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Discussion Starter · #1 ·
Hey guys,
I am trying to help my girlfriend with her 2007 TC, automatic transmission. A couple weeks ago her heater stoppped working. Here is what I have done:
1. I have bleed the coolant system multiple times following different procedures, 1 of those procedures being from a Toyota manual.
2. Flushed the coolant from the radiator and the engine block. Obviously refilled with brand new coolant
3. Checked the fuses under the hood that were labeled HTR (this is a 40Amp big fuse). Also checked the ECS fuse
4. Randomly checked the fuses under the instrument cluster. I didn't see anything directly related to the heater or the climate control.

I have seaerched Google and various Scion forums to see what people suggest.

Many people suggest changing the thermostat, BUT the car does not overheat and when i check the hoses under the hood, the hose after the engine is warm and water is in it. So i dont think it is the thermostat.

On the driver side, near the center console there are two Silver colored pipes that come through the firewall. I felt both of these with my hand and one of them gets VERY hot when the engine is hot and the other is warm but not as hot is the first one i touched.

When the climate control fan is turned on, it blows fine. As you adjust the speeds is adjust speeds at the touch of a button. The air never gets HOT and the Defroster obviously never gets hot.

What else could be wrong? I would like to thank you in advance for your help.
 

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Discussion Starter · #3 ·
I think it's the thermostat.
What would make you think it's the thermostat? If the car isn't over heating wouldn't that indicate that the cooling system (Including the thermostat) is working properly?

Also, would the hot car flowing into those two Silver color pipes on the driver side indicate that hot water is flowing properly through the cooling system indicating the thermostat is working?

Even going beyond that. Wouldn't the upper radiator hose getting hot indicate the thermostat is working properly allowing hot water to flow through the entire cooling system?
 

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What would make you think it's the thermostat? If the car isn't over heating wouldn't that indicate that the cooling system (Including the thermostat) is working properly?

Also, would the hot car flowing into those two Silver color pipes on the driver side indicate that hot water is flowing properly through the cooling system indicating the thermostat is working?

Even going beyond that. Wouldn't the upper radiator hose getting hot indicate the thermostat is working properly allowing hot water to flow through the entire cooling system?

Where do you live?
 

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If the thermostat is bad it could be stuck open and just allowing coolant to flow all the time and never properly heat up. When you bled to coolant did you open up the bleeder on the top right of the radiator? If you increase the rpm to get the coolant warmer you should be able to get warm air in the cabin as well. Just to let you know I work at a Toyota dealership and have been there several years. I don't know of any issues except the heater core being plugged.
 

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Discussion Starter · #6 ·
Where do you live?
Los Angeles, CA

If the thermostat is bad it could be stuck open and just allowing coolant to flow all the time and never properly heat up. When you bled to coolant did you open up the bleeder on the top right of the radiator? If you increase the rpm to get the coolant warmer you should be able to get warm air in the cabin as well. Just to let you know I work at a Toyota dealership and have been there several years. I don't know of any issues except the heater core being plugged.
I guess I will check the thermostat but, I have searched this forum in addition to other Scion forums and have seen many people suggest the thermostat and the poster with the problem always says that changing the thermostat didn't solve the problem.

Here is the procedure i followed to bleed the air out of the coolant system: http://tijil.org/Scion_Docs/05_tC_S...air Manual/Cooling/Engine Coolant/x040001.pdf

I followed this procedure with the tube on the bleeder and without the tube. I tried it with the tube sticking in the air high above the edge of the hood. I tried it with the tubing hanging down on the floor in a bucket of coolant with coolant in the entire tube.

I also watched this video to make sure I wasn't crazy and that I was doing this properly:

If you read my original post in careful detail you will see that I state that the coolant temperature definitely gets hot while I am reving the engine to 2k-2.5k rpm.

I wish there was a way to pressurize the coolant system with air after it is drained. I would like to try and blow air through one end of the cooling system and see if it blows out the other end. This would ensure that nothing is plugging the heater core. Because the heater core hoses are a smaller diameter than the radiator hoses there is a possibility that something is blocking the raditor core. I did drain the coolant system but I would guess that there is the possibility of something blocking the heater core.
 

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Discussion Starter · #7 ·
If the thermostat is bad it could be stuck open and just allowing coolant to flow all the time and never properly heat up. When you bled to coolant did you open up the bleeder on the top right of the radiator? If you increase the rpm to get the coolant warmer you should be able to get warm air in the cabin as well. Just to let you know I work at a Toyota dealership and have been there several years. I don't know of any issues except the heater core being plugged.
What more can I do to try and flush the cooling system. I wonder if there is something stuck in the heater core???
 

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Sounds like you have a clogged heater core. You can verify it and possible back flush the heater core .
Also you might as well replace the thermostat too since on average thermostat last about 10 years. And if the thermostat gets stuck it will overheat the car and more likely cause a blown headgasket so replacing a thermostat is a good prevented measure. Anyway please check this video out on diagnosing a heat core issue from A1 Auto.

Here's a video that's bit more detailed.

Here's a chrisfix one:

Here's a EricTheCarGuy

And South Main Auto

Also a good coolant flushing video from Faye Hadley

And a good decent coolant vacuum refiller tool
 
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