Atrofee

I thought I would find a previous post but cannot. Pls Advise

Im familiar with the RDI Relays underneat driver heatlight. Since they each have a RDI this is not the problem. AC ON = fans still dead.
Also can someone explain the stock fan design. Im assuming that these are electric fans but I read that a clutch might be used or a fan driven by fluid?

matchesLS

Two fans, one electric pusher fan and one viscous fluid/fan clutch that is driven by the drive belt. The electric is an auxiliary fan that turns on and off depending on temperatures. The drive fan does the same thing, when the fluid inside the clutch gets hot enough, the clutch engages and turns the fan blades. The auxiliary fan doesn't always run with the A/C on. How do you know that they are bad? What symptoms does your car have?

Kansas

The North American spec LS400 had two electric fans. I remember noticing the electric fans on the 90 LS I drove for many years operating maybe once - on a 100+ degree day while idling over an hour in a stadium parking lot. The temperature gauge never budged off normal.

The 95-up North American LS400 had one electric fan - same as the 90-94 LS400 sold in Europe.

matchesLS

Thanks for the correction. I obviously was assuming that the pre-95s were the same as mine. I'm still learning.

Atrofee

Thanks for everyone's help. I added full disclosure because this 90 LS400 is not mine and I was not given all the details until I looked at it and asked questions, Kind of like stump the magician. Here we go
The Clutch Fan is engaged.
I tested the 2 Front Electric Fans and they work.
NORMAL at cold start Temp gauge @ "C"; Hot @ 3:00 (O'Clock) mark
NOW Broke cold start Temp gauge @ first mark above "C"; Hot @ 2:30 (PM) mark
A MAJOR pothole was run over to cause this change. AC was serviced recently and tech informed owner of fans.

I found a RDI Relay labeled RDIFAN in Relay/Fuse compartment in Engine bay driver side.

This is apart from ones below headlight?

Thanks Again

matchesLS

So what is wrong with the car? Is it getting hot? Overheating?

Atrofee

Owner says its running hot. Hard to say. Overheat means stop. I dont believe that to be the case.
The Temp Gauge is skewed Possibly due to Pothole. What is trip temp of Elect Fans.
Kansas says: never budged off normal.Even in100+ idling.
Is Water jacket sensor the one that triggers Elect Aux fans ? Can I assume that the 30 AMP RDI in top of bay supports the 2 RDIs under the headlight?

How do I thank people that respond to help (apart from cash).
Thanks you ALL

matchesLS

If the gauge is off I would look to replace the temperature sending unit first. If the clutch fan is working properly and all other cooling systems are good, you shouldn't have a running hot issue. On my car the outside temp has to be over 100 with the A/C on and slow driving to turn on the electric fan. And my needle is steady in the middle of the gauge at normal operating temp.

matchesLS

And just a simple thanks is enough.

Atrofee

Under closer examination the left electric fan has a dead or rough spot that causes the RDIFAN to Blow. Now fans behave properly but the gauge still appears skewed.
Thanks matchesLS and kansas for your help