LX470 Heater Function Problem

[ItGoesTo11]

You're probably ok, these 100 are tanks and can take a licking and just keep on ticking.

I recall you said cabin heat felt hot. Very hot was the answer I was looking for, but it is subjective.
I've been out all day working on 100's, and don't recall what you may have said about coolant temperature gauge position over last 8 months?

The cabin heat is very hot now, yes...working normally.

The temp gauge was in it's normal position all through the issue over the last 8 months, it never varied and warmed up normally. That's why this was so maddening to diagnose.

 

[ogsuv]

This thread is closest to a situation I had recently also. I thought I would post to hopefully help someone out.

00 LC 244k. -13f with -30f wind chill in Wisconsin one day recently. Heater did not want to get warm. I drove about 4 miles before the temp got just to the tip of the red zone on the gauge. It is freezing out but I am overheating? I pulled over and hood frozen shut, but fluid pouring out of somewhere.

I am thinking the worst, but limp home after temp leveled off, park it in semi-heated parking garage for 3 days. Start it up and still no heat. reservoir shows coolant full but I know I lost some. I added about 3/4 gallon directly to radiator and all good for the last week or so.

I must have been low on fluid for awhile, a slow leak or air in the system and possibly the tstat froze during that time are my only thoughts. Was living in a apartment for 6 months so didn't have the benefit of the same spot to notice puddles, etc....

I had done the T's and hoses, but will do waterpump and tstat for peace of mind soon.

I will never trust the overflow reservoir again. I'll be checking the radiator more often for fluid level.

 

[LBridges]

This thread is closest to a situation I had recently also. I thought I would post to hopefully help someone out.

00 LC 244k. -13f with -30f wind chill in Wisconsin one day recently. Heater did not want to get warm. I drove about 4 miles before the temp got just to the tip of the red zone on the gauge. It is freezing out but I am overheating? I pulled over and hood frozen shut, but fluid pouring out of somewhere.

I am thinking the worst, but limp home after temp leveled off, park it in semi-heated parking garage for 3 days. Start it up and still no heat. reservoir shows coolant full but I know I lost some. I added about 3/4 gallon directly to radiator and all good for the last week or so.

I must have been low on fluid for awhile, a slow leak or air in the system and possibly the tstat froze during that time are my only thoughts. Was living in a apartment for 6 months so didn't have the benefit of the same spot to notice puddles, etc....

I had done the T's and hoses, but will do waterpump and tstat for peace of mind soon.

I will never trust the overflow reservoir again. I'll be checking the radiator more often for fluid level.

Bringing an old thread back to life. Not exactly the same as others described but pretty close.

Yesterday was pulling into work and noticed my temp gauge was near max. As it was dark didn't want to sit and idle so I shut it down and with a flashlight looked for a leak point. No fluid coming out underneath and no sweet smell in the engine compartment. I had done a DIY water pump/timing belt/heater T's job some months ago, but never had occasion to run the heater (being in Florida and the 100 isn't my DD). Note: I used some low pressure air to blow out old coolant from the heater cores when I did the pump and belt, and to be honest I didn't think about a bubble in the system. Although as a former Toyota MR2 owner I should have.

After the sun came up, went out to check, found nothing on the ground and no sign of pink stains around the pump, T's etc. Opened the radiator and water was below fins but the remote reservoir was at the normal height. Turned on engine, set front and back heaters to max and got about 3/4 gallon of water into the system. Being at work not enough time then to get it fully up to temp, but gauge moved about half way between cold and normal. When the day ended I did head for home but not thinking very well I also didn't run the heater as a test (day had warmed up to 77F).

Going to check rad level this morning. The ride home involved a lot more traffic and the outside air was over 15 degrees warmer so I assumed any overheating would be worse (carried a couple of gallon water jugs in case). Gauge went up to normal level and was rock steady all the way home

Did not replace radiator cap when I did the TB and water pump, but it was holding some pressure because there was a bit of a pop when I opened the cap at work (about an hour after turning the engine off). I almost wish it would overheat again so I could figure out what is wrong. Without input from the collective mind here, and no further issues pop up, I'm going to assume I had some sort of heater bubble.

