It's a pretty common problem. The heater core is not a long series tube with flow throughout. There's an inlet on top, outlet on bottom and multiple parallel vertical tubes. The ones closes to the inlet & outlet have the highest pressure and highest heat, so they remain somewhat clear. The tubes furthest away have lower pressure and are cooler, and tend to pack with crud more easily. Eventually, the whole thing will likely sludge up if you don't clean out the system.

 

I have 2006 Seinna AWD and also facing same problem recently after i put so Barr's Liquid Copper in the coolant to fix the small leak on the bottom of the radiator. Well Radiator is not fix but my passenger side heat is GONE. What a FIX right.

So well I took it to 4 different mechanic and they all checked the Acctuator there are three in 2006 Sienna and they all are working. Heater core inlet and outlet hose are also warm/Hot and mechanic are confuse how in the world only one side of heater core is not working.

They all seems to agree that the LIQUID COOPER COULD HAVE CLOGGED ONE SIDE OF THE HEATER CORE.DOES ANY HAVE HAVE EXPERIENCE WITH CLOGGED HEATER AND YOU STILL GET GOOD HEAT FROM DRIVER SIDE BUT NOT PASSENGER.

i MEAN THERE IS ONLY ONE INLET AND ONE OUTLET SO IF HEATER CORE IS CLOGGED THEN HOW IS MY COOLANT CIRCULATING IF HEATER CORE IS CLOGGED ANY EXPLANATION.

I would like to get my heat problem fixed and appreciate the help.

ddpat,
Was wondering if you ever pinpointed the exact issue/cause, what it was, and most importantly how you fixed it. I have no doubt I have caused exact same issue you did with the Bar's Stop Leak . All of my servo motors are working flawlessly, and heat worked perfectly......but like you, I had a leaking radiator, poured in exact same Bar's product. It didn't stop leak....so I just had radiator replaced......but like you I now have no heat on R passenger side (ice cold) while driver side is hot. Again, checked passenger servo temp door actuator and working perfectly fine when adjusting temp. Problem started right after I put Bar's in. It is a Sienna Limited with rear zone. The rear also just started blowing cold when passenger did after the Bars stop leak always added. Mechanic who just replaced radiator has van now and said was going to try to reverse the lines on the core. He said sometimes reversing the flow can relieve the blockage.
Any help/ thoughts on what ultimately was done to unblock what the Bar's did is greatly appreciated. Or how you ultimately corrected blockage (assuming the Bars did clog core) and damage done. In hindsight, I should have just replaced radiator and never added the Bar's stop leak.
Thanks in advance

 

Reversing the heater core lines sometimes works. If it were my van I'd to flush out the cooling system with one of the chemical flushes.

 

Thank you very much for more potent chemical flush suggestion if reversing lines does not correct.

 

It's a pretty common problem. The heater core is not a long series tube with flow throughout. There's an inlet on top, outlet on bottom and multiple parallel vertical tubes. The ones closes to the inlet & outlet have the highest pressure and highest heat, so they remain somewhat clear. The tubes furthest away have lower pressure and are cooler, and tend to pack with crud more easily. Eventually, the whole thing will likely sludge up if you don't clean out the system.

It's a pretty common problem. The heater core is not a long series tube with flow throughout. There's an inlet on top, outlet on bottom and multiple parallel vertical tubes. The ones closes to the inlet & outlet have the highest pressure and highest heat, so they remain somewhat clear. The tubes furthest away have lower pressure and are cooler, and tend to pack with crud more easily. Eventually, the whole thing will likely sludge up if you don't clean out the system.

Hello:

Airline mechanic.
Pretty sharp on this stuff.
Question
Heat on the left , not on the right on the vents
CE model single zone 2004

What would you check?

Thanks
Jeff
Fixandfly

 

Heat on the left , not on the right on the vents
CE model single zone.

What would you check?

Thanks
Jeff
Fixandfly

Always check the coolant level first and urgently. You have to look under the pressure cap when the car is cold. You didn't list a year. Some Gen2 Siennas have the cap on the radiator, as is traditional. Some have it on the top coolant hose. If you're low on coolant, you need to add it BEFORE driving it or running it for any length of time, even if you don't see the gauge climbing. The air pocket can get to the temp sending unit, causing it to incorrectly read while your van is dramatically overheating. If you are low on coolant, you have a coolant leak. The next step would be to figure out where. It's usually a plastic bit of the cooling system, but, sometimes, it can leak around the water pump (3.5L/2GR/later Gen2) or from a hose or from the overflow tank or other places. In a worst-case scenario, it can leak internally into the engine or transmission, bringing about the end of life for your van. After you have good coolant and you're sure it's circulating properly, you the most likely thing is something messed up with a servo. The CE typically has the most basic system, which usually manifests with heat or no heat at all, rather than by side. However, there may be a failure mode that is less common but still possible to produce your symptoms.

 

As I described, a partially clogged heater core will do this. Sludge and calcium deposits favor the far right side to begin clogging the tubes first (the cooler side away from the inlet by the accelerator pedal. As they spread, they limit heat on the passenger side.

Second possibility is the airmix flap is two parts as the plenum is split for 'his and hers' temp control. On the CE/LE they are run with one servo. On the upper models the flap rod is split and controlled by two servos. On the CE/LE the airmix flap or coupler that allows both to open/close with only one servo can break, and only the door on left operates as it should.

Seen both happen.

 

So I ran a flush nothing came out. Should the outlet still be getting hot regardless of the actuators? The inlet is scolding hot and I know the passenger side actuator arm is moving because I can here the arm going up and down. But unsure about the driver side, but I was under the impression the return side should still be hot as well.

Edit:
Randomly I got a little heat but only on the driver side