I made one from sheet metal to fit the XJ radiator. Utilizes all the fan and is enough to cool the engine on a hot day without the aux fan. Thinking I might be giving it up one of these days and to to a more square radiator
Howdy! I had a brain fart.
Since I no longer have the factory mechanical fan, and my electrical ones only come on when the temp is high enough to be commanded by the ECM. Or my override toggle switch is on. I want another option.
I know normally the AUX fan comes on when the A/C is turned on but it gets the command from the ECM. But it won't come on now if I put on the A/C. The ECM also gets an input from the A/C low pressure switch, but I removed my A/C compressor to make room for the alt relocation and Taurus fan. The plug is there for the switch, but since it's not hooked up, the ECM thinks the A/C charge is low and will not activate the compressor or fan. If I can fool the ECM to think the A/C is fully functional, then any time I turn my A/C on, the ECM should command the AUX fan to come on. Not worried about the compressor clutch since the ECM just sends a ground signal to the relay. It looks like the A/C low pressure switch and the A/C cycling switch get power from the A/C blower control. If I just jumper the low pressure switch, that should cause the ECM to turn on the AUX fan. At least that's my hope. I have included the wiring diagrams, just looking for some input. What say younz?
Gluck, I solved this by running a parallel circuit. I got a temp sensor from Painless Performance wiring, drilled the manifold and set it up so that the new fan circuit fed the same wire as the OEM circuit. Then you don't have to mess with fooling relays etc. Also I found that the Taurus fan pulls about 80 amps on start up if you start it on high speed and I was frying 50 amp rated relays. For the same price I got a golf cart relay, looks like an old ford solenoid, and used that. No heating problems then. The Taurus fan pulls 37 amps on high speed, So if you run both you will be pulling about 50 amps.
Dude I think you missed the point. I want to control the stock AUX fan, not the Taurus fan. My circuits for the Taurus are 40 and 100. I want to just turn on the AUX fan by itself by using the A/C override that would normally kick the AUX fan on when A/C is on. currently the AUX comes on with the either speed of the Taurus. Thanks
No, I didn't miss the point. You want to control the aux fan. As I said, a parallel circuit. The rest was just added info based on my experience. If you mess with the fan circuit, it will give you a CEL
Well I finally got a chance to jump the low pressure switch. With the a/c on, it will command the fans to come on regardless of engine temp. Which is normal. Problem is, it also turns on the Taurus fan, since I use the output from the ECM to automatically turn both fans on when it gets hot. I now understand what you are referring to 4.3, apologies. A parallel circuit separates the control. I will have to dig into this a little later. Since winter is approaching and overheating should not be an issue. And I have too many irons in the fire.
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