 

[2001LC]

Sounds like you had and air bubble. Normally your reservoir would be at the low line after an 8 hour cool down of engine. Once engine warms up reservoir should be at or near the hot line.

Recheck both the radiator & reservoir each morning after cool down. Top off radiator and bring reservoir to cold line. Recheck reservoir when engine hot (at operating temp) to see if near hot line.

If you find the reservoir at cold line, but radiator is low after doing above procedure 3 times, replace radiator cap with OEM.

Only use distilled water in your coolant system and mix with Toyota Red LL 100%, to get a 50/50 mix in your 2000 LX470. If you've switched to Toyota SLL pink, which only comes in 50/50 premix, use that not D water. It's important for your coolant system to be a 50/50 mix.

Note: Keep in mind the ambient temperature will change your cold test level. Example here in Colorado if it -10f ambient temp., the reservoir will be lower, and higher if ambient temp 75f. Even 10 degree will make a some difference in expansion of fluid.

 

[ogsuv]

I haven't had any trouble since my post around Christmas. I probably have put on 2500 miles in various conditions since then.

 

[ItGoesTo11]

F

I haven't had any trouble since my post around Christmas. I probably have put on 2500 miles in various conditions since then.

FYI, with my situation, (leaky T's), the reservoir showed full because once you have a leak in the system, the radiator can't draw coolant back into it because it draws in air from the leak instead, nullifying the "drawing" effect from the reservoir tank. If the system isn't sealed, the reservoir level is a useless indicator of coolant level.

So, I always check the radiator level from time to time now.

 

[ctownhartford]

wow....iam gonna check my radiator too...my expansion tank has coolant.!...my 2005 lx doesnt blow heat effectively.

 

[ctownhartford]

update...just checked..radiator is full !... any idea why heat is working at say 20% efficiency? at 85 F setting too.

 

[2001LC]

Check your coolant engine at operating temp. Weak thermostat or wrong mixture of coolant and engine coolant can run cool. Ideal is 184 to 187F around town.

Also try setting all the way hot, not just 85F. If cabin sensor hose off, sensor dirty or weak. You may find it works when set to hot, but not 85 F setting.

Note: Always check radiator after parked with front end higher than rear, and after a full 8 hour cool down.

 

[ItGoesTo11]

Have you changed your heater core "Tees"? My issue was they were leaking slowly, slow enough not to drip on the ground, but enough to cause air in the system and stop the coolant flowing past the highest point (the "Tees", actually) and into the heater core.

Even with the Tees leaking, the expansion tank will show full, and the radiator will start to show lower levels over time, but it doesn't take much air to bubble to the top of the system (the "Tee" area) and keep coolant from flowing past them into the heater core.

Look earlier in this thread for a photograph of the location and what they are, basically a three way plastic Tee on the left side of the engine near the firewall. They are made of plastic and eventually begin to crumble from the heating cycles. You can order them new from Toyota/Lexus and they should last another 150k miles.

 

[shtbrwn86]

Sorry to revive an old thread again, but members who are commenting on this one seem to know what they are talking about. My 99 LX blows lukewarm air when set to HOT. Also, when I set the mode to blow at the front vents only, I can hear the fan running loudly but it only sort of blows air out. When I switch it to COLD you can hear slow down, then speed back up and the air that comes out is very strong. Way stronger than the air flow from the HOT setting. This is on Manual, NOT AUTO.

But the temperature is what has got me scratching my head. When I bought it last week, in Phoenix (110 OAT) the coolant reservoir was at the LOW mark at operating temperature. So I topped off the reservoir and went on my way. When it cooled down it drew down the reservoir significantly. When it heats up at again, the reservoir fills up, so I think that part is working right.

