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Old 10-13-2003, 01:59 PM
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Join Date: Oct 2002
Posts: 75
Replacing aux. pump and climate control unit...more?

I have searched the archives and think I have a handle on the problem...MN winter coming and heat is not working properly in my "new" 1987 190 2.5 turbo.

When I took the vehicle for a test drive last summer the AC seemed to work fine as did the heat. After I bought it the AC compressor clutch would no longer switch on and the heat never really seemed to turn off completely. The car had been "stored" for a long time prior to sale...possibly several years.

After checking the fuses I removed the aux. pump and found it not working. Disassembly showed it was not rebuildable as the rotor was too worn down to turn down. It was seized solid.

Since my climate control pushbuttons did also seem to not function correctly I removed the pushbutton unit and "opened it up" finding the silvery ribbons on the board very wrinkled looking as if they had been overtaxed/overheated. I assume that they are normally flat and unwrinkled. Yes?

I recall that I tested the heat AFTER I tested the AC when I test drove the vehicle. I suspect that when I switched the climate control to HEAT from AC the seized pump fried the pushbutton control module. This would explain why every thing appeared to work during the test drive....and not after. This made sense after reading the previous strings on climate control,heating,and aux. pumps.

I plan on replacing the aux. pump and climate control unit...and wiring in a 1amp slow blow fuse as suggested in earlier posts. I also plan on replacing the heater valve since I believe it must be the reason the heat never seemed to shut off correctly...and it is only $17.25..which seems like a small price to pay compared to the $400 the other two bits will cost. I also plan on flushing my heater core.

I would really appreciate any comments or feedback on my "diagnosis" as well as the wisdom of replacing the heater valve. Are there any other components I should test while I am at it? This forum has been a great source of information so far and before I order parts and tear into the repairs I thought it prudent to ask.


Dana Linscott
Vegoil converted truck...vegoil converted 1987 190DT, 300 series next.
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Old 10-13-2003, 02:17 PM
Rick Miley's Avatar
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Join Date: Jun 1999
Location: Land O Lakes, FL
Posts: 3,086
Sounds like you're right on.

Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
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