Help me fix my weak front heat (2006 Land Cruiser) (1 Viewer)

[ArnieC]

UPDATE - ALL FIXED - See my last post.


Hi folks, Hoping you can help me fix my weak front heat in my 2006 Land Cruiser. Here is what I have done so far:

Symptoms I have:

• Weak front heat on feet, moderate front heat on vents, good front heat on defrost
• Roasting hot heat from rear heat under center console
• Front heat will improve briefly if HVAC fan is turned off for a few minutes then turned back on.
• Front heat will improve when running at highway speed/higher RPMs
• Front heat will improve if heater hose to rear heater core is clamped off with Vice Grip
• With heater lines disconnected between motor and rear heater core, coolant just sort of pisses out - its not Mt. Gushmore.

All of this points me to low coolant flow to the heater circuit or a blocked heater core in the dash

• Verified operating temp with scan tool, got 190F or so.
• Checked temp of upper radiator hose (hot) and lower radiator hose (cold)
• Flushed system with Prestone flush, back flushed heater core several times.
• Refilled system with fresh Zerex Asian coolant.
• Validated all motors/servos work.
• Checked the little sensor/hose dealy under the dash.
• Cleaned the little sensor under the dash.
• Filled and bled system several times
• Radiator cap is good, holds pressure
• Vehicle does not overheat
• Coolant level is steady and maintains properly in reservoir
• Vehicle never overheats, warms up properly, needle runs slightly below half way up.

Things I am going to try next:

• Replace thermostat with Toyota OEM installed with jiggle valve in correct position. Not sure what thermostat is in vehicle now.
• Rod out/try to clean out the lines on the engine that feed the heater cores
• Block off lines to rear heater core for winter
• Try to flush the main heater core again with a more aggressive flush chemical
• Cry. I don't want to pull the dash.
• Sell it and buy a 200 series. Also don't really want to do that.

I found some evidence of some RTV around some of the water pump connections, I know the vehicle had its timing belt done by an indy shop before I got it.
Hoping it may be blocked up? Any suggestions? I searched and found a few threads on the subject but they never posted a conclusion.

 

[morganism]

Does that model have a heater blower resistor? Causes pain on the older models.

Disconnect rear heater hoses first, so you don't just blow all the crap into it.

Could the heater hose T grommet have come out, and are plugging the lines?

Here are my original heater T's....

 

[Trunk Monkey]

Simple one some have reported, the carpet has scootched up over the floor vents. Push it back down, voila.

 

[ArnieC]

Not the carpet, thats clear. Get plenty of cold air out of the foot vents!
Blower motor runs fine, it is new as the old one was noisy and the A/C will freeze you right out.

This is definitely a heater core coolant flow issue, just wondering where I should look before I pull the dash to replace the core.

 

[LC CT]

This is interesting, I have noticed weak heat at the feet recently as it’s been cold out. Following this to see if you get any resolution, I hope to god it’s not the heater core.

 

[ArnieC]

My buddy loaned me his Air Lift system to evac and fill the coolant, gonna do that along with some CLR in the main heater core for a few hours and a new OEM thermostat from Toyota-san this weekend. Will report back.

I am very certain it is a coolant thru the heater core flow issue, drove this morning with the heat off to operating temp, turned on the heater, got hot air for about 30 seconds from the foot vents, and it dropped pretty quickly to warm air.

The big question is what is causing it.

 

[Ninja Cruiser100]

The heater core is not that big a deal just backflush it. My heat didn’t work at all, flushed the core and it blows like a volcano now.

 

[ArnieC]

I have backflushed it with a garden hose and done a chemical flush - slight improvement but no love.

 

[LC CT]

The heater core is not that big a deal just backflush it. My heat didn’t work at all, flushed the core and it blows like a volcano now.

I’m not too familiar with this procedure, are there any write ups or info on how to do this correctly? Thanks

 

[Captndcoke]

Similar issue, heat works in the front but it blows cold air in the rear. Any guesses?

 

[2001LC]

Temp gauge (they vary a bit) will sit right at 90 degree, not a little below. Air in system (which thermostat jig valve must be at top to bleed air), will give low temp on gauge and heat will blow cool. Weak thermostat it will run cool, but you IR gun 190 F indicates okay.

Number one reason for low or no heat, is coolant "low" or "air bubble" in heater core. When bleeding coolant system it's very important to check under cap of radiator after bring to full operating temp, then allow to cool down for 8 hours.

I once had air bubble that driving and slamming on brakes finally released from heater core.

When flushing front heater core, it should flow unrestricted.

 

[2001LC]

BTW: Using tap water to flush is bad idea.

Prestone sell a tee that splices into heater hose and attaches to garden hose, it promotes use of tap water. For this reason I do not trust Prestone products.

 

[ArnieC]

BTW: Using tap water to flush is bad idea.

Prestone sell a tee that splices into heater hose and attaches to garden hose, it promotes use of tap water. For this reason I do not trust Prestone products.

Yeah those tap things are not great, wouldn't use one of those. 6 hrs of driving with tap water in the cooling system shouldnt hurt anything, and its easy to back flush off a garden hose and not off some sort of rigged up pressure vessel with distilled water in it.

I ordered a new thermostat and O-ring from Toyota-san today, should have it by the weekend, will update this thread then.

If anyone has suggestions where to look for low coolant flow to the heater cores, I am all ears.

 

[nissanh]

Mine had the same issue. Rear is hot and front is warm. Flushed several ways with water and got some residue. We have lots of dissolved calciumcarbonates and those have settled in the core. I used 9% vinegar and soaked the core for days with a flush a day. It imprpved a lot and i am getting 56 Celsius (about 130 Fahrenheit) now. If you live in an area where there are dissolved minerals then that could be the cause. CLR should work, but I kept it as my last resort. Vinegar did the trick to me. I also have a post about it.

 

[nissanh]

You can burp the system by keeping the radiator cap off DO THIS ONLY WHEN THE ENGINE IS COLD +WEAR GOGGLES, and starting the engine to warm up. Keep the ac and heater both on to heat the engine quicker and to flow coolant through the heater core. If these is an air bubble, the coolant level will go down, then add more coolant mixture. I use this method and never had an issue on all my vehicles.

 

[2001LC]

*** 6 hrs of driving with tap water in the cooling system shouldnt hurt anything, ****.

Problem is, when tap water is used/added no way to get it all out.

 

[dwh13]

I’m not too familiar with this procedure, are there any write ups or info on how to do this correctly? Thanks

I followed the instructions in this video and it worked like a charm! Went from 75 degree temps measured at the vent to 140+!

Flushing the heater core. It was putting out maybe 80 degree air on full max.

• dwh13
• Oct 16, 2018

I KNOW, y'all are having a spasm at hooking up a garden hose to the cooling system, but it was...

Refilling the heater core with coolant

• dwh13
• Oct 16, 2018

Heater core flush worked like a dream! Removing that little bit of sediment almost doubled my vent temps!

• dwh13
• Oct 16, 2018

 

[Ninja Cruiser100]

There you go! Boom!

 

[Spike555]

There is not enough water left in the system after draining to say so. Maybe a cup in the whole system.
Flushing with a garden hose is fine, if you want to get every last drop out, jack up the back of the truck. Everything will run forward adn drain.

You can fill the system with water form the garden hose, add your cleaner, drive for a day or so and then drain and flush the cleaner out and you're good.

 

[2001LC]

A properly maintained coolant systems will never become clogged. Adding tap water is number one reason they clog.

There are ways to remove ~90 of fluid from our cooling system, jacking up rear is not one of them.