Today, I tried to bleed the system by parking on an incline, running the heater on high, and with one of those no-leak funnels, I ran the engine for about 25 minutes, revving it off and on. I noticed that sitting in my driveway, the temperature coming out of the vents was 142 degrees. VERY HOT! I was pretty excited. I thought I got the air out and was good to go.

Well about 4 hours later I go take it for a victory lap and the damn heater is now back to blowing luke-warm. Thoughts? Every time I check my coolant in the radiator it seems to be full. And the reservoir is doing something, as the level is always higher after driving for a while than when I first start it up in the morning.

I rented a coolant pressure tester. I have a theory that there is a leak somewhere and I was temporarily able to overcome it and get heat, but as the system cooled down it sucked air in through the leak? I suspect the leak is in the heater core, yet I see no indications of leaking in the cabin.

 

[2001LC]

Check coolant level by just looking under radiator cap and top all the way up. Do this in the morning after 8 hour cool down. Keep checking each morning after cool down, until no coolant is needed. During your warm up to operating (op) temp and while at op temp, have both front and rear heat on hot. Watch engine temperature through tech stream, not dash water temp gauge. You should see ~187F at op temp. As you drive around at operating temp (for at least 20 minutes) it should fluctuate ~184 to ~190F.

Make sure hose in reservoir is going straight to bottom of tank. They sometimes get hung up on shelve in reservoir tank, which we do not want to happen.

Base line coolant system:
Clean radiator fins of grasses, cotton, bugs, etc..
Drain coolant at radiator and both block drains.
Replace heater TEE's. I use OEM tees & factory clamps (old or new).
Replace hose(s) swollen as needed. Swollen hoses can be indication of overheated..
Flush by filling with 100% distilled water, bring to operating temp and draining multiple times unit runs clear.
Replace thermostat & gasket with OEM.
Replace radiator cap with OEM.
Use Toyota LL (Red) and distilled water mixed 50/50.
Burp air from system daily, until no more 50/50 mix can be added.
Set reservoir level, after 8 hour cool down. To near full line, if OAT at or near average daily high. At low line, if OAT below average daily low OAT.

Clean Cabin HVAC sensor. MAF sensor cleaner works best..

Scored 2006 LC w/194K AHC (untouched Jewell restoration)

I finished cleaning the paint with my porter-cable DA buffer using a 5" micro fiber medium cut pad with cutting compound. I had to adjust my timing to catch early mornings while the ambient temperature was cool. Much above 72 deg and the cutting compound just worked me to death. The paint looks...

forum.ih8mud.com

 

[ItGoesTo11]

This issue seems similar to what I experienced when my "heater tees" began to leak. The Tees are at the highest point in the cooling system and will trap air in that area, this is just before the heater core and the water pump at idle doesn't have enough pressure to push the coolant "up and over" the area with trapped air. These tees are made of plastic and will eventually fail, it's just a matter of when.

When you bled/topped off the reservoir, you put enough coolant in the system for the water pump to push up and over the area with trapped air, but it eventually leaks out again, very slowly onto a hot transmission and evaporates, so you usually cant spot a leak on the floor. Replace the Tees, that should solve your problem, I'd suggest just going to the dealer to buy new ones, they aren't expensive and they'll slip right in, they are usually good for 150k miles or more...

They are located behind the drivers side rear area of the engine, up high where you can see them easily. They might have some crusty looking material around them, that's the evaporated coolant. If they haven't been replaced they need to be anyway.

 

[shtbrwn86]

Check coolant level by just looking under radiator cap and top all the way up. Do this in the morning after 8 hour cool down. Keep checking each morning after cool down, until no coolant is needed. During your warm up to operating (op) temp and while at op temp, have both front and rear heat on hot. Watch engine temperature through tech stream, not dash water temp gauge. You should see ~187F at op temp. As you drive around at operating temp (for at least 20 minutes) it should fluctuate ~184 to ~190F.

