Do Not Sell My Personal Information Jump to content


Electric Cooling Fan Running All The Time


Recommended Posts

The electric cooling fan on the front of the radiator of my 1991 LS400 is running all the time, even when the engine is started from stone cold. I expect it's a sender in the radiator thats stuck on.

Any ideas?

Link to comment
Share on other sites



is this a single electric fan on the front of the radiator ( not the viscose fan behind the radiator ) which is on all the time? it could be the viscous fan isn't working and the aircon fan is on to make up for its loss to prevent the engine from over heating, just a thought

Link to comment
Share on other sites

is this a single electric fan on the front of the radiator ( not the viscose fan behind the radiator ) which is on all the time? it could be the viscous fan isn't working and the aircon fan is on to make up for its loss to prevent the engine from over heating, just a thought

Yes it's the single electric fan on the offside of the radiator. It runs from stone cold. It even starts running before I start the engine in the morning when I turn the ignition on. The cooling system seems fine, other than this fan running all the time.

Link to comment
Share on other sites


its aircon related so unplug it but keep an eye on your temp gauge because it could be the viscous fan isn't working

The Viscous fan is working fine. And as I've said the electric fan runs even when the engine is stone cold.

Link to comment
Share on other sites

disconnect the aircon fan ( do you know how the viscous fan works? ) its relevant to this problem because the AC cuts in when it fails

Yes it will cut in when the engine gets too hot due to the viscous fan not working, but as I've said the electric fan runs all the time no matter what temp the engine is, and the viscous fan is working perfectly.

I suspect there is a temp sender unit on the rad which triggers the electric fan to run if the engine gets too hot. I suspect the temp sender on mine is stuck on so to speak, making the fan run all the time.

Link to comment
Share on other sites

With your symptons, check fan relay and temp.switch

Check the temp. switch wiring is still on , disconnecting the temp. switch causes the fan to run.

Or break in the wire from fan relay to temp switch........the fan relay is in the relay block behind the passenger headlight.

LAST CHECK AFTER ALL THESE, AIR CON HI-PRESSURE SWITCH BEHIND DRIVERS HEADLIGHT. :duh: :unsure:

Link to comment
Share on other sites

my 1990 ls400 got same symptom, 2 electronic fans in front of rad always run when i turn ignition on regardless of engine temp or air con on or off

in lexus service manual, there is a check procedure for control of these fans, but too busy now for that

Link to comment
Share on other sites

  • 2 weeks later...

Well I got round to having a look at this fan today. There is a connector in front of the radiator right in the middle of the rad. The wires coming out of the top half of this connector split into two runs and one runs up to part of the wiring loom under the slam panel and the other runs across and disappears under the offside headlight.

The bottom half of the connector splits with one half of the wires goes to the fan itself and the other half go to a block roughly 90x15x15mm which sits on the vertical brace that sits in front of the radiator. This block is held about 15mm away from the rad. I've guessing it's some form of thermocouple, but whether it's the cause of the problem I have no idea.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...




Forums


News


Membership