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Fan switch wiring for 240z with a/c


jgramignano8

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I have taken the dashboard out of my 71 240z and when putting everything back in i have run into wire troubles.  Have not been able to find out where the RED, BLACK, and GREEN wire go that come from the wire harness that connects to the fan switch.  The green wire is attached to the switch itself, but the red and green come from the harness.  The z also has a/c and i do not know where the blue wire that is taped around the harness goes either. i have taken a picture.  Help!

 

Joe

 

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The Black wire (with the 'C' connector lug) is the dedicated ground wire for the HVAC mini-harness.  On my 70 Z, the lug is secured by one of the lower mount bolts that secures the dash centre frame legs to the transmission tunnel.

 

The Red wire is the main power 'IN' for the HVAC mini-harness.  The male bullet connector plugs into a matching female bullet that you'll find at the end of another red wire coming down from the dash harness on the right side of the centre stack.  This red wire is distinguished by an in-line fuse holder (that should have a cartridge fuse with 30A rating). According to the FSM wiring schematic, the wire leading into the fuseholder is Blue and the wire coming out (the one you're looking for) is Red.  On my car, both the entry and exit wires for the fuseholder are Red.  The Red entry wire ties into a Blue wire somewhere upstream in the Dash harness.

 

The Green wire emerging from your Blower switch is not stock.  It was undoubtedly added by the A/C installer (who didn't realize that the taped-back Blue wire is there to fill the same purpose  -- i.e. provide switched power for an add-on A/C system).  If you decide to keep the Green wire, there's probably no need to concern yourself with the Blue wire (or vice versa).  One makes the other redundant.  The only possible difference between the Green option vs the Blue option is that the Blue wire may offer not only ON/OFF function, but also 3-level speed control.  I haven't checked this yet with my harness.  However, it seems possible, because the Blue wire emerges from the 6X connector where the HVAC mini-harness plugs into the rheostat block in the Blower housing. 

 

My guess is that your added-on Green wire offers only ON/OFF.  However, that may be all that your particular A/C system needs to make it work.  Others with more experience with dealer-installed 240Z A/C systems may be able to comment with greater certainty. 

 

FYI, the only diagram I've been able to find for the 240Z's HVAC mini-harness appears in the bottom RH corner of Figure I-2 of the 'S30 Supplement Chassis Manual' (easily available online -- there are links to this elsewhere in the Forums section of this site.  Use the 'search' function).

 

The FSM wiring diagram labelled, '240Z (Late model S30 series U.S.A. - manual and automatic transmission' has an accurate (but not necessarily easy-to-understand) depiction of the HVAC mini-harness connections.  You'll see the Blue wire clearly marked as, 'AIR COND POWER'.

 

Hope this helps.  Use caution when powering up for the first time.  Be sure all fuses are in place and of proper rating, and make sure that the engine harness is properly equipped with 'black' fusible links at both the Starter and Alternator locations.

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Thank you so much this really help because i am 15 trying to fix up this car my dad has had since 88 and i do not want to make any mistakes.  The blue wire that is taped to the harness, do you know where it goes to?  I cannot find a male connecter for it

 

Joe

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Joe, the reason why you can't a male connector for the Blue wire is this:  240Z's did not come with factory-installed air conditioning systems.  The air conditioning system was installed by someone in the USA after the car arrived off the boat from Japan.  That 'someone' was probably the dealer who received your car back in 1971 as part of their new-vehicle allocation from Nissan.  It might also, perhaps, have been installed-to-order for one of the previous owners by an air conditioning shop.  It might even have been installed by a local garage, or even by the owner.

 

In any case, whoever put the air conditioning system in your father's car didn't know about the hidden Blue wire on the car's HVAC mini-harness.  All they knew was that the A/C system they were about to install needed a 12V power wire with an ON/OFF switch.  The ON/OFF switch was already there (in the form of the Blower switch), but the wire wasn't.  So they simply soldered on one to one of the POWER-OUT terminals on the back of the Blower switch.  To avoid creating confusion with any of the factory-installed wires down in the same area (none of which are green), they used a Green wire.  Then they connected the other end up to the control wire that provides power to a thermal switch that controls the electromagnetic clutch on A/C system's compressor drive.  You can find that wire up in the engine compartment by tracking backwards from the A/C compressor (which is the bigger of the two 'cans' that are powered off the drive belts at the front of the engine  -- the other 'can' is the alternator).  When you find a likely looking wire, track it back to the thermal switch, and then track back from there towards the firewall.  Check the colour of the wire at the last place where you can see it in the engine compartment.  (Hopefully) the wire will stay the same colour in the Interior all the way to the place where the Green wire used to connect to it.

 

So:  Go back inside the Interior and look for a same-colored wire that's: 1) within reach of the disconnected Green wire, and; 2) not connected to anything else.  It'll probably have the same kind of end connector that's fitted to the loose end of your Green wire.  Based on your picture, that means you're looking for a male spade connector.

 

One caution:  There's always a chance that the A/C installer got creative/lazy/frustrated and used a completely different color of wire on the Interior side of the firewall.  If this turns out to be the case, all you can do is look for a loose wire-end (probably with a male spade terminal).  When you find a candidate, you should check to see if it's really the A/C controller wire by using a multimeter (or even just a test light) to confirm that 'loose end A' (the one in the Interior) does, in fact, connect to the A/C compressor clutch wiring up in the engine compartment.

