Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-29-2011, 01:06 PM
Registered User
 
Join Date: Jul 2007
Location: Bainbridge Island, WA
Posts: 66
Wiring the heater blower independently

Hi all,
I've decided to run independent wiring to my new heater blower and connect it to an independent variable speed fan switch. Long story short, I'm happy to have only defrost and have torn out the climate system.

My question is, where is the best place to connect my positive wire? I'd rather not have to run it all the way to the solenoid or battery, and will have an inline fuse, but don't know if there is another positive terminal within the car that would avoid me having to run wire into the engine compartment.

I'm going independent because I have a blowing fuse problem with the existing wiring and can't seem to find any simple fixes within the maze of now defunct climate system wiring.

Any help is appreciated as the car has been garaged for a month now and I am eager to get her going again. Other than the damn climate system, she is in absolutely excellent shape!

__________________
Where there's a will there's a way
1978 300D
Reply With Quote
  #2  
Old 12-29-2011, 01:38 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,856
no.
you will need to at a minimum run to the fuse box. nothing else in the dashboard has the amp capability to handle the blower draw...

the simplest thing to do would be to run to the fusebox inside the chase designed for all the wires, and tie into the fuse bar there.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #3  
Old 12-29-2011, 02:25 PM
Registered User
 
Join Date: Jul 2007
Location: Bainbridge Island, WA
Posts: 66
Thanks vstech.

My concern running to the fuse box has been that I want to avoid whatever short exists in the system currently that is causing all the blown fuses. And by the way, I did try out upgraded ceramic and glass fuses and they all blow, even with the brand new blower.

If the fuse box is fed by a single large gauge wire, as it would be on a sailboat (which is my area of better DC system mastery), then I can see that it would be fine to feed off of it and run the ground to a different spot, thereby bypassing the existing wiring.
__________________
Where there's a will there's a way
1978 300D
Reply With Quote
  #4  
Old 12-29-2011, 02:53 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,856
it is fed with a large #6 or 4 wire, so yeah that would work, but the header for the box is common to that large wire, so any fuse position should work to feed your blower. BE SURE TO USE A FUSE!
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #5  
Old 12-29-2011, 03:33 PM
Registered User
 
Join Date: Jul 2007
Location: Bainbridge Island, WA
Posts: 66
Excellent vstech.
Peachparts crashed and I don't have time to retype my longer reply, but thanks.

This should be straightforward, other than running the wiring through the firewall. I will indeed fuse the new line! The blower draws somewhere around 10 amps max, and the standard MB fuse of 16 amps should be sufficient to protect the wiring. I'll use 14 gauge which is rated to 25+ amps.
__________________
Where there's a will there's a way
1978 300D
Reply With Quote
  #6  
Old 12-29-2011, 07:25 PM
compress ignite's Avatar
Drone aspiring to Serfdom
 
Join Date: Feb 2004
Location: 32(degrees) North by 81(degrees) West
Posts: 5,554
Unsolicited Caution

If You'll follow me for a minute...
1.You've Disabled/Disconnected/Cut the Wires between your former CCU and the
Blower,Fuse Box,Battery.
2.You've admitted to a possible Dead Short existing in the Wiring "Somewhere"
between the Laurel Leafed Star and the Rear Bumper,Bad enough that it blows fuses.
3.You've LEFT the Questionable Wiring INTACT (Still in the Chassis)?
4.Most Important...You've NO Idea WHAT'S shorting out WHERE to WHAT.
5.Sure sounds like an Electrical Fire Opportunity to me.

[Is there just one "Short" ? or a series? Is the cause insulation degradation?]

(Just another added benefit...You've posted such on an Internet Forum.
Think about the Insurance [Or it's Denial of Coverage] "Difficulties")
__________________
'84 300SD sold
124.128
Reply With Quote
  #7  
Old 12-29-2011, 07:52 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 51,835
Both My Mercedes and My Van have a Blower Resistor in them.

I do not know how it functions with the knob thar varies the Fan Speed but will he need to have one in His Circuit when he rewires?
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #8  
Old 12-29-2011, 08:22 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,856
Quote:
Originally Posted by compress ignite View Post
If You'll follow me for a minute...
1.You've Disabled/Disconnected/Cut the Wires between your former CCU and the
Blower,Fuse Box,Battery.
2.You've admitted to a possible Dead Short existing in the Wiring "Somewhere"
between the Laurel Leafed Star and the Rear Bumper,Bad enough that it blows fuses.
3.You've LEFT the Questionable Wiring INTACT (Still in the Chassis)?
4.Most Important...You've NO Idea WHAT'S shorting out WHERE to WHAT.
5.Sure sounds like an Electrical Fire Opportunity to me.

[Is there just one "Short" ? or a series? Is the cause insulation degradation?]

(Just another added benefit...You've posted such on an Internet Forum.
Think about the Insurance [Or it's Denial of Coverage] "Difficulties")
he said he had a short that was blowing a fuse. and he's wiring directly to avoid the shorted wire, leaving that wire without a fuse, or power at all. I think that's safe, no?
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #9  
Old 12-29-2011, 08:23 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,856
Quote:
Originally Posted by Diesel911 View Post
Both My Mercedes and My Van have a Blower Resistor in them.

I do not know how it functions with the knob thar varies the Fan Speed but will he need to have one in His Circuit when he rewires?
he stated he's installing a blower control device to the direct wiring he is installing. it must have it's own resistors to lower the speeds on the blower.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #10  
Old 12-29-2011, 09:54 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 51,835
Quote:
Originally Posted by vstech View Post
he stated he's installing a blower control device to the direct wiring he is installing. it must have it's own resistors to lower the speeds on the blower.
I hope He comments on that.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #11  
Old 12-30-2011, 03:31 PM
compress ignite's Avatar
Drone aspiring to Serfdom
 
Join Date: Feb 2004
Location: 32(degrees) North by 81(degrees) West
Posts: 5,554
Obsessively safety oriented

VS,

If "Zomezing" is blowing fuses I wanna know what it's cause.
(AND "Fix" it!)

Especially given this manufacturers propensity for "Minimum" Wiring specs.
AND all the equipment's Age!

What may have been perfectly acceptable in Sindelfingen 20-30+ years ago
CAN bring an Involuntary "Car-B-Que",Today.

Rats,Martens,Etc. add to the unseen dangers.
__________________
'84 300SD sold
124.128
Reply With Quote
  #12  
Old 12-30-2011, 07:37 PM
Registered User
 
Join Date: Apr 2011
Location: SF, CA, USA
Posts: 935
> it must have it's own resistors to lower the speeds on the blower.

a modern alternative to resistors - not available in the '70s - is to a pulse width modulation circuit.

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 07:53 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page