Make sure hose in reservoir is going straight to bottom of tank. They sometimes get hung up on shelve in reservoir tank, which we do not want to happen.

Base line coolant system:
Clean radiator fins of grasses, cotton, bugs, etc..
Drain coolant at radiator and both block drains.
Replace heater TEE's. I use OEM tees & factory clamps (old or new).
Replace hose(s) swollen as needed. Swollen hoses can be indication of overheated..
Flush by filling with 100% distilled water, bring to operating temp and draining multiple times unit runs clear.
Replace thermostat & gasket with OEM.
Replace radiator cap with OEM.
Use Toyota LL (Red) and distilled water mixed 50/50.
Burp air from system daily, until no more 50/50 mix can be added.
Set reservoir level, after 8 hour cool down. To near full line, if OAT at or near average daily high. At low line, if OAT below average daily low OAT.

Clean Cabin HVAC sensor. MAF sensor cleaner works best..

Scored 2006 LC w/194K AHC (untouched Jewell restoration)

I finished cleaning the paint with my porter-cable DA buffer using a 5" micro fiber medium cut pad with cutting compound. I had to adjust my timing to catch early mornings while the ambient temperature was cool. Much above 72 deg and the cutting compound just worked me to death. The paint looks...

forum.ih8mud.com

I appreciate your reply. I did check my coolant level this morning after cool down (after running it with the funnel until it got really hot the day before) and there was maybe an oz or two needed to fill it up to within an inch of the very top. Not much. I will try again tomorrow morning. I don't have TechStream but I have one of those bluetooth OBD2 adapters and using TorquePro I see 185 most of the time, with it periodically getting as high as 192 and then settling back down. Now I have only tested this in Seattle area where OAT is 60ish right now.

Took a quick look from underneath and there is a little bit of grass/debris on the fins but it's probably 90% clean.

Ordered new heater hoses/Tees and upper and lower radiator hoses. I cleaned off some of the leaking coolant on the upper hose and notice new little coolant bubbles appearing where it connects to the engine.

I also ordered a new thermostat and once the hoses come in I am going to replace all of them, then do the coolant flush you mentioned.

 

[shtbrwn86]

This issue seems similar to what I experienced when my "heater tees" began to leak. The Tees are at the highest point in the cooling system and will trap air in that area, this is just before the heater core and the water pump at idle doesn't have enough pressure to push the coolant "up and over" the area with trapped air. These tees are made of plastic and will eventually fail, it's just a matter of when.

When you bled/topped off the reservoir, you put enough coolant in the system for the water pump to push up and over the area with trapped air, but it eventually leaks out again, very slowly onto a hot transmission and evaporates, so you usually cant spot a leak on the floor. Replace the Tees, that should solve your problem, I'd suggest just going to the dealer to buy new ones, they aren't expensive and they'll slip right in, they are usually good for 150k miles or more...

They are located behind the drivers side rear area of the engine, up high where you can see them easily. They might have some crusty looking material around them, that's the evaporated coolant. If they haven't been replaced they need to be anyway.

View attachment 2357170

When I bought the LX I saw that one of the dealer attempts to fix the heater involved back-flushing the heater core and also replacing the heater Tees. The look better than yours and I have 245k, so i think they probably did? That was done about 40,000 miles ago, but it was also like 6-7 years ago and the car was in Phoenix where it gets really hot. I ordered new Tees and hoses as well as new upper/lower radiator hoses and thermostat. I live in the Pacific NW and won't be putting a ton of miles on this so I think the new hoses/tees are cheap insurance.

One thing i wanted to touch on though, is that you initially noticed an issue with your auto climate control blowing cold air right away? Well i just went and tested mine and if i set it to auto HOT the fan initially doesn't kick on, but as the temp increases the fan speed increases. If that's the case then it's detecting hot coolant in the core I would assume?

