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 02-26-2010, 03:42 PM
Registered User
 
Join Date: Sep 2006
Posts: 298
ACC Question 1983 300SD

The fan switch as we know has three buttons, high, low and auto.

When I press the Auto button it does not hold, as in it doesn't click in like the high and low fan buttons will. It will cancel either low or high, whichever function was being used, but not click in.

Questions:

What is the proper effect of the auto button?
Is it supposed to click into place?

__________________
This area is typically used to brag about one's current or former automobiles.
Reply With Quote
  #2  
Old 02-26-2010, 03:46 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
The proper effect is to control the fan speed based on air temp at the sensor and temp selected at the wheel.

The Auto button on my car does not "click" either.
__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
Reply With Quote
  #3  
Old 02-26-2010, 03:49 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
My 1981 wagon only considered those buttons as ' Mild Suggestions from the driver' and felt free to ignore or wait 20 minutes to respond....
I suspect the canceling of the low and high is proper...
what it relies on to act I am not sure off hand.
Try turning the temperature regulator farther one direction or the other and give it some time to see if it does in fact come on in response to that nudging...
Reply With Quote
  #4  
Old 02-26-2010, 03:52 PM
Graplr's Avatar
Registered User
 
Join Date: Apr 2007
Location: Huntington Beach, CA
Posts: 1,649
This is normal operation for this button. AUTO means exactly that. The ACC will automatically control the car's temperature based upon the wheel setting and ambient air temperature. It takes awhile for the AUTO setting to kick in (meaning NO button is depressed on the PBU) and the fan to start but it does. The heating and cooling are iffy at best in my car so I almost always have FULL heat, FULL air, or OFF depending upon the season.
__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD


Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD
Reply With Quote
  #5  
Old 02-26-2010, 03:57 PM
Registered User
 
Join Date: Sep 2006
Posts: 298
Quote:
Originally Posted by Graplr View Post
This is normal operation for this button. AUTO means exactly that. The ACC will automatically control the car's temperature based upon the wheel setting and ambient air temperature. It takes awhile for the AUTO setting to kick in (meaning NO button is depressed on the PBU) and the fan to start but it does. The heating and cooling are iffy at best in my car so I almost always have FULL heat, FULL air, or OFF depending upon the season.
I shouldn't be too greedy here as I have great heat and ac and proper vent functionality.

I haven't used the auto feature, mainly because I assumed the auto button was supposed to remain depressed and assumed because it was not that the system was not functional.

Great news. Thanks!
__________________
This area is typically used to brag about one's current or former automobiles.
Reply With Quote
  #6  
Old 02-26-2010, 04:00 PM
Skid Row Joe's Avatar
Banned
 
Join Date: Oct 2007
Location: #KeepingAmericaGreat!
Posts: 7,071
Quote:
Originally Posted by tr1cky View Post
Questions:

What is the proper effect of the auto button?The AUTO button, cancels LOW and HIGH. It has no "in," clicking position.
Is it supposed to click into place?No.
Sounds like you need a new "brain" selector bar. I bought one for my SD when it acted-up as you are describing. It was about $115.00, new from MB dealer 13 years ago or so.
Reply With Quote
  #7  
Old 02-26-2010, 04:01 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
I really do not trust the auto system..
is there something pulling ambient air from the passenger area across some sensor in order to start it up ?
Reply With Quote
  #8  
Old 02-26-2010, 04:06 PM
Registered User
 
Join Date: Sep 2006
Posts: 298
Quote:
Originally Posted by Skid Row Joe View Post
Sounds like you need a new "brain" selector bar. I bought one for my SD when it acted-up as you are describing. It was about $115.00, new from MB dealer 13 years ago or so.
I'm confused. If your answer describes that my unit is functioning properly then why would I need a new "brain" selector bar.
__________________
This area is typically used to brag about one's current or former automobiles.
Reply With Quote
  #9  
Old 02-26-2010, 04:07 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
Quote:
Originally Posted by leathermang View Post
I really do not trust the auto system..
is there something pulling ambient air from the passenger area across some sensor in order to start it up ?
On the w123, that little vent in the center of the dash (The famous rotted foam tube is connected to) air is pulled across the air temp sensor by the cabin fan. IIRC, air is pulled by the w126, but it's intake is close to the rear view mirror.
__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
Reply With Quote
  #10  
Old 02-26-2010, 04:09 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
Does the cabin fan run all the time ? Or all the time the car is running ?
Reply With Quote
  #11  
Old 02-26-2010, 04:11 PM
Skid Row Joe's Avatar
Banned
 
Join Date: Oct 2007
Location: #KeepingAmericaGreat!
Posts: 7,071
Quote:
Originally Posted by tr1cky View Post
I'm confused. If your answer describes that my unit is functioning properly then why would I need a new "brain" selector bar.
Scratch getting a new one then.
Reply With Quote
  #12  
Old 02-26-2010, 04:23 PM
Registered User
 
Join Date: Sep 2006
Posts: 298
Quote:
Originally Posted by Skid Row Joe View Post
Scratch getting a new one then.
Thanks, I am just making sure that I'm reading it right. Its been a long week and my brain may be a bit mushy.

Thanks for your input.
__________________
This area is typically used to brag about one's current or former automobiles.
Reply With Quote
  #13  
Old 02-26-2010, 04:24 PM
Registered User
 
Join Date: Sep 2006
Posts: 298
Quote:
Originally Posted by leathermang View Post
Does the cabin fan run all the time ? Or all the time the car is running ?
I will have to check. Unless i hit the O button, i believe i always have air of some type.
__________________
This area is typically used to brag about one's current or former automobiles.
Reply With Quote
  #14  
Old 02-26-2010, 04:27 PM
rrgrassi's Avatar
mmmmmm Diesel...
 
Join Date: Jun 2006
Location: Royse City Tx
Posts: 5,177
Quote:
Originally Posted by leathermang View Post
Does the cabin fan run all the time ? Or all the time the car is running ?
The fan runs when the any button except the off button is pressed. Auto mode is enabled when the center button or the button between the center and off are pressed in.
__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
Reply With Quote
  #15  
Old 02-26-2010, 04:49 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
Well, with that information I now trust that ' auto' button... Thanks..

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 09:55 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