 

Once you've found the right wire:

 

If you decide to get rid of the Green wire coming off the Blower switch and, instead, use the factory-provided Blue wire, then you'll need to cut the male spade connector off the end of the A/C control wire and replace it with a male bullet connector.  Now it will plug into the factory Blue wire.

 

Just to be completely clear:  If you keep the Green wire, then you don't need the Blue wire.  If you decide to use the Blue wire, you can unsolder the Green wire from the Blower Switch and throw it away (the wire, not the switch).

Edited by Namerow
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Thank you so much, this clears a lot of questions not knowing how things go.  This is the second time that the entire intereior was stripped and the first time it was it sat for almost 8 years b4 putting everything back and he remembered everything and this time it sat for almost 8 days and we can't remember where it goes.  

 

So,  the A/C control wire is the wire that comes from the A/C compressor and I can cut the end off and put a male bullet connector to connect to the female blue wire from the HVAC harness and eliminate the green wire, correct?  And the green wire that was added on was in fact a male NOT a female spade connector.  So i am looking for a female spade connector to cut off and add the male bullet connector.  Basically how and where can i find this A/C control wire that connects to the blue female bullet connector wire from the harness? Thats all i need to know at this point.

 

Thanks for all your help,

Joe

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Explained in my earlier post, but here it is again:

 

The A/C control wire provides power to a thermal switch that controls the electromagnetic clutch on A/C system's compressor drive.  You can find that wire up in the engine compartment by tracking backwards from the A/C compressor (which is the bigger of the two 'cans' that are powered off the drive belts at the front of the engine  -- the other 'can' is the alternator).  When you find a likely looking wire, track it back to the thermal switch, and then track back from there towards the firewall.  Check the colour of the wire at the last place where you can see it in the engine compartment.  (Hopefully) the wire will stay the same colour in the Interior all the way to the place where the Green wire used to connect to it.

 

Then:  Go back inside the Interior and look for that same-colored wire.  Clues: 1) it should be lying somewhere within reach of the disconnected Green wire, and; 2) it won't be connected to anything else.  It'll also probably have the same kind of end connector that's fitted to the loose end of your Green wire.  Based on your correction of my earlier note, that means you're looking for a loose wire with a female spade connector on the end.

 

New note:  There's always the possibility that your dad found this A/C control wire during his earlier efforts and, not knowing what it was for, taped off the end and stuffed it up somewhere out of harm's way under the dash.  You never know.

Edited by Namerow
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and when i find the female spade connector i can cut it off and put a male bullet connector to connect to the blue wire.  How come they wouldn't have the wire already a male bullet connector to connect to the factory blue wire thats already there, instead of having to change it?

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The wire you're looking for (that is, the wire that comes through the firewall) wasn't installed by Nissan when it built your car.   It was installed by the person who installed the 'aftermarket' A/C system in your car.  That person would have used whatever color of wire and type of connector they had available.  This, of course, is the same person who soldered that short, add-on Green wire onto your car's Blower switch.  Chances are that they used more of that same Green wire for the longer run from that goes from under the dash and through the firewall into the engine compartment. 

 

Or maybe they used a different colour of wire.  We don't know.  

 

It's a pretty safe bet, though, that they used a spade connector for the end of the wire that's (hopefully) hiding somewhere under the dash.

 

There is one other possibility, though, and you need to be aware of this:  The wire you're looking for (the one that goes through the firewall) may have been stripped out of the car by someone who got there before you or your dad started working on the car.  I don't know why anyone would do this, but it's a possibility.  If you can't find a likely-looking wire, then you'll have to put in your own (not a big deal) and figure out how to hook it up to the A/C thermal switch in the engine compartment.  My car doesn't have A/C, so I can't tell you what to look for at the switch end.  Anyone else want to jump in here?

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  • 2 weeks later...

Some further insights into wiring for a dealer-installed aftermarket A/C system, as posted by member 'AZ 240z' on 21 January 2014:

 

"The dealer added FrigiKing air conditioning incorporated a micro-switch that may have utilized one of these wires. The micro-switch was mounted at the intake duct actuator located behind the blower motor in the passenger side footwell area behind the dash.

 

When the top slide lever on the heater control panel was moved from the center "vent" position to the left "off" position, the intake duct door moved to close off fresh air intake and open to allow the air from the evaporator to pass through the blower assembly for cabin distribution.

 

Also, with the movement of this vent lever to the off position, a circuit was completed via this micro-switch through the dealer added A/C ON-OFF/ RHEOSTAT switch to allow electrical actuation of the A/C compressor. This on-off switch was mounted to the bottom of the dash below the hazard switch.

The micro-switch assembly on my car is incorporated in a red plastic housing mounted next to the cable actuator for the intake duct behind the blower motor."

 

I believe that the FrigiKing A/C system was just one of the two or three different aftermarket systems that were installed by Datsun dealers back in the day.  The choice of system may have depended on the sales region, or it may have been simply up to the individual dealer (carl Beck would probably know more on this).  They probably all operated and were wired in much the same way.

 

So:  The wire connection point you're looking for may, in fact, be at the microswitch that is, "mounted at the intake duct actuator located behind the blower motor in the passenger side footwell area behind the dash."

 

I wonder if anyone else has ever posted a wiring diagram for one of these aftermarket A/C systems?

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