 

[2001LC]

Make sure to check the cabin HVAC sensor!

 

[ItGoesTo11]

When I bought the LX I saw that one of the dealer attempts to fix the heater involved back-flushing the heater core and also replacing the heater Tees. The look better than yours and I have 245k, so i think they probably did? That was done about 40,000 miles ago, but it was also like 6-7 years ago and the car was in Phoenix where it gets really hot. I ordered new Tees and hoses as well as new upper/lower radiator hoses and thermostat. I live in the Pacific NW and won't be putting a ton of miles on this so I think the new hoses/tees are cheap insurance.

One thing i wanted to touch on though, is that you initially noticed an issue with your auto climate control blowing cold air right away? Well i just went and tested mine and if i set it to auto HOT the fan initially doesn't kick on, but as the temp increases the fan speed increases. If that's the case then it's detecting hot coolant in the core I would assume?

Correct, the system detects the temp of the engine coolant and manages the blower fan accordingly. There are TWO temp sensors on the engine, one for the temp gauge in the dashboard and one for the coolant temp measurement for the heater/ECU. It doesn't detect it in the core, but rather in the engine, but it accomplishes the same thing as far as determine when and hot much fan speed to apply. Your fan appears to be working correctly.

It is possible the heater fan can start at full speed and blow cold air, if there is air in the system and the coolant is low enough, the ECU temp sensor heats up too quickly and fools the ECU into thinking the engine is warmer than it is. (since there is no cold coolant flowing past it, the air surrounding the probe heats up fast)

 

[shtbrwn86]

Well I think I found my problem...well I think it's a start at least. Went out to check coolant and reservoir was EMPTY (engine was cold). Check radiator and it took almost about 15 oz to top off.

I pulled the skid guard underneath, put a pressure tester on it and it won't hold pressure. Starts dripping right away. Looks like it's coming from the shroud/radiator? I also pressure tested the radiator cap because the records showed the dealer recommended it but the prior owner didn't replace it? But he DID replace the radiator. Well the cap didn't release when it was supposed to. Actually it never released? Maybe I did something wrong testing the cap, but I did order a new cap.

I'm wondering if all the issues the guy had with the radiator and hoses and water pump and thermostat etc were due to a bad cap that wasn't releasing pressure? Maybe that messed up the radiator and caused a leak?

If so thats kind of annoying because one of the reasons I bought it was because it showed the guy went to the dealer for all this coolant system work and it might need a new radiator already?

At any rate I'm assuming that could be a part of why my heat isn't working properly? Although the rear core still blows pretty hot.......

 

[2001LC]

Very offended I find that Dealerships or corner shop have not burped properly, and not replaced cap and thermostat with new radiator. I'll bet the instruction for your special funnel, states something to the effect of: Check for air in the system. Those funnels can and do leave air pockets.

Often times while adding coolant, I spill some. It will drip down in area yours is dripping wet.

I'd wash radiator and area of all coolant signs, and keep top each morning unit day after it will not take anymore in radiator. Then, keep watching for leak(s). Most leaks are from top plastic near where it meets metal, on old radiator. Once in a while from object petrating the radiator.

"Pinky crusty" The upper radiator hose shows signs of leak at hose gooseneck of water bypass joint front. I also see impression of OEM hose clamp, but no clamp.

You can see the bracket for the transmission cooler line is broken. It's important to have secured. The cooler line bouncing around, which will loosen the connection. I tie those up, until I get a new bracket in and on.

 

[ItGoesTo11]

Air in the system will get trapped at the "Tees" and cause the same condition as a leaking Tee, as it's the highest point in the system.

LX radiators also are prone to leaking where the plastic top and bottom caps are "crimped" to the aluminum body. it might be a replacement radiator, but if it has more than 100k on the radiator that could be the culprit. And, while you are at it...replace those Tees if they've never been replaced.