[i4abuygto]

Hello guys,
I am looking for help to find the location in the car where the wire that feeds the relay for the fan switch gets its 12volts from the ignition feed.
On my 79 TA, I am working on putting in the new heater core, and fan. I have installed the fan with new resistor, and I have all fan speeds except the high speed which works through the high-speed fan relay.
I have 12v power from the high speed switch setting into the relay (grey-Black) wire but I dont have 12v on the 12gauge red wire that feeds power to the relay from the battery or ignition circuit. See attached photo.
Where in the car is the place that the 12 gauge red wire picks up 12 volts from the battery?
I believe I either have a blown circuit or the wire is disconnected.
Thanks in advance for your help

[bhill86]

That wire comes right off the back of the alternator

[gtohurstjudge]

What happens to this setup is that the wire coming off the
back of the alternator has a snap splice connector in it where it crosses
over the middle of the right valve cover. This snap connector can't handle the power load and it burns up causing no power to the relay. the fix is to cut
out this connector and solder or crimp the wires together.

[i4abuygto]

Thanks guys - I will look for the splice that you are talking about by tracing the wire from the alternator. So does that mean that this wire isnt fused or on a protected circuit?

Does the car have to be running to get the 12 volts off the alternator as all my testing has been done with the engine off.

[bhill86]

No, engine does not need to be running.

[i4abuygto]

The 12 gauge red wire off the back of the alternator has 13.5 volts. that Alternator wire harness goes along the base of the left valve cover and goes down the rear of the engine.

I found no wires coming over or around the right-side valve cover. After following the wire off the relay - I did find an off white / clear color push connector that has been cut off and dead ended after the connecter so no idea how that was routed or connected to the alternator. Therefore, no power to the fan relay.
It looks like several wires for the AC system along with the relay wire have been left to hang loose. I will have to figure all that out as I want to get the AC system working again.

To get 12 volts to the relay, Can I just splice off the 12 ga. wire at the alternator and run another 12 ga. wire to the fan relay. If so does it need to be fused?

Thanks

[bhill86]

Yea, originally, that wire had a fusible link.

[bhill86]

I sent you a PM

[i4abuygto]

Thank you for the PM- I will run a fused 12 ga wire from the alternator and start looking into what I need to do to get the AC system back working.

On a side note - the fan in the car seems to work well (minus the high speed). With everything exposed should I put in a new fan motor?

[Trevor78]

Full speed on fan is bypassing the resistors, so you already know the fan works. Could be the switch or the wiring if your know it and the AC side is already faulty or incomplete.

[Trevor78]

Forgot to say, the high-speed relay is on the AC case, so if that is all missing/unplugged, it may be one reason, although you have resistors working somewhere for other fan speeds.

[i4abuygto]

All works good - I had to bypass the relay to get the high speed so I will order in a new relay.
I will rephrase my earlier question about the fan. If the existing fan works is there any need to or do you recommend replacing it as I have the fan exposed now with the heater core install and these are a PITA to get to.
On the other hand the existing fan is working good and there is no guarantee that a new fan will last any longer.

[bhill86]

Your last sentence is the approach I could take but that’s just me. One could argue either way.

[burd]

Replace the fan if you got it all apart.

[i4abuygto]

I am looking for a new 79 hi speed relay - does anyone have a part number?

Or, do all AC systems in 79 have the automatic temp control. The automatic temp control system calls for a different relay than the non ATC.

[bhill86]

Nearly positive when I replaced mine I just used one from this parts store. Been in for several years with no issues.

https://www.oreillyauto.com/shop/b/a...er+motor+relay

No ATC in firebirds

[Warren Seale]

If you want to keep the original connector for the blower motor high speed power feed, I managed to come across a lot size of 1 terminal Delphi/Packard 08917583 female connector housings. This is the connector that is commonly used in the late 70s for the high speed blower motor power feed that sits near the A/C compressor. It typically gets melted from overheating. I'm going to sell these in small quantities if anyone needs them. I'll post this in the Parts for Sale section. Here is a description of it.
https://www.connectorpeople.com/Conn...ARD/0/08917583

[i4abuygto]

I am looking to add the fuseable link wire from the alternator to the high speed fan hook up on the harness.
I believe the attached photo shows the high speed fan connector red wire and stock connector.
It looks like I will need the mating connector if that is the one that Warren is selling.
Can someone send a photo of the fuseable wire that comes off the alternator and its mounting location in the car.
Does it run along the passenger side valve cover to the fan relay location?
Is it just a 12 gage fusible link with eyelet on alternator side and the female connector on the fan relay side?

[bhill86]

My 77 service manual shows 18gauge fusible link.

[i4abuygto]

My 77 service manual shows 18gauge fusible link.

Thank you.


The red wire at the fan relay on my existing harness is at least as heavy gauge as a 12 gauge and might even be a 10 gauge - it is a large wire- much bigger than 18 gauge.
Perhaps that is why some of these connections are over heating if the wire is to small for the current draw. You would think the fusible link would come apart before the terminal melted.