90 TR Question

You may have lost your A/C charge due to a leak. Have your shop put the gauges on it to read the pressure in the system.

Are you also saying the the heater/a/c blower fan is not operating either?? Try putting the fan speed control all the way to "high" to see if the fan comes on. If it does you may have the small fuse blowen in the controler itself (located under the center console in the fan speed control unit) or you can have a bad fan speed resistor located inside the airbox assembly. The connection can be found under the right side of the dash just forward of the center binnicale. You must remove the side trim panel. Its a three pin connector with yellow orange and red wires going to it.

 

Unplug the "k" white connector at the bottom of the relay/fuse panel. If the 2nd pin from the right looks like the one in the photo you've found the problem

Another (less likely IMO) possibility is the "G" AC relay -- as a test, just swap a different ...113 relay (from another function) into that relay position.

(The blower fan should always work -- even if the compressor isn't working because of losing the refrigerant charge. But put the blower fan speed control at maximum just to keep the power transistor out of the picture.)
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I got individual connectors from Wade at FCI. The reason why we always replace them is because the heat reduces the temper and they no longer "spring" closed, which is required for a good connection.

-Peter

 

The fuse doesn't blow because the problem is the current density at those connectors and not the current magnitude -- i.e., the 15~20A current that it takes to run the whole AC system doesn't blow the 30A fuse, but it causes a lot of I^2*R heating at that connector (even for a fairly small contact R) -- which raises the R even more (both because the material in the female pin loses it strength, as Peter mentioned, and because the surfaces in contact gets oxidized at the high temperature). The higher contact R causes even greater I^2*R heating in a death spiral until either the male pin, PWB, and/or the female pin just get so frazzled that it stops working.

For the AC, what you need to do is provide a high-current capable connection from the 87 terminal of the AC relay out to those M (brown) wires in the k connector. Depending on the damage there are several approaches:

1. If the male pin and PWB are still in fairly good shape (or can be refreshed), just replacing the female pin in the connector every few years might work.

2. Replacing both the female pin and the fusepanel PWB will get you back to the stock situation, but this is somewhat expensive (and you'll still eventually have the same problem if you don't regularly refresh the female pin per Peter's suggestion).

3. If the male pin or PWB are damaged beyond repair (which was my situation), then you need to somehow add another high-current capable wire connecting the 87 terminal of the AC relay out to those M (brown) wires in the k connector.

The quick (but maybe a little crude) way to do #3 is to just attach/solder a large wire directly to the 87 tab on the AC relay close enough to the relay body so that the relay can still be plugged in and make contact with the other terminals on the PWB (that's the top photo below from Ben L. -- that's not the AC relay but it shows the method) and then splice the new wire into the brown wires. I also did the #3 repair, but I added the new wire inside the fusepanel itself from the 87 terminal then out to the brown wires. In the second photo, the yellow wires are for this new AC connection (I used two wires in parallel because there are two 87 terminals on a ...113 relay), and the blue and blue/black wires are for the fuel pump connections which I also bypassed (and then later I even had to bypass both water fan connections). The 4th photo shows how the yellow wires splice into the brown wires and how the blue and blue/black wires splice into their respective wires going to the fuel pumps (I added inline connectors so I could still unplug the fusepanel as a unit).

The 5th from the right connection in the "k" connector (2 AN light blue/black wires) is for the LH turn signal lights. If you can't do option #1 for that problem, give a shout, and I'll see if that connection can somehow be bypassed with an added wire.

Good luck!
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Nice fix, Steve. I've got the same problem on a customers (white) '90 TR here now.

-Peter

 

Thanks Peter -- I'd have to bet that virtually every TR will have some version of this problem on the connections for the higher current gizmos eventually

Bill -- No trouble -- glad to pass on the information. I can't really help with the connector sourcing because my damaged male pin & PCB didn't really allow me to try that route (and on the fuel pumps and water fans I wanted something more reliable than the stock situation). The floor vent ECU does use the same +12V coming from the M (brown) wires so it would/should be "dead" if you're not getting +12V onto the M (brown) wires.

 

As Lolaman said, Wade has taken the time to find the OE parts through Fiat (Ferrari wants you to buy the whole front harness), call him, he has them in stock.
Last ditch effort to save the fuse box is to solder the wire directly to the male spade in the box and run the wire through the connector with an external connection 4"s out from ther plug. When you are there prepare to do the starter wire, A/C wire, Cooling fan wire..... they all have the same problem
Steve has to be the most consistantly accurate information source on this board. Nice work!

Dave