Jump to content
HybridZ

A/C and heater switch wiring


Grog

Recommended Posts

After carefully studying several electrical diagrams of the Z's heater and A/C wiring, it was apparent that none of them matched what the wiring color codes in my 1975 Z was. They are still stock. I could smack the engineers at Nissan for sniffing glue on the job, because that's the only explanation I have for the wiring mess they concocted. Maybe that's what the engineers who designed the timing chain cover for a Buick V8 did also. :shock:

 

Question: I know where the blue/yellow, blue/red, and blue/green wires go (fan switch to resistor pack) and the blue/white also (fuse box - i think...) but there is a blue wire and TWO blue/black wires (one is 16/18 gauge, the other 12 gauge) that run from the resistor pack to God knows where. Where do they go? Does one of them go to the blower motor? BTW, I am using the fan from an 88 CRX and it works great. I digress....has anyone deciphered this wiring mystery because I sure couldn't do it. :twak:

 

Also, has anyone made their own resistor pack to replace the aging (mine is more like decrepit) resistor coils and would have some good information/part numbers/instructions on doing this upgrade?

 

I am re-wiring my Z using parts from Waytek. The last bit I have to wire up is the heater and A/C controls, which is giving me a fit because none of the wiring diagrams I have is accurate.

Link to comment
Share on other sites

  • 4 years later...

I share your pain. It is truly a mess to try to figure out. And presently, I am trying to get my heater fan to come on so that I can test the rest of my system. I did the Delco/Remey Alternator swap. Tossed the fusible links and Voltage Regulator as far as I could throw them. Then did some re-wiring while installing the Maxi Fuseblock conversion. Also replaced 2 gauges in the dash with SW direct gauges so, no electrical connection. All fuses and voltages in fuse block have been checked good with about 12V across most of them. Everything appears to work fine. Great idle and all. Except... No Fan ! Can't do any ECS tests without it. Suggestions anyone ??

Link to comment
Share on other sites

I had a similar problem with my Z charging system. I replaced my voltage regulator,alternator, starter, battery, ACC relay, replaced leads to the battery and nothing happened. My heater fan used to work, so i wanted to test it to see if it was still good. I took the two wires coming out of the fan motor black/yellow i think and connected them straight to the battery and it worked. so i knew the motor was good and found out even though i didn't have a radio, the fuse needed to be in for the acc relay to work!

Stupid mistake but the parts needed to be replaced anyway. So supply 12v the motor and i'f it works it's in the wireing.

Link to comment
Share on other sites

Thanks for the reply. Yes, I supplied 12V directly to the fan motor (Blue & White wires) and it fired right up. Also have 12V showing right across the fan fuse in the fuse block. Verified continuity through the switch. What I did find this weekend was a completely fried set of heating elements (spring type resisitors) up in the blower housing. They were burnt so bad that half the board was gone and solder had melted on to the fan cage below. So now, if that is fried, will that stop voltage from ever going thru the switch and where on earth could I possibly buy one ? MSA doesn't list it in their catalog. I would even consider leaving it out if someone knows how to straight wire past it.

Link to comment
Share on other sites

What I did find this weekend was a completely fried set of heating elements (spring type resisitors) up in the blower housing. They were burnt so bad that half the board was gone and solder had melted on to the fan cage below. So now, if that is fried, will that stop voltage from ever going thru the switch and where on earth could I possibly buy one ?quote]

 

Yes, the wires going to the resistor inside the blower motor housing are directly connected to your blower control switch. There should be 5 wires leading to the resistor mine are blue/green, blue/black, blue/red, and two blue wires. One of the blue wires comes from the fan motor and the rest are leading to the blower control switch.

I have a good condition fan motor housing with resistor i'f your interested. I can take some pictures of it if you want, let me know.

Darren

Link to comment
Share on other sites

I don't have a CLUE if it will help, but I have a collection of at least two different wiring diagram sets for the 75 280Z that I could email you. There are several jpegs and gifs, as well as a couple PDF files. I know one diagram is an FSM style, and the other is a very clear and easy to read re-drawing that I believe may have come from a chilton's manual. I have NO clue how identical the diagrams are, but if I were to find a discrepancy I would lean towards trusting the "FSM one."

 

PM me your email address and I can email them to you; they probably won't be any help, but it cannot hurt.

