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  #1  
Old 08-28-2004, 08:43 PM
cmichalik
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Question A/C Electrical Problem

I'm sure hoping to get some help here. I've been fighting small problems that have all manifested themselves into big problems. Vaccum & an a/c fan blower motor that is flaky at best. I've fixed the vaccum. The main problem now is the fan blower motor. I had it out to repair a spade connection that broke. When i put it back in I decided to hook it up for testing first (before i put everything back together & have it not work. It came on alright, but when i picked it up it got faster. It ran When I held it upside down it would blow very fast (like it did when I bought the car), and when I held it right-side-up it slowed way down & eventually stopped. I pushed a few a/c control buttons to see if I could coax it into coming back on. It did when I turned it upside down again. Next thing, it stopped and the control unit (where the buttons are) started clicking/popping & the whole system died.

Went and got a new (used) fan and control unit from a bone yard. We tested them at the yard & they both work fine. Put them in the car, nothing. Checked the fuses. Ahh. Blown a/c fuse. Not only blown, but it got so hot that the fuse block melted at the back of the fuse where the holder is mounted to the "plastic" fuse block. Got that all fixed up & put in a new fuse. started over testing to see if the "new" parts work. Still nothing. Got an ohm meter & tested the fuse connection. I think I'm on the right track now. there is no power at the fuse when the car is running & the a/c is turned on (but still not running). All the other fuses had power. Any ideas on why the a/c fuse isn't getting power? Is there anything between the fuse and the battery that could have fried when the system died? What do I check now? I'm at my wits end & I'm ready to get ride of it!!!!

Help!! Signed no a/c in Texas.

Thanks ahead for any direction ya'll can give me.
Cmichalik

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  #2  
Old 10-05-2004, 08:58 PM
whunter's Avatar
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Hello wits end

Have any luck or still the same?
Need update, before offering advice.
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  #3  
Old 10-06-2004, 08:27 AM
cmichalik
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I guess it is time for an update. The electrical portion of the A/C system is working now. In my original post I mentioned that the fuse had gotten so hot that it melted the fuse block. A better description: one side of the fuse holder is spring loaded & the other end is fixed in place. Well as the fuse started to heat up the spring loaded end pushed the hot fuse into the melting plastic. I still don't know why this happend. Since a portion of the block is melted I took out the fuse block & removed the A/C circuit from it. I put an in-line fuse under the dash above the brake pedal and hooked the A/C system to it. All seems to be in working order, but I would still like to know why the fuse gets so hot. Maybe it's been getting hot all along. Who knows.

Thanks for asking. I'll still take some suggestions if anyone has any.

Cmichalik
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Old 10-06-2004, 09:59 AM
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Some thoughts.

These are guesses only, need further data = AMP draw.

The blower motor bushings may need lubrication.
The blower motor brushes may be bad.
The Compressor clutch may be going bad.
A wire shorting or cross circuited and back feeding something.
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Old 10-06-2004, 10:43 AM
cmichalik
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How do I lubricate the motor bushings?

I was originally thinking a short in the fan motor. The fan motor has since been replaced w/ one from a junk-yard. I looked at the bruhes and they were better than the ones I had in my old one. The replacement motor had brushes that were at about 50%. My old motor had brushes that had gotten down to about 80% wear and I rebuilt them 2 years ago.

A few weeks ago I was at a friends house charging the freon and he mentioned to me that the compressor isn't all that it could be. He said it looked like it may be on the way out in the near future, but it doesn't need replaced right away. I still have a little more time on it.

As far as a short in the system somewhere, if this ever happens again I'm going to take it to an automotive electrical shop that my familly has used off & on for the last 20 years.

Thanks for the input
Cmichalik
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Old 10-06-2004, 08:06 PM
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Thumbs up Hypo from drug store + sewing machine oil.

Hello cmichalik

Have you checked the heater blower motor???
They both need to be lubricated...

1982 Mercedes Benz 300TD Turbo Wagon
Part: A/C Blower Motor

Heater Motor w/out Fan Bosch IN STOCK $152.30

A/C Blower Motor with Fan Behr IN STOCK $410.08

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CJ15F2MJ&year=1982&make=MB&model=300-TDT-001&category=R&part=A%2FC+Blower+Motor
Attached Thumbnails
A/C Electrical Problem-oil_a_c-blower-motor-fan.jpg   A/C Electrical Problem-oil_heater-motor-w_out-fan.jpg  

Last edited by whunter; 10-06-2004 at 09:07 PM.
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  #7  
Old 10-07-2004, 08:12 AM
cmichalik
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Ummm..... Aren't the heater blower motor and the A/C blower motor the same motor. I've had my entire dash torn down before & there is only one motor that I have found. It's under the glove box. Please update me on where the second motor could be.

I have always noticed that the catalogues list a heater & the A/C w/ seperate motors. I've also noticed that one motor is always more expensive and it comes w/ the cover & the round fan blades. The cheaper one is always just the motor.
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Old 10-07-2004, 09:25 AM
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No

The heater blower motor and the A/C blower motor are not the same motor.
Ask psfred, Larry Bible or one of the other members.
Can't recall where the heater blower motor is located.

Last edited by whunter; 10-07-2004 at 09:37 AM.
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  #9  
Old 10-07-2004, 09:30 AM
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Quite the contrary, the a/c motor and heater motor are one and the same. Part # 123 820 16 42. All one has to do is check the Mercedes EPC to verify this. Good luck with your doctors appointment.
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  #10  
Old 10-07-2004, 09:33 AM
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I had a simmilar problem.... I bypassed the fuse block and added a 30Amp fuse. Then I traced an Amp draw issue with the condenser fan, I unplugged the condenser fan and the fuse stopped blowing, I haven't got around to replacing the condenser fan yet....
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  #11  
Old 10-07-2004, 10:00 AM
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Red face Hi Rusty

Quote:
Originally Posted by Rusty Cullens
Quite the contrary, the a/c motor and heater motor are one and the same. Part # 123 820 16 42. All one has to do is check the Mercedes EPC to verify this. Good luck with your doctors appointment.
E gad, once again I prove how human I am.

Thank you Rusty.

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