@rasterman might be able to point out a good thread on the subject. (maybe with a google pic search of the site, this is a good way to dig up the exact thread of old relevant discussion).

 

This is original factory install on my 07:

Another way to check is to follow the rubber hoses. One should connect to a metal pipe that runs a short distance and connects, at a flange, to the water pipe. The water pipe (goes across the top of the engine) is the source of the hot coolant for the heater core.

The other hose connects to a metal pipe that runs horizontally to the front of the engine. This goes to the inlet side of the pump, through which it returns to the engine. This is the outlet from the heater core.

Incidentally, based on this configuration, and diagrams/photos of the core, it seems that the flow through the core is "up", that is, the hot coolant enters the core at the bottom, and comes out of the core at the top.

 

The picture is great, but, the additional description hit the spot, needed!

 

Did you fix your problem with no heat on the passenger side? I have the same problem on my 08, I backflushed the heater core today but it didn't fix the problem.

 

Heater cor Inlet/outlet ID

I have a 2009 Outback with no heat. Control and cable appear attached and functioning. I saw a reply from 2017 posted by an 08 owner that the core flush did not solve his heat loss. Please reply if there is more info on the subject why the heater is not working after a flush. Thanks

 

I had to get the heater core replaced on the 2008 that I used to own to fix the problem. Apparently the core is parallel flow not series so if the passages on the passenger side clogs which is usually what happens first then you have no heat on the passenger side. I tried everything to get it to flush out with maybe a 10% improvement.

 

Thanks, I guess i will try the flush, forward and reverse as i have seen recommended, and see what happens. I'll post the results.

 

Same issue, new question

I finally picked up a Chilton manual for my 09 Outback. It does not list much troubleshooting info about the heater system. But one thing it says is that if one hose is cold and the other hot there is a problem. What about when both hoses are hot and there is still no heat?

 

I understand the flow. If the inlet hose is hot and the outlet is cold i would expect that to indicate a blockage of flow in the heater core. But when they are both hot there must be flow. Why no heat?

 

Is your car a limited with automatic climate control? You may have an issue in the box that's preventing the flapper door or whatever it is from opening allowing heated air to make it through to the hvac system.

I'm not super familiar with the internal workings of the the hvac system but I wanted to put out an alternative source of problems in hopes of keeping you from barking up the wrong tree thinking the issue is the heater core and not the heater system itself.

 

Adding to @aesthetic.rake, the "flapper" idea could apply to the manual HVAC system as well. The temperature control is connected to the vane by a "bicycle" cable. If the cable is disconnected from the vane, or the outer housing of the cable isn't fastened in place, there's no control of temperature and, if the vane was in the cold position before, it stays there.

@Mariposawrick

When was the last time you used the heater and it worked?

Was the front passenger airbag recall done sometime between then and now? The heater control panel etc., is usually removed as part of that work, and there was at least one case here where the cable had not been reattached.

 

It's been over a month since i checked this forum. Thanks for the comments and questions to guide me. So far, this is what I have:

heater worked until I replaced the stereo/CD player. There was no interefering recall work since.

Had a shop look at it.They confirmed the cable and control are functioning but said the new stereo could be interfering with cable travel or the control mechanism moving when dial is turned from cold to hot. I have pulled the radio and can put my hand into the cavity to make sure the cable and white plastic control mechanism moves when the dial is turned.

Both hoses are got to touch after motor has been running. Would this tend to show there is flow of the hot coolant into and back out of the heater core? Would this also tend to suggest no air blockage or other need for a flush?

Does that leave me with the issue of blend door or flap not moving somewhere, impeding the flow of heated air into the cabin? One person suggested that if it was in cold position when it stopped opening it would stay that way, hence cold air.

Sometimes i think I sense slightly warm air when the temp dial is in mid position. Does this help to suggest that there is flow in the core but no opening for the heat to come into the cabin?

Thanks to all in the Forum for helping.

