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Garage => Mechanicals => Topic started by: cejpat on 07 November 2013, 09:03 AM

Title: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: cejpat on 07 November 2013, 09:03 AM
Mercedes part number: 0008350157

old amplifier unit began smoking, burned out

tried to replace with remanufactured unit. that began smoking as soon as partially plugged in = pulled it off immediately.

what's going wrong?

anyone with a diagram?

i've got a replacement servo (3 years old) from George Murphy at Performance Analysis. He said possibly something broke in his servo = he's happy to test and see what/if anything wrong.

any ideas?
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: Euro_Sled on 01 May 2017, 04:43 PM
did you ever figure out what the problem was with this?  I have a similar issue. 
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: UTn_boy on 02 May 2017, 05:08 PM
9 times out of ten it'll be because the servo has become stuck. 
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: Diesel 617 on 02 May 2017, 06:20 PM
and the remaining 1/10 times the Auxiliary water pump is burned out (its near the servo)

You can disconnect the Aux water pump and put a 9v battery to the connector and if you hear the motor then its good.

I'm starting to really believe that the upgraded aftermarket Climate Control kit is a good investment. Either that or pull a w126 system and fit it.
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: Jed on 24 January 2019, 06:09 PM
Hey Guys,

So if its not a stuck servo (tested with a 9 volt battery and the servo motor runs each way, open and closes)

and it s not a bad auxiliary pump (also tested with power to the leads and runs fine)

but yet one of the resistors on the amplifier keeps burning out as soon as the ignition switch is turned on (glows red hot and burns up)

any idea what else it could be?

1979 6.9, all stock.  system was working perfectly before rebuilt servo started leaking ,was sent back for re- rebuild and reinstalled.

thanks

jed
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: UTn_boy on 24 January 2019, 07:15 PM
The servo doesn't have to be stuck for short out the amplifier.  Unplug the amplifier and see if the resistor stops overloading. 

There could also be a dead short to ground in a power supply wire, and if so, then it'll merely be a matter of tracing the short down.  If you would like a schematic, I'm certain that one of us can supply you with that.  But isn't the schematic somewhere on the forum technical part?
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: Jed on 24 January 2019, 08:22 PM
Thanks
Did you mean unplug the SERVO and see if the resistor overloads? the resistor is on the amplifier board.  I tried that and it does not overload if the 1-5 pin electrical plug on the servo is unplugged.

the rebuilder is telling me that if the motor in the servo works it should not be overloading??? I am skeptical at this point so glad to hear that it can still short.  I will pull a working servo from another car and plug it in and see if that doesn't fix the problem.  first I have to come up with some replacement resistors to solder onto my blown up amplifiers.... ::)

thanks again
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: Malpaso44 on 25 January 2019, 08:57 AM
I live in Georgia and cannot survive without A/C. I replaced my servo a couple of times before I decided to purchase the upgraded unit. I haven't had any problems with the new system.
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: UTn_boy on 26 January 2019, 07:04 PM
Thanks
Did you mean unplug the SERVO and see if the resistor overloads? the resistor is on the amplifier board.  I tried that and it does not overload if the 1-5 pin electrical plug on the servo is unplugged.

the rebuilder is telling me that if the motor in the servo works it should not be overloading??? I am skeptical at this point so glad to hear that it can still short.  I will pull a working servo from another car and plug it in and see if that doesn't fix the problem.  first I have to come up with some replacement resistors to solder onto my blown up amplifiers.... ::)

thanks again

Yes, I meant unplug the servo, not the amplifier.  Sorry about that. 

If the amplifier quits shorting when you unplug the servo 1-5 plug, then it's either the servo or the Auxiliary electric water pump.  I believe you said you already checked the water pump, so that leaves the servo.  Try another servo and see what happens.  Just swap plugs to the test unit without mounting it. 

Regarding your amplifier, do make sure that none of the transistors have fried, as well.  If I remember correctly, the transistors are of the BR series, and are very common, cheap, and easy to find.  If in doubt replace them anyway. 
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: slfan on 03 February 2019, 03:34 PM
I live in Georgia and cannot survive without A/C. I replaced my servo a couple of times before I decided to purchase the upgraded unit. I haven't had any problems with the new system.

Hello,

I am considering upgrading my Climate Control system.  Can you tell me what system you used for this upgrade?

Thank you,
Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: Malpaso44 on 03 February 2019, 07:09 PM
This is the upgraded unit. I don't think you'll regret buying it.

https://www.ebay.com/itm/Mercedes-W116-W123-300D-Upgrade-Kit-For-Climate-Control-Unwiredtools-227550999/112571911101?hash=item1a35cf0bbd:g:Zw4AAOSwLiJZw12B

Title: Re: my heater amplifier burned out ... replacement unit smoking ... short somewhere
Post by: slfan on 05 February 2019, 04:20 PM
This is the upgraded unit. I don't think you'll regret buying it.

https://www.ebay.com/itm/Mercedes-W116-W123-300D-Upgrade-Kit-For-Climate-Control-Unwiredtools-227550999/112571911101?hash=item1a35cf0bbd:g:Zw4AAOSwLiJZw12B

Thank you very much!

Regards,
Angelo