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Discussion Starter #1 (Edited)
I searched the forums and couldn't find anyone that has had this same problem.

We have two Volts, both 2013's. Mine has 66k miles on it, Wife's has 42k, and it's 12 month CPO warranty was up in May. :mad:

Tonight on our way to dinner, the climate control was set to comfort, and 70 degrees. It was about 90 outside.
I realized that the air isn't moving and that it's getting warm. So I start bumping the temp down, the wife usually keeps it warmer than I like, so I didn't think anything was unusual. By the time I realize that I'm setting it to 65 and the vents are barely blowing, I think there might be a problem. We get to the restaurant, eat, and then leave. I had hoped that "rebooting" the car would clear up the problem...Hey, it works when my display freezes!

On the way home it didn't self heal. The heater is definitely on WITH the AC. Cool'ish air coming out of the vents but you can feel warm air with it. It's weird. Stopped in the driveway the power meter on the dash was showing between 4-5kW...heater obviously on.

Any ideas?

Summers in Kansas can be brutal...that AC needs to work! But the dealerships here are pretty anti Volt...and didn't sell many. I'm worried the time for diagnosis will get real expensive real quick. Hopefully someone here has experienced this before and can tell me what to tell the dealer to get it fixed ASAP.

Thanks!

Some pictures of what the car was displaying while trying to cook us to death:
https://drive.google.com/file/d/1obZTUBqd9GdeMIZQdmoq015KMyPizenMSw/view?usp=sharing
https://drive.google.com/file/d/1UnRYPPJ1-H7AxOL0U0-bUG2TZAkeL6AWfQ/view?usp=sharing
https://drive.google.com/file/d/1SlJ9o7mxY_kh-WfdOVPs9GwzQm6INHGaKg/view?usp=sharing
 

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If the auto dehumidify feature is turned on, the heater can come on with the AC in order to improve dehumidification. That feature is turned on or off by a check box in comfort settings. You should also check the coolant levels. There are pictures of where those should be in the FAQ section of the forum.

Edit: The search function of this site is not the greatest. You can use google to do a site search of just this site. For example in a google search box enter "site: gm-volt.com too much heat" without the quotes. Also, I recall that a while ago a member had a problem with a stuck damper