 

. . . heater worked until I replaced the stereo/CD player. There was no interefering recall work since.

. . I have pulled the radio and can put my hand into the cavity to make sure the cable and white plastic control mechanism moves when the dial is turned.

Here's a diagram of the mechanism on the side of the heater box. The cable comes up from the hot/cold control dial, and moves a lever which is attached to a vane inside that controls how much of the incoming air passes through, or by, the heater core. Is this the mechanism that you checked?

When you replaced the radio, and probably had to remove the heater control and disconnect the cable, did you have any difficulty, especially removing the cable? The cable outer casing has to be clamped in place. In the diagram it looks as if it's clamped to the mechanism. It might also have to be clamped at the temperature control end. If the casing isn't held in place, as the temperature control is rotated, the whole cable will move rather than just the center cable core, and so might not move the lever at the vane through its full range.

Both hoses are got to touch after motor has been running. Would this tend to show there is flow of the hot coolant into and back out of the heater core? Would this also tend to suggest no air blockage or other need for a flush?

Yes, it's a reasonable indicator of flow through the core. When the heater blower is on, and the cold air is passing through the heater core, the core outlet temperature might be lower than the inlet, reflecting the heat that was used to warm the air going into the cabin. But if the vane inside is bypassing the air around the core, the inlet and outlet temperatures will be closer. They could be checked with an IR thermometer held near each tube where it comes through the firewall.

Does that leave me with the issue of blend door or flap not moving somewhere. . .

On my 07, with the car off, parked in a quiet area (e.g. garage), if I turn the temperature control to the full hot end, at the last step there's a dull thud that appears just as the control stops. The sound appears to be coming from above the heater controls, perhaps from the center, face level, vents or just above. I believe this is the vane reaching it's fully closed position, (i.e., all air is directed through the heater core). I haven't tried this on another manual HVAC to see if all are this way, but it might be something to try. If there's no similar sound, then it's not conclusive that the vane isn't working, but it leaves that as a possibility. Of course, I could be wrong about the signifcance of the thud . . .

Sometimes i think I sense slightly warm air when the temp dial is in mid position. Does this help to suggest that there is flow in the core but no opening for the heat to come into the cabin?

The opening for the air to come into the cabin through the vents is controlled separately. If, when using the air conditioner, or even just turning the blower on high, there's plenty of air coming through the vents, and it can be changed from the floor outlets to the face-level vents or to the windshield, then it's unlikely the lack of heat is because of a blocked opening into the cabin. (I presume that even if there's no heat, the air flow when the heater should be providing warm air is as strong as when using the AC. Is this correct?)

Was your 09 subject to the front passenger airbag recall? If yes, was it done? And, again was this before or after the stereo work was done?

 

To add one further tidbit, the AC works fine and cold air blows in through all vents when it is operated.

 

My thanks to all on this forum who gave suggestions for the fix I needed. It turned out to be a disconnected actuator cable end near the steering column. Quite difficult to find and to fix but it works now. No flush, no core replacement issues, just a cable I must have disconnected when I replaced our defunct stereo over a year ago.

 

To Plain OM, you answered all my last questions and it helped me a great deal to see what the connection looks like. I did not stay at the computer to get your reply so i did not see the diagram before I spent a couple hours taking off trim and looking and fixing, but seeing the diagram now tells me I did almost exactly what was needed. I still need to go back and make sure the flange on the end of the cable housing fits into the notch to hold it. I got the cable into the clamp without really knowing it should be there but it looked like it should and it fit without changing the route of the cable or pinching it. The dial does not rotate all the way to cold but the heater is flowing just fine. My wife thanks you too.

 

have very similar problems mariposa, and think its something I did after the radio install cause I checked everything else and all is good, do you have a picture of this cable by the steering column, that would help a ton, thanks for all the info, I dont think it's my heater core and all the actuator motors are working a o k , so I'm down to a stuck door somewhere too.
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