? Is there axial or radial play in the motor? Disconnect the fan from the harness and momentarily hook it directly to the battery. It will spin backwards if you get the polarity wrong but it won't harm the fan or battery for this diagnosis. Increased electrical load from a stuck or binding fan overloads the circuit and should blow the fuse. But if the fan passes the basic tests, the fault likely lies elsewhere. Maybe relay B (K9 = high speed) or C (K10 = low speed) is bad. Or there's a short in the power wires to the fan.
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Was evacuated & re-charged at 112,982 miles due to AC blowing cold when first turned on, but after parking & re-starting no more cold.
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Sounds like a Klima relay issue, not a charge issue.
Might the aux fan have been modified to run continuously when the compressor is engaged? Otherwise reasonable techs have done sillier things.
Sixto
87 300D