05 Sienna...rear heat blows cold - Toyota Nation Forum : Toyota Car and Truck Forums
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#1 Old 03-18-2013, 07:31 PM
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05 Sienna...rear heat blows cold

Just bought an 05 Sienna...the rear heat only blows cold. Temp does not change any when the temp selector is turn to cold or hot. Any pointers on were to start with this? Coolant level is full.
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#2 Old 03-19-2013, 08:32 PM
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Are you ready to pull the interior rear panel to look at the rear heater? There is an electrically operated solenoid water valve that would be a good item to examine first. Plus an airmix shutter, IIRC. I can give you some pointers / diagrams if you are looking to tear into it.
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#3 Old 03-19-2013, 08:57 PM
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Re: 05 Sienna...rear heat blows cold

Yes definitely willing to tear into the panel back there. Just waiting on a somewhat warm day to do it. Any pointers or diagnostics steps would be great.

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#4 Old 03-20-2013, 07:50 PM
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Re: 05 Sienna...rear heat blows cold

Check the coolant level in the overflow tank, it should be between min amd full.

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#5 Old 03-21-2013, 10:15 AM
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not sure you did it or not, can you adjust the temp from the 2nd row overhead panel?
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#6 Old 03-21-2013, 05:19 PM
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Re: 05 Sienna...rear heat blows cold

No matter if the temp selector in the second row is on cold or hot it still blows cold. If the a/c is turned on it blows colder.

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#7 Old 03-21-2013, 09:33 PM
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I've got some stuff on the rear unit that I've collected, but need to get it organized and uploaded to my photo site for viewing. Pretty busy with work right now, so probably early next week?
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#8 Old 03-21-2013, 09:54 PM
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Re: 05 Sienna...rear heat blows cold

That'll work for me. No rush.
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#9 Old 12-30-2013, 09:31 PM
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Fibber2, did you ever upload the info? I just noticed that our '08 has no rear heat, either.

Regards,
Steve

'08 Sienna LE FWD
'13 Tacoma PreRunner SR5 Double Cab Long Bed Texas Edition 4x2
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#10 Old 12-31-2013, 04:26 PM
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Hey Steve. To begin with, make sure that a button on the rear control panel is properly depressed and that you have a mode light on (applies to LE manual system). My kids have occasionally pressed a button part way and that seems to actually disable the fan and sometimes the temp control.

Manual or automatic? Exactly what's it doing? Fan and mode works but no heat? Front working properly?
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#11 Old 01-01-2014, 02:24 PM
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Quote:
Originally Posted by Fibber2 View Post
Hey Steve. To begin with, make sure that a button on the rear control panel is properly depressed and that you have a mode light on (applies to LE manual system). My kids have occasionally pressed a button part way and that seems to actually disable the fan and sometimes the temp control.

Manual or automatic? Exactly what's it doing? Fan and mode works but no heat? Front working properly?
Oh yeah, I've pressed the buttons (set it to floor), and the rear temp control knob is set to full hot. It's a manual a/c system, and the blower and mode buttons work. Plenty of heat from the front. I could spend the $15 to get the info from TIS, but I'd like to avoid that.

Regards,
Steve

'08 Sienna LE FWD
'13 Tacoma PreRunner SR5 Double Cab Long Bed Texas Edition 4x2
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#12 Old 01-03-2014, 05:52 PM
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OK, so to start with, you need to see if you are getting hot water to the rear heater core. There is a solenoid control on the water line on top of the rear unit. I've made you a composite of some images I grabbed off the web to get you started on the disassembly process:



Here's a drawing with some landmarks:



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#13 Old 01-03-2014, 06:13 PM
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Service manual instructions are pretty scant. You may be looking at a physical clog in the lines, a bad solenoid, or an electrical control issue. Do you see the control arm move when you work the panel knob? Can you move it manually? You can manually turn on the valve using a 12v jumper.

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