What's this contraption? - Page 2 - PeachParts Mercedes-Benz Forum

crhenkel · #16 09-03-2010, 12:29 PM

I was expecting a charging problem too, but it is all replaced and I still have a low charging situation or a heavy draw one or the other.

The alternator is new as is the voltage regulator. The wiring tests ok and the center console volt meter readings match the readings from a multimeter, low voltage.
With headlamps and blower motor on, the voltage dorps to below 9.5 volts.

funola · #17 09-03-2010, 01:19 PM

Well, if you know which circuit is giving you excessive draw, then find out what's causing it and fix it!. I'd start with undoing one fuse at a time and watch the volt meter. The one that raises the voltage is the circuit with the problem. See what other loads are on that circuit.

bigblockchev · #18 09-04-2010, 08:38 PM

If the voltage at the battery terminals is up to spec ie: 13.6 to 14ish and the voltage at the console is only 9.5 then you either have a bad ground or a high resistance connection in a switch or a fuse connection. It just isn't possible to burn up 4-5 volts with high current drain. You would have to be drawing more than the starter cranking to do that, in the neighborhood of 250-300 Amps , which isn't going to happen in those tiny wires. The other possibility is that the blower motor is shot. Too much mechanical drag caused by dry or sticky motor bushings would cause high current consumption, as would partly shorted motor winding. more likely the former than the latter. Try a shot of WD40 on the motor bushings to see if it speeds up and the current goes down. AT high speed the resistor pack is out of the circuit. Does the blower pop the fuse or not? Cheers Dan

crhenkel · #19 09-04-2010, 11:48 PM

Yes, i tend to agree. i have checked out the alternator and the wires and the regulator and it all seems ok. It is just that the accessories are drawing a lot of juice. It seems that the blower is suspect. It could be a ground or I was wondering about the motor going bad. How does one get at the motor bushing to spray them with WD40? Never messed with the blower motor.

I am going to also check the aux fan draw which seems to be a possibility since it comes on with the AC.
The blower motor seems to be working fine, no delay in starting, no noise, it works on all speeds, it doesnt stop or kick out. Does not blow the fuse either. Still could be going bad though.

The biggest draw is at the max fan speed ( makes sense) and you say the blower regulator is only in play at the lower speeds?

I put an amp clamp on the alternator supply wires. With ac on high, lights on and radio and amplifier on it goes up to 59 amps. Then with everything off in park and at idle it reads 16 amps. So it seems that the voltage regulator is doing its job. Still seems as if there is a lot of draw though. As if something is sucking too much juice due to defect or close to failure.

bigblockchev · #20 09-05-2010, 02:00 AM

It is a bit of a pain to get to . It is possible to remove the cover by unsnapping a half dozen or so clips on the blower housing. This is directly under the windshield wiper setup. I suspect that it is possible to get a spray nozzle in there without removing the wiper assembly but if you need to get the motor out then it's gotta come out. There are a couple of good tutorials on removal on the forums if you search. Cheers Dan

crhenkel · #21 09-05-2010, 02:16 PM

I appreciate the info on how to access the blower motor. I am going to try to access the motor and spray it down a bit just in case the bearings are gummed up a bit, as far as I know it is the original motor and it has about 100,000 mle on the car.
It would be great if the motor is just dealing with some extra resistance and the lubrication frees it up! I was wondering about that myself but was dreading having to get at the motor. Doesnt sound too bad to at least try to lubricate it a little. Might work.
Thanks