Make me an offer on a great condition, recently rebuild Climate Control Unit that was among a few newer, known good parts we removed for resale from our 1986 300E before we retired it to the California Smog Buy Back program. We bought it 10/30/05 for $335.72 from FastLane. It is a "Programa" rebuilt unit, and at the time of purchase our old non-working core was valued at $200. The part number is #124 830 0885.

This is the unit to buy if your older 124 model heater is acting up, or even just as a spare, since these climate control units are finicky bits in the older MB's. A few tips from experience:

1. The older 124 climate control system adjusts the heat with timed pulses of electricity to a $150 monovalve plumbed into a hose on the passenger side of the engine compartment, near the battery, a little silver cylinder sticking up with two prong plug by it. The pulses of electricity hold the valve shut, not open, so no electricity = full heat. A quick check whether your heat trouble is "control related" is to unplug the connector to the monovalve and see if you get full heat.

2. MB considered good "windscreen defrost" a safety issue, so the defrost button will often work when nothing else will. If your heat works OK in defrost mode, but nothing else, it suggests a control unit issue.

3. There is a tiny pump, on the fender well under the coolant tank on older cars, up near the battery on newer ones, that helps make more heat (through more circulation) at idle when the revs are low. These "auxiliary water pumps" or "circulating pumps" are known to corrode over time and need more power to turn, eventually pulling so much power they burn out the board in the climate control unit trying to drive them. If you've been through a few of these pricey climate control units, change the $70 "auxiliary water pump" when you put the new unit in, or just leave the pump unplugged

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