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Discussion Starter · #1 ·
Well, with less than 400 miles remaining on my GMPP it looks like it's getting some use today. I had a coolant service done on 9-1 since my '13 hit 5 years and recently discovered I lost nearly all heater function. Unsure if it's related, but I did mention it to the SA. I get slightly warmish air in EV mode (maybe 80* out of the vent) and ice cold air when in gas mode with the temp set to hi. I did notice that I can hear what sounds like coolant boiling faintly inside the dash near the floor vents so I'm going to assume that along with the warmish air in EV mode there isn't a problem with the heating element. Has anyone else experienced similar symptoms? I'm hoping it's a simple fix such as maybe programming but glad to know that if it's more serious such as a valve or even a heater core that it should be covered, especially since I understand heater repairs on the Volt can be pricey.

I'll post back when I get the diagnosis from my SA, but my understanding is that they may have to keep the car overnight.
 

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.... I had a coolant service done on 9-1 since my '13 hit 5 years and recently discovered I lost nearly all heater function. Unsure if it's related, ....
Of course it's related. The turkeys didn't the the engine and heater loops 'burped' correctly. They share the one heater core in the cabin of the car.
Don't let them charge you a dime. And just smile when they give you their excuse!

Good luck !
 

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Discussion Starter · #3 ·
I suspected the same, but shouldn't an air bubble work itself out? I've ran plenty of gas miles since the coolant change, with a several of them attempting to get the heater functioning with no success and no change in coolant level at the expansion tank. Combined with the sound of water boiling and little heat function I'm more tempted to suspect a valve isn't opening, or possibly even the temp door (if applicable). I'd hope it's not a heater core, but that would certainly be covered I'm sure.
 

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I agree, the recent coolant service and the bubbling sound seem related. I think they did the job wrong. Take it back.
 

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Discussion Starter · #5 ·
Well, got the update just a couple minutes ago. It's a failed heater coolant control valve and filter. Apparently the parts needed are in LA and Michigan so it'll take a couple days to get my car back it seems. Just waiting on GMPP to approve the repair and parts to get shipped and installed. Shoulda waited to do my coolant service as then I could have had it done free with the repair.
 

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Well, got the update just a couple minutes ago. It's a failed heater coolant control valve and filter.
Goes to show that the internet can't diagnose a car issue worth a damn (as if we needed more proof). Nice to see you went to the source first and thanks for sharing the results. This is how it should be done.
 

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Discussion Starter · #7 ·
Goes to show that the internet can't diagnose a car issue worth a damn (as if we needed more proof). Nice to see you went to the source first and thanks for sharing the results. This is how it should be done.
Agreed. And I actually have to suspect since there is a filter involved in the repair that perhaps the problem was set off initially by the coolant flush done last month. Perhaps some debris dislodged and clogged some filter causing a coolant restriction. I know last winter the heater performance wasn't great, but it was ok, though here in central california it never gets terribly cold. I could certainly see it not being adequate in real cold climates so perhaps this issue has been at play for a while and the coolant flush completely blocked the flow of coolant.

The bonus in all this is that they also informed me that it's completely covered by the GMPP warranty. I realize this is just one repair toward the end of my coverage which only has about 400 miles remaining, but all in all I'd say it just about broke even as other than this issue, I also had a window regulator covered, and the day I bought it, it also covered a replacement key. Not sure what the previous owner had as far as claims, but glad I was able to benefit from it.
 

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Agreed. And I actually have to suspect since there is a filter involved in the repair that perhaps the problem was set off initially by the coolant flush done last month. Perhaps some debris dislodged and clogged some filter causing a coolant restriction.
Sounds reasonable and it's something for others to look out for.
 

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Discussion Starter · #9 ·
Got the car back today. I managed to test the heater on the limited drive home (3 miles). EV operation seems to be blowing quite warm, and could tell with the engine operating in hold mode on the freeway that heat output decreased slightly, then increased. I assume it occurred that way due to the valve opening from closed loop EV operation to opening to include the engine circuit and the temp difference caused the slight momentary decrease in temperature. Hopefully that's the last issue I have for a while.
 
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