 

 

My Subaru forum has some great info on rebuilding blower motor resistor packs. http://www.ultimatesubaru.org/forum/showthread.php?t=75738&highlight=resistor+pack

Link to comment
Share on other sites

This is great info. Thanks a bunch. I just gotta ask, do I also have a fan relay in my '76 280Z 2+2 ? I might even entertain straight wiring(bypassing) the resistors(heating elements) if anyone has any ideas. I live in the South and can definitely wait until the engine warms up for any warm air.

Link to comment
Share on other sites

If someone can tell me what the Ohm rating is for each of the resistor spring elements, I will just go to Radio Shack and get the resistors and solder them in place. That way, I should get the benefit of getting my fan speeds back and won't get any warm air until the motor warms up. Where I live, the A/C is much more important anyway. But, I will need those fan speeds for that. If I'm thinking right, this idea should work without burning anything up.

Link to comment
Share on other sites

When the ignition is on, the blue or white wire going to the blower motor should have 12v after you switch it on. Find out which wire has 12v to it(blue maybe) and the other whire should be dead w no voltage. This is the wire you can use to connect a simple switch to. Connect the dead wire (white maybe)from the motor to one side of the switch and ground the other side of the switch. Then turn on the ignition make sure the fan motor switch on the dash is switch on, and then flip the new switch you put in. It may only be one speed but it will work fine. Also if your going to RadioShaq get a Varistor or Rheostat switch and hook it up the same as i told you and you can adjust your own speed of the motor. I drove for 13 hours to get here in New Mexico and have to work today so i'll get on later to see how it went.

Link to comment
Share on other sites

  • 7 months later...
When the ignition is on, the blue or white wire going to the blower motor should have 12v after you switch it on. Find out which wire has 12v to it(blue maybe) and the other whire should be dead w no voltage. This is the wire you can use to connect a simple switch to. Connect the dead wire (white maybe)from the motor to one side of the switch and ground the other side of the switch. Then turn on the ignition make sure the fan motor switch on the dash is switch on, and then flip the new switch you put in. It may only be one speed but it will work fine. Also if your going to RadioShaq get a Varistor or Rheostat switch and hook it up the same as i told you and you can adjust your own speed of the motor. I drove for 13 hours to get here in New Mexico and have to work today so i'll get on later to see how it went.

 

Hope 6 months old isn't a big no-no; figured since the 2nd post is 5 years after OP, I'd be OK... (I searched, I promise!)

 

I have a '78 280Z and the heater fan won't turn on via the switch. I've checked all fuses and replaced ones that looked dodgy, cleaned contacts, took off plastic panels and done hand-over-hand on wiring going to the heater and switch, etc. The mechanical action of the lever to the switch works fine, and it sounds like the contacts inside have positive engagement.

 

If I hook 12v from the battery directly to the motor, it fires up. As near as I can tell from wiring diagrams and descriptions, all the switch does is ground the fan; is this true? In that case, I might just do as the above quoted poster suggested and just put my own switch in. I'd like to fix it correctly, though. Has anyone ever pulled the switch out and replaced it? It looks like it'd be a huge PITA to me. The plastic panel is easy enough to remove, but the switch seems to be bolted very securely in place, buried behind the metal frame.

 

Any help would be appreciated.

 

-Stephan

Link to comment
Share on other sites

  • 3 weeks later...

Bought a new complete fan motor with housing and resistor pack, supposedly off of a 78 280Z (eBay). Got it and it looked fine. Pulled my old one off and after dumping a metric butt-ton of leaves, rust, and assorted debris onto the floor, I compared it to my new one. Uh-oh. Unless Datsun decided half-way through the 280Z cycle to make a new connector for the resistors, I got something that is decidedly NOT from a 280Z. 280s have a 5-pin, 6-hole connector on the resistors, with two little plastic tabs on the sides. The one I got only has 4 pins, 4 holes, and no tabs.

 

Looked at it for awhile, figured the circuit should work outside of the fan housing, so I unscrewed my old resistor pack, which was actually in *better* condition than the new one, and hooked it up. So, summary: new motor was hooked up to power, old resistor pack was hooked up, left dangling.

 

No go. Nothing at all. So all I can figure is that the fan motor is not getting power. Unfortunately, I don't have a DMM, so I can't verify that right now.

 

Does anyone have any other ideas? The only thing I didn't do is actually start the car. I figured with the key turned to On, everything in the car should have power. (buzzer sounded, gauges reacted, etc.) Am I mistaken in this?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...