Re: Should I replace A/C fan switch on 85 Mercedes 300SD?

Jul 17, 2003 4 Replies

Just go to any old MB dealer and buy the switch. Why is this a hard to find item?


I am getting ready to do a R134 conversion on this car, it lost the R-12
> charge. I went and bought an new receiver/dryer (no, it it not an
> accumulator) for it, and discovered that the electric fan pressure switch,
> which is mounted in the receiver/dryer, had been disconnected before I
> bought the car. A mechanic had inserted a jumper wire into the two leads
> that were connected to the switch to make the fan run...constantly now,
> whenever the A/C is turned, on I presume. This must have been done because
> the switch went bad, and they didn't want to have to do a recharge just to
> get a non-essential switch replaced.
> So now I am having trouble locating this pressure switch. Wonder if this
> is really necessary? Maybe I could just not replace it....just transfer it
> over to the new receiver/dryer and leave the fan control circuit bypassed?
> Any downside to this, other than wearing the fan out quicker?
>
>

Part number for the switch is 004 820 68 10. List price is $32.50. You can probably get it at less then list from one of the online parts suppliers.

I would replace it. There is no downside other then the shortened fan life, but switches are cheaper then fans.

HTH, Dave

If you are doing a conversion, BE CAREFUL which fan pressure switch you get. The original is calibrated for R-12 pressures and the one you will want is for R-134 pressures - their chemical properties are not the same so you'll also need a new low pressure compressor cut-out switch when there's not enough R-134 in the system.

the more air over the condenser coils the better. better cooling that is.

i my self would leave the fan running when the compressor is on.

but that is me.

the case, minus a few cans!

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