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0to60in6min
Samba Member
Joined: November 27, 2006
Posts: 3417
Location: OR & CA (Oregon/California)
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 Posted: Fri Sep 26, 2014 12:18 pm Post subject: A/C wiring... please help... |
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hi all,
the A/C shop opened the driver side rear panel to service the A/C on my 1990 Carat then I discover this weird wiring done by the previous owner
the Green/Black wire was cut and connected to the Blue wire
could you please tell..
- what the black box (with the white dot) where the wires are coming from is for
- what is the functionality to re-wire as original or leave it as is...
note: I just finish putting this Carat back not long ago, so it's still new to me...after the A/C was serviced it's cold now, but the idle is quite erratic with the A/C on - sitting at 2000rpm some time...
many thanks |
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crazyvwvanman
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Joined: January 28, 2008
Posts: 9937
Location: Orbiting San Diego
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| Posted: Fri Sep 26, 2014 12:38 pm Post subject: |
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Someone hot wired it to always run the compressor no matter what temp setting is on the front control knob. Normally when the A/C is on the ceiling fans blow air all the time but the compressor only cycles on and off as needed to keep a certain temperature. The way your wires are now it will never cycle off no matter how cold it is. ha ha
The black box is the thermostat temp sensor for the rear unit fins. The front temp setting knob tells the black box how cold you want the inside air. Then the black box compares what you want to how cold the fins are and controls the compressor to keep cooling until the sensor reading matches the knob setting.
It is possible the the black box went bad or the front temp setting rheostat went bad. Now the hotwire fix means those 2 parts don't do anything now.
Mark |
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0to60in6min
Samba Member
Joined: November 27, 2006
Posts: 3417
Location: OR & CA (Oregon/California)
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| Posted: Fri Sep 26, 2014 1:24 pm Post subject: |
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thanks Mark,
great info...
I will re-wire as original and will se how it works...
btw... what's the name of the black box?, in case in have to replace it?
thanks |
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1vw4x4
Banned
Joined: June 22, 2005
Posts: 472
Location: Pgh. PA
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| Posted: Fri Sep 26, 2014 7:57 pm Post subject: |
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What he said...... but the compressor may still cycle if they left the
high pressure switch intact.
Those black boxes are made in japan. They fail mainly because
the van has lost the battery ground at some point. When this happens
the alternator has no load and the voltage can spike. These boxes
are sensitive to the spike and burn up. I've fixed a few of these, but really not worth the time.
| crazyvwvanman wrote: |
Someone hot wired it to always run the compressor no matter what temp setting is on the front control knob. Normally when the A/C is on the ceiling fans blow air all the time but the compressor only cycles on and off as needed to keep a certain temperature. The way your wires are now it will never cycle off no matter how cold it is. ha ha
The black box is the thermostat temp sensor for the rear unit fins. The front temp setting knob tells the black box how cold you want the inside air. Then the black box compares what you want to how cold the fins are and controls the compressor to keep cooling until the sensor reading matches the knob setting.
It is possible the the black box went bad or the front temp setting rheostat went bad. Now the hotwire fix means those 2 parts don't do anything now.
Mark |
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0to60in6min
Samba Member
Joined: November 27, 2006
Posts: 3417
Location: OR & CA (Oregon/California)
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| Posted: Sat Sep 27, 2014 10:48 am Post subject: |
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1vw4x4 ...
that black box has a name.. what's called?
thanks |
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kamzcab86
Samba Moderator
Joined: July 26, 2008
Posts: 7925
Location: Arizona
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| Posted: Sat Sep 27, 2014 11:11 am Post subject: |
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| 0to60in6min wrote: |
| that black box has a name.. what's called? |
Thermostat, part #253965581.
_________________
~Kamz 
1986 Cabriolet: www.Cabby-Info.com
 1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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1vw4x4
Banned
Joined: June 22, 2005
Posts: 472
Location: Pgh. PA
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| Posted: Sat Sep 27, 2014 6:23 pm Post subject: |
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What he said ...again.... but I don't like to call it that,
because of the way it operates. To me thermostats are typically
mechanical devices, but that's just me, getting old.
| kamzcab86 wrote: |
| 0to60in6min wrote: |
| that black box has a name.. what's called? |
Thermostat, part #253965581. |
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Bassyaks
Samba Member
Joined: October 06, 2010
Posts: 1137
Location: S.E. Connetitcut
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| Posted: Sun Jul 30, 2017 6:57 am Post subject: Re: A/C wiring... please help... |
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Getting into new territories here, if the thermostat (part #253965581) is jumped is there possibility of line pressures building up too excessive if the compressor is not manually cycled? Or do the fans control the pressure by cooling do the refrigerant .
The question is can I safely run the A/C by cycling the compressor manually?
Thanks |
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
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Bassyaks
Samba Member
Joined: October 06, 2010
Posts: 1137
Location: S.E. Connetitcut
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| Posted: Sun Jul 30, 2017 7:08 am Post subject: Re: A/C wiring... please help... |
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| Sorry, 86 westy, wiring in the cabinet. Do you have any info on which switch you used, did you use a port on the RD to install it? |
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
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dgbeatty
Samba Member
Joined: October 26, 2006
Posts: 702
Location: Sacramento
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| Posted: Sun Jul 30, 2017 12:10 pm Post subject: Re: A/C wiring... please help... |
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| Please refer us to the Bentley page(s) you have questions about. |
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Bassyaks
Samba Member
Joined: October 06, 2010
Posts: 1137
Location: S.E. Connetitcut
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| Posted: Sun Jul 30, 2017 12:33 pm Post subject: Re: A/C wiring... please help... |
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Bentley is pretty-well useless when it comes to A/C, there are too many variations.
Dave I found and order it Thanks, Classic TK in that topic, made me laugh. |
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