AC fan works fine. Temp gauge seems to work fine. Both AC and rad fan relays are OK (switched to test). Tested rad fax with 12 V - works fine.

But the rad fan never comes on. On hot days in traffic the temp will go over 210. When it gets near 210 now, I use the AC and the AC fan brings the temp right down.

But I'd like to get the rad fan working properly. My Gates manual is useless for this diagnostic problem.

Looking at the schematics, it seems that the temp switch runs to the main computer. Does the computer control the fan or does the thermoswitch do it directly?

Anyone got any ideas? This is really getting to be a pain to figure out.

Thanks...Steve.

there should be 2 sending units one for the gauge the other for fan turn on (I think) the computer on the '97 turns on the fan so I think it would on the '96

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Steve
'97 GTP VS cam, ZZP PCM, and not much else yet

My rad fan wouldn't come on until the temp hit 230. Why the factory set the car up this way I have no idea. Why the thermal switch goes into the computer and not the fan relay I also have no idea, but I didn't feel like reprogramming the computer, so I got a $27 Flexalite adjustable thermal fan switch from Summit. Came today and took an hour to put in.

Job is easy as can be. Run an "always on" power source to the switch and cut into the light blue wire to use the factory fan relay. Put the probe in the bottom of the rad (in the fins, not the water passage). Turn on the car, set the switch to have the fan come on at 200 degrees (5 degrees after the thermostat opens) and JOB DONE.

Works perfectly. Now I can sit in traffic all day long, if I have to and the temp never oes above 200.

Everyone should do this $27, 1 hour fix. You'll never worry about your climbing temp gauge in traffic again.

Boatman.

Because it makes sense? That way the computer can monitor the fan's operation and easily control when it should be on or off.

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2004 Impala LS - got some mods
NAIOA Moderator

If you think it's a great idea to have your computer only turn on your fan in traffic at 230 degrees, by all means, leave you car the way it is and enjoy your toasty engine in traffic.

If you know about the wiring on these cars, you'd know that the computer does not check the temperature of the coolant in the radiator, the factory thermal switch is in the block. I left that switch and wiring intact so the computer still knows what the temp of the coolant in the block is. I just set up a parallel system to keep the engine cooler in traffiic than the 230 degrees the factory intended.

Boatman.

I never said what they had it set to was a good idea, just that it's a good idea to have the computer control and monitor it.

Yes, I know that, and it's how it should be.

I wasn't playing down your solution. You asked "Why the thermal switch goes into the computer and not the fan relay I also have no idea," and I gave you the answer.

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2004 Impala LS - got some mods
NAIOA Moderator