AC Wiring Diagram Needed

Dan Wood

Dan Wood

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I have the Blue Books and looked at all the wiring diagrams I can find. There are some photobucket posts that I can't blow up and read.
I am looking for the wiring diagrams for the AC controls in the console for a 71 2800CS. It would include the thermostat, fan switch, resistor, etc.
Thanks for the help.
 
Here's what I have:

Wiring 1.jpg
Wiring 2.jpg
 
From what I remember you may need to reference all of these while looking at wire colors in your car. There was some inconsistency, maybe because the ac stuff was installed by dealers?
 
And post #20 here has a pretty clear labeled copy

Dead AC

Fairly new compressor. Always works, but today nothing happens as I turn the lower knob. The fuse, 7? Which shares the left door window must be ok, as the window funs normally. Is there another fuse, or relay that I should check? Thanks, Peder
e9coupe.com e9coupe.com
 
Thomas76 said:
From what I remember you may need to reference all of these while looking at wire colors in your car. There was some inconsistency, maybe because the ac stuff was installed by dealers?
Click to expand...
The heat and AC were out when we bought the car. The wiring is there and I need to hook it up. I need to route the wiring and plug it in. Some are easy to figure out but some will need to be traced back.
The wire from the clutch goes into the cabin so I need to find the relay that is in the first schematic.
Thanks for all the help.
 
Last edited:
The relay is a normally closed unit that is right below the fuse box. The black wire opens the relay to deactivate the blower motor
 
As I recall, relay number 9 is attached to the right fender toward the front of the car. Power wire with flying fuse runs across the nose of the car to that relay.

Connector number 6 is under the center console.
 
Thanks to everyone for the help. I have the wiring figured out now and as Chris mentioned in the attached post the AC schematic is in the AC section (64) in the Blue Book. As Don stated the heater motor relay (5) opens when the AC fan is turned on and the compressor clutch wire connects to the thermostat. I believe that relay (9) and motor (13) are for radiator aux cooling.
 
Dan Wood said:
Thanks to everyone for the help. I have the wiring figured out now and as Chris mentioned in the attached post the AC schematic is in the AC section (64) in the Blue Book. As Don stated the heater motor relay (5) opens when the AC fan is turned on and the compressor clutch wire connects to the thermostat. I believe that relay (9) and motor (13) are for radiator aux cooling.
Click to expand...

Yes, relay number 9 engages the fan motor in front of the radiator. Per sfdon's suggestion, I have also added an alternative path to excite relay number 9 using switched power, a temperature switch (88 degrees C, I think) in the bottom of the radiator and a blocking diode. This will engage the fan if coolant temp gets high without the a/c on.
 
9 is the relay to activate 13 the fan in front of the condenser, you need these. The black wire from the temp switch goes to this relay first but not through it and branches to the compressor. In a 74 there is a separate relay to active this fan when the temp sensor at bottom of radiator reaches its limit.
 
Its a great feeling knowing just a little work and a few bucks can save your engine on a hot day stuck in traffic.
 
sfdon said:
Its a great feeling knowing just a little work and a few bucks can save your engine on a hot day stuck in traffic.
Click to expand...
I searched but wasn't able to find the post that discussed the additional thermostat to activte the aux fan. If someone could add the link I would appreciate it. Thanks
 
Is it possible to get a replacement resistor? My AC blows ice cold, but either all on or all off as the resistor is fried.
 
HB Chris said:
9 is the relay to activate 13 the fan in front of the condenser, you need these. The black wire from the temp switch goes to this relay first but not through it and branches to the compressor. In a 74 there is a separate relay to active this fan when the temp sensor at bottom of radiator reaches its limit.
Click to expand...

Hi HB Chris,

Is the fan in front of the condenser suppose to come on when the AC system is first turned on OR does it get turned on at a certain temperature?

Thx

Regards,
Bill
 
It only turns on when A/C temp switch is turned on sending a signal to the relay by the radiator. This same wire branched off from but does not use the relay to turn on the compressor. In 74 another relay and temp sender was added to the radiator to turn this fan on if the car got too hot.
 
HB Chris said:
It only turns on when A/C temp switch is turned on sending a signal to the relay by the radiator. This same wire branched off from but does not use the relay to turn on the compressor. In 74 another relay and temp sender was added to the radiator to turn this fan on if the car got too hot.
Click to expand...

Oh ya...right...the adjustable temp switch on the console has a thermocouple that is connected to the evaporator box.

Thanks for the clarity. Do you know at about what temperature does the console temp switch send a signal to the relay to turn the condenser fan on?

Regards
 
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