Fuse #5 ACC 86SDL - PeachParts Mercedes-Benz Forum

TX76513 · #1 09-17-2004, 01:36 PM

Well #5 fuse (ACC) is giving me the fit's (blowing) - Has anyone run across some "common" problems on troubleshooting this problem

sixto · #2 09-17-2004, 03:57 PM

Usually a sign that the ACC blower is tired but it can last a long time before it needs attention. There's a kit available from MB and FastLane that retrofits 2 fuses in parallel in place of the ACC fuse in the fuse box. It was standard issue in 126s by 91.

Sixto
95 S420
87 300SDL

TX76513 · #3 09-17-2004, 04:16 PM

Thanks Sixto - reading some of the 1000 threads on ACC search - the only other that caught my eye was the kickdown wire that shorts out on the frame that has me suspicious. Gotta have my air

Dervman · #4 09-17-2004, 04:45 PM

Fuse #5 is the Fuse for the A/C Compressor Clutch, but it also feeds the Auxilliary Water Pump. If either one of these is seized or drawing too high amps, then the fuse will blow. If you know the A/C Clutch is OK try disconnecting the Aux. Water Pump and see if that works.

TX76513 · #5 09-17-2004, 05:15 PM

I feel confident about the A/C system - I can replace fuse and all is well for about 15 min. However, will check Auxilliary Water Pump and also need to validate if movement (of vehicle) is playing a roll in this problem. Not that it is HUMID or HOT here

Came back to edit - I don't know if this information has any value - but when the fuse blows it appears the ACC is defaulting to HEAT - which is making for an incredible driving experience. No fans but with the windows rolled down it draws the heat up through the system

sixto · #6 09-17-2004, 08:49 PM

That's normal. The unpowered position of the heat control valve (monovalve) is open. Not so bad when the car is not moving. FWIW, the unpowered position of the ACC vents is defrost.

Sixto
95 S420
87 300SDL

TX76513 · #7 09-19-2004, 02:17 PM

OK disconnected Aux Water Pump and fuse does not blow - fans work normal and strong but the AC does not engage

With that assumption looks like the circuit must be tied together??

psfred · #8 09-19-2004, 02:54 PM

You need a new aux water pump, it's seized.

Peter

Dervman · #9 09-20-2004, 12:25 AM

I had exactly the same problem, but the A/C Compressor Clutch was also bad on mine so even after the Aux. water Pump was disconnected the fuse still blew. A recon. clutch fixed things.

Are you sure you only disconnected the pump or might you have also disconnected the A/C Clutch? Is the clutch getting power with the A/C turned on?

TX76513 · #10 09-20-2004, 09:04 AM

Quote:

Originally Posted by Dervman

Are you sure you only disconnected the pump or might you have also disconnected the A/C Clutch? Is the clutch getting power with the A/C turned on?

Yes, just disconnected the Aux. Pump - did not get into mainstream diagnostics this weekend as I had a few other things on my plate

TX76513 · #11 09-28-2004, 05:13 PM

Cold air again!

The AC Clutch was the culprit -upon examination it was shot

Unfortunately there was oil seeping from the OEM compressor and the shaft rotation didn't sound good. The clutch short also knocked out the ACC pannel. New Compressor and Clutch - since we were there put a new dryer and ex valve on. Were able to R/R the ACC Pannel just blew a soldered connection off (others were loose and coroded). Filtered the R-12 and it's better than ever. Some $$'s but it's worth it on this car