Lately, all of a sudden, I'm getting a blown fuse that protects the automatic climate control, the water pump, and the ambient temperature sensor circuit... The number of the fuse escapes me right now (8? 10?)

I've replaced 2 fuses already over the last couple days.

Today, after another blown fuse, I sensed that one of the relays in the fuse box is HOT. One other was warm, while others were cool.

I have no idea if the blown fuse and a hot relay are related... But what might be causing a blown fuse on this circuit in the first place? My climate control unit is a "new" unit that was rebuilt by Programma, which I installed this summer. It is still under warranty and has been working fine. No other obvious side effects.

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84 300SD - bought in April '06 with 237,000 mi

On the 300D that fuse also controls the kickdown switch for the transmission. When I hit the kickdown switch, the fuse blew.

Got under the car and the kickdown wire leading to the transmission had rubbed through the protective sheathing and was grounding to the chassis.

Secure it with plastic wire ties and some electrical tape, problem solved.

Not sure this is the same for the 126.

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84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)

When you remember the fuse number..........kindly advise.

Check to see if the backup lights work.......or not.........after the fuse blows.

You're right, the kickdown switch is on that same circuit.

So if the wire is bad, the fuse would blow whenever you "floor" the gas pedal?

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84 300SD - bought in April '06 with 237,000 mi

It's fuse #10.

From reading the list of circuit components, I didn't find a kickdown switch on it, but the back-up lights are on it. So are the CCU (climate control unit), temp sensor, water pump, CCU fan, "transmission" (but didnt specify what), and "overload protection".

A curious thing happened last night. I had everything turned on (CCU) and ready to go, so I put her in the reverse, and my temp sensor blanked out. Usually, when the temp sensor goes, I know my CCU will be dead too, a likely indication that the fuse blew. So I'm on the road, driving, and the temp sensor comes back on. My CCU is back on, too!

I get home and park the car. I turn off the CCU but leave the engine running. I run the gearstick through the gears, and the temp sensor blanks out again. I put her back into park. The temp sensor is back on. I run her through the gears again while parked - the temp sensor stays on this time. The back-up lights work the whole time.

Today, I decided not to turn on the CCU for a while. I backed out of my spot and started driving - no problems. Turned on the CCU for a while - no problems. So far, the temp sensor is on, and the fuse is doing fine. I've been trying to avoid having the CCU on the same time I'm backing up.

Maybe it's something to do with the back-up lights switch. I had the dealer replace it this fall because it was dead. They found tranny leaks all around it, so they told me it will probably fail in the near future again, unless I fix the tranny leaks. Do could the tranny leaks be shorting out my backup switch?

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84 300SD - bought in April '06 with 237,000 mi

I had the same thing happening on my daily, I simply wired a circuit breaker into it to replace the fuse.......problem solved.

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

I own an 83 300d.
I have replaced the blower motor and the acc unit and I am still blowing fuses when I turn the fan on high or engage the ac. Last night when I tried it the fuse didn't blow however #8 rapidly became blistering hot . Anybody got any advice or a fix for this problem?

Disconnect the auxiliary fan and drive the vehicle for a few days and see if the problem is eliminated. Try to avoid doing it when the vehicle will be stuck in traffic on 90° days.