After a control module here, a coolant leak into the cylinder head there, it was latter discovered that there is a filter inside the heater core that is not in any maintenance book or diagram.
This actually makes more sense. Perhaps they removed this and cleaned it thoroughly on the outside which allowed air to pass over it and a good pressure cleaning for the inside pushed debris that was lodged inside that then allows fluid to travel through the smaller tubes. With the bad head gasket he had to start with this would make complete sense.Looks like that would be fairly easy to access. I don't have heat issues but I think I'll look at my car tonight just to inform myself.
It appears that the heater core actually looks like this. I wonder if the OP is mistaking that for a filter or if there is something else in there somewhere.
Given it's physical location I could see garbage sucked in from the outside (leaves and other debris) collecting on top of that core and restricting airflow.
This page also has a nice diagram breakdown of parts
FYI this filter is not "in the heater core" itself. It is technically in the hose between the heater core outlet and the 3-port valve inlet. If you trace that line just in behind the engine next to the bulkhead you will find a pair of hose clamps in the middle of the hose that once removed allow the removal of the filter.Reed Lalier chevrolet in fayetteville, NC: After my 3rd trip to the dealer this winter they solved the heat issue. background:
The car could not provide heat despite maxing it out on the screen. After a control module here, a coolant leak into the cylinder head there, it was latter discovered that there is a filter inside the heater core that is not in any maintenance book or diagram. Its like a ghost part, nobody knew it was there except some master mechanic on some national Chevrolet hotline the dealer called for last resort advice. Sure enough, this cylinder looking filter (think refrigerator filter cartridge) was like "swamp" dirty. Its not a consumable part, it just gets cleaned and put back in. After cleaning/unclogging it, the heat was there.
This is a pre-owned volt for us that we got in the summer and we're experiencing the real heat for the first time.
I hope this helps other Volt owners with heat issues. Ask the dealer to check that filter inside the heater core near the firewall. They might not know it exists because like I said, this thing doesn't appear in any or most maintenance books/diagrams.
200-300 dollar job, but the dealer was nice to us (free) with a loaner. That's what happens when you don't get impatient and you work the survey system respectfully. Feel free to email me at ([email protected]), I would love help other volt owners if it comes to it.
Thanks for this info WOT. My 2013 Volt is experiencing this problem. Rick Hendrick Chevy here in Duluth GA has a handful of experienced Volt technicians whom I think will be able to accurrately diagnose & fix it, but I still like to be involved to help prevent mistakes if I can (i.e., if they come to me with request to do something more than check the filter, I will know to ask if this inspection has already been done). Hopefully it will only be the filter, and that is all that gets touched.FYI this filter is not "in the heater core" itself. It is technically in the hose between the heater core outlet and the 3-port valve inlet. If you trace that line just in behind the engine next to the bulkhead you will find a pair of hose clamps in the middle of the hose that once removed allow the removal of the filter.
The filter designed to prevent foreign debris from entering the valve and pump in the event of a contamination, is not considered to have any scheduled maintenance.
However when properly following the diagnosis of a low/no heat condition (with no DTCs) the "Heating Performance" diagnostic chart specifically directs the technician to check this filter. The presence of this filter is also covered in the Volt technician training.
So they simply missed it somehow...