Ls400 Mk3 Fan Blowing Warm

Smokybenchod · October 11, 2015

Hi all,

I recently purchased an LS400 mk 3 98 model and I'm really pleased with it - so refined and a pleasure to drive.

I have noticed that to get hot air out of the fan I have to put the setting up to over 28 degrees. Doing some research in this forum and the U.S. owners club forum, I am planning to replace the rad cap, thermostat and do a coolant flush using the procedure described in lexls.com. Does this sound like the correct plan of initial attack, as I'm figuring these things will probably need doing at some point anyway and aren't very expensive items?

Smokybenchod · October 11, 2015

Sorry to clarify I should have stated, to get the fan to blow *hot* I have to put it over 28 degrees. Below this setting it blows luke warm at best. Thanks.

Tulpen · October 11, 2015

Do you have the AIRCON selected ON or OFF?

Try both selections and see if it makes any difference. With it OFF it should give you heat with no problems.

Smokybenchod · October 11, 2015

Hi there, I'm away on business so can't check if it makes any difference if the air con is ON. I know for certain the issue I'm getting is when the air con is set to OFF as I seldom use the air con. Is this a bigger problem then - is my initial plan still a good idea?

Tinonline · October 11, 2015

I would check the temp gauge and how that behaves...is engine over cooled or is needle about half way or thereabouts? May be as electrical ie sensor fault. However your proposed work won't cost a fortune. Better to do yourself. I wouldn't flush just yet. Maybe temp sensor first. If engine is over cooled then thermostat first.

Smokybenchod · October 11, 2015

I would check the temp gauge and how that behaves...is engine over cooled or is needle about half way or thereabouts? May be as electrical ie sensor fault. However your proposed work won't cost a fortune. Better to do yourself. I wouldn't flush just yet. Maybe temp sensor first. If engine is over cooled then thermostat first.

Thanks for the advice, the needle on the temp gauge is pretty much about half way i.e. normal. So you think change the temperature sensor, is that an easy job, whereabouts is that? OK i well leave flushing for now - the main reason I suggested that is that I researched that air in the system can cause the fan not to blow hot and flushing and refilling can correct this.

Redsteve · October 11, 2015

Hello Smoky (always wanted to use that classic sound bite from Smokey and the Bandit),

check the fluid levels in the rad and expansion tank are OK as a low level will result in little or no heat coming out of the vents.

Steve.

Titch LS · October 11, 2015

Yes, check the coolant level first of all. If you do drain the system at any time, there is a old fashioned screw-type drain plug on the bottom of the radiator. Saves having to fiddle taking off the bottom hose as on other cars. Also, when replenishing the coolant, use Toyota long- life Pink coolant (which comes already mixed 50/50) or, Toyota Red which you will have to mix yourself 50/50 with distilled water. They are compatible. Refill via the hex plug at the top front of the engine. When nearly full, finish topping off at the plastic coolant reservoir. Filling it the proper way saves loads of time trying to 'burp' the system of air. It could be that you have an air lock in the system which is causing your current low heat problem.

plexus914 · October 12, 2015

Sounds like there is dirt in front of the car's heater core. Checked your cabin filter yet?

Smokybenchod · October 12, 2015

Sounds like there is dirt in front of the car's heater core. Checked your cabin filter yet?

Hi yep already changed this - it was filthy but it has a brand new one installed now :)

Spacewagon52 · October 12, 2015

Found this on the forum - it might help.

http://www.lexusownersclub.co.uk/forum/topic/35806-engine-coolant-changed-on-99-ls400/

Smokybenchod · October 12, 2015

Found this on the forum - it might help.

http://www.lexusownersclub.co.uk/forum/topic/35806-engine-coolant-changed-on-99-ls400/

Thanks for this, looks like everyone is in agreement that a coolant check / refresh is the first thing to do. Will give this a go and let you know if it solves the problem. Cheers all.

Tinonline · October 13, 2015

I would check the temp gauge and how that behaves...is engine over cooled or is needle about half way or thereabouts? May be as electrical ie sensor fault. However your proposed work won't cost a fortune. Better to do yourself. I wouldn't flush just yet. Maybe temp sensor first. If engine is over cooled then thermostat first.

Thanks for the advice, the needle on the temp gauge is pretty much about half way i.e. normal. So you think change the temperature sensor, is that an easy job, whereabouts is that? OK i well leave flushing for now - the main reason I suggested that is that I researched that air in the system can cause the fan not to blow hot and flushing and refilling can correct this.

So the cooling is working fine. I doubt you would have air locks. But if the coolant is old it is worth doing. I'm not sure where the senors are but someone will know! There will be one outside measuring climactic temp and one for the cabin.

Now if the external sensor has gone that upsets the heating. Never heard of the internal one going - that should be in the dash area with a little plastic grill cover I think.

Temp adjustments can take a while...especially if you are fiddling! Overcooling is when it takes ages to warm up and the needle stays around the first mark, seldom getting to near middle or middle, that is usually a faulty thermostat.

Please give us all the gory detail and the results! Good luck!

Tinonline · October 13, 2015

Yes, check the coolant level first of all. If you do drain the system at any time, there is a old fashioned screw-type drain plug on the bottom of the radiator. Saves having to fiddle taking off the bottom hose as on other cars. Also, when replenishing the coolant, use Toyota long- life Pink coolant (which comes already mixed 50/50) or, Toyota Red which you will have to mix yourself 50/50 with distilled water. They are compatible. Refill via the hex plug at the top front of the engine. When nearly full, finish topping off at the plastic coolant reservoir. Filling it the proper way saves loads of time trying to 'burp' the system of air. It could be that you have an air lock in the system which is causing your current low heat problem.

Definately fill from the hex plug. Use a small funnel, grab a stool or chair and be prepared to trickle it in. After about 20 years you will notice the overflow bottle filling up. I got mine up over half full (18 years) before coming to the conclusion that the fill would never stop at the hex plug end so as deftly as possible with the level as high as poss at the hex plus screwed it back up. I torqued correctly.

Then I topped up a bit at the tank. Then ran the engine up. I squeezed all the big pipes a number of times not that that did much. But it felt nice all the same. I can't recall the level dropping but if it does it's very little. You will be delighted with the results. Check it regularly when stone cold - you might need to add a tad but after that it will be stable.

There are plenty of good quality anti-freezes available that are absolutely fine for the engine. If you can still get red then red is good but the latest long lifers are pink OAT antifreezes. I wouldn't go for the other colours - they have a shorter life span. Lexus use pink in all new cars.

harrylime · October 16, 2015

Did you get this resolved? I was out in mine today and suddenly started to get cool air through the vents rather than warm. I had to turn the temp to the late 20s to get warm air through. The force of the air vents also seemed to increase at the same time

Smokybenchod · October 19, 2015

Did you get this resolved? I was out in mine today and suddenly started to get cool air through the vents rather than warm. I had to turn the temp to the late 20s to get warm air through. The force of the air vents also seemed to increase at the same time

Sorry for the delay in replying guys, still away on business! I have managed to call the Lexus dealer though and order 11 liters of the pre-mixed red Toyota Long Life Coolant as advised in the user guide. It's probably going to be a couple of weeks until i get round to this - and will probably get my local Indy to do it as I'm super busy with work at the mo. Will let you know how I get on. Cheers again.

Smokybenchod · October 30, 2015

Update:

Finally got round to changing the coolant as per the forum guide. Got my Indy to do it and he followed the instructions and charged me £28 labour! Top bloke he is. I've had to top it up a couple of time since so would recommended buying 12 litres in total to save a trip back to the stealer. The fan is now blowing hot again so thanks for all the expert advice, really appreciate it.

Next job: dual cat and middle pipe replacement, one for early next year once I've saved a few pennies!