midwest2

The front electric aux. fan attached to the A/C condensor is running constantly on my 96 LS400. I'm guessing the problem is the temp sensor located on the bottom driver's side of the radiator. Has anyone else had a similar problem?

Banshee365

Do it run continuously with the A/C off?

midwest2

Yes, the hvac is completely off and the fan will start with the first cold start in the morning.

pmesfun

The fan is driven by the "drive" belt, it's always running.

midwest2

I always love getting responses like this or when I see others get them. I clearly stated my "electric auxiliary fan" was on all the time. (I guess I did abbreviate auxiliary) The fan is not driven by the drive belt and will turn on even when the engine is not running if the key is turned to the "on" position.

Banshee365

IIRC if you disconnect that temp sensor the fan will run, that is a way to test it. Either you have a problem with the connection or, as you said, the temp sensor could be to blame.

My '96 only has 1 fan, many LS's have 2. I always thought that was odd.

parkerjs

A bad temp sensor is more likely, but just in case that's not the problem it could potentially be a relay stuck closed.

midwest2

Thanks for the info, I quickly scanned the owner's manual and I couldn't identify which relay controls the fan. I will change that first and then the sensor as a last resort. Like most things on this car, that sensor isn't that easy to get a tool on.

96DWPLS400

Bumping this old thread to see if anyone can help with the proper resistance readings for the ect switch (located at the bottom of radiator on driver's side). I've been through the fsm and can't find a test procedure.

When removing from the radiator I grabbed hold of the connector and started turning to unscrew it. That resulted in some grinding like noises and only then did I notice the nut at the base. Before just replacing it I'd like to test it to see if it's still good or if I broke it.

So either a test procedure with the proper resistance readings or a shove in the right direction on where this would be in the fsm would be appreciated.

96DWPLS400

Found it - gonna leave it here for others.

CELSI0R

If I recall correctly, all 1990-1994 LS 400s came with two electric fans. 1995-2000 only had 1.

I think the A/C Receiver Drier is in the way on all UCF20/21 models

ImEbo

hey

i’m working on ls400 96 project

just wondering if your electric fan is running

mine rn not sometimes when i turn on auto ac it dose wondering under what condition should it work and after replacing the ect switch did it worked ?

96DWPLS400

Mine worked both before and after changing the switch. My problem was that I broke the switch when trying to remove it from the old radiator when changing the radiator. What I deduce from the test procedure is that the function of the ect switch is to turn the fan on when coolant temperature reaches somewhere near that 199 degrees mentioned in the test procedure.

ImEbo

dose it work when turning ac or just when the temperature reaches 199

i fount out mine only works when i press the auto ac mode