Cooling fan and cooling issues


New Member
Jun 6, 2009

Just got my new car here in Scotland (87 T).

Have some overheating issues (annoying since the car came from Florida). I have flushed the radiator vigorously. Not much crap came out but 3/4 filling it shows water flowing through the upper core. I suspect the water pump may be a bit weak. Are there any tricks or things to watch on swapping the pump ?

I have a TT chip and it turns the fan on at 165, but, at idle, the fan was struggling to keep the temp at 170-175, and after we went for a drive, it hit 190, which is way too much. My old GN used to cut the fan on at 180 and off at 160 and could pull the temp down quite quickly. I assume that the TT chip does it differently by trying to hold the temp near 165? Assuming a 160 degree thermostat, the car will drive around fanless at 160, and cut the fan on at 165. Is this a correct assumption.

Now, regarding the fan wiring, there are three wires going from the connector to the fan. One is the earth and the other should go to either side of the resistor. On the car, both go to the fan motor side of the resistor. My assumption is that this means the fan runs on high, no matter which relay is triggered. I am not sure if this is because the resistor has failed (I measured it at about 1 ohm - is this correct?) or the car really needed the fan on high all the time.

I know that one relay has a black/pink wire (the low speed) and one a black/red (high speed). I would think that the black/pink goes through the resistor and the other to the motor side of the reisistor, but the wring layout makes that seem impossible due to the nature of the wires and connector rings.

Also, for some reason, the two green wires coming from the pressure switch on the a/c were twisted together (shorted out) :rolleyes: No idea why that was done but I have separated them now.

I have attached some photos.

Any help appreciated. The car really does fly though ... shockingly quick. Smoke city. :biggrin:

All the best


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From the factory these cars came with a 195 thermostat. I would not worry too much unless it starts to climb above 210.

Pretty common to bypass the fan resistor when it goes out. The fan will run on high no matter what relay is closed.

If you have a Extender chip, the ac wires may have been connected to change a setting. If the ac is not working and you need to change chip setting, you would jump these two wires together to trick the ecm into thinking the ac was on. Just a thoght.

Good luck with the new toy! :cool:
hello people; You take some purdy pictures. I was just going to talk about cooling as I just shot my load on that high dollor Griffen rad. with a 160 stat and a TTchip. It was done at Cottons so everything is done correct but (if you can believe the gage) my readings are about 180 to 160 depending on the conditions. My fans aren't comming on at the temps your talking about and if the are I don't think that's correct.
I just got the car back and there's a new learnig curve.
But maybe you can try that cooling additive people here talk about. I think I might. To be truthful I'am going to drive the car and see what happens and not go crazy worried about the temps.

The car has a Translator Plus, so it may have had an Extender chip. I have unjoined the two a/c wires.

Does anyone know what the reisitance of the resistor should be? It isn't open circuit, but it would be good to know what it should be and I can revert to 'normal' connections.

195 degrees seems high to me, although it was stock. There is a 160 degreee thermo in it so I would hope that, driving around, the car should run at 160-165 degrees. Instead it climbed, and kept climbing.

What I also can't understand is that the top rad hose was hot and the lower one was much cooler. Either the radiator is super efficient, or there just isn't much flow through it.

All the best
FWIW, I completely bypassed the low speed resistor. Now when it kicks on it's on high speed only. I like that much better.
The resistor is well under 1 ohm so you are probably measuring it okay.

I think it's around .35 ohms or so.

A search in tech. probably will find the exact answer.

It only drops it a few volts for low speed.

There is a 2 wire and a 3 wire A/C switch.

The two wire passenger side should go to the drier tank switch it is the low pressure cycling switch, blue and green I believe are the proper colors.

The 3 wire switch is on the high pressure side drivers side of the car, and run the fans also, low and high speed grounded triggers to the fan relays at pressures only seen when the A/C is on and pumping.

Make sure the rubberized thin shroud thingy is under the radiator too.
By the looks of the wires on the resistor, looks like someone has already bypassed it unless I'm seeing it wrong. I like mine on high speed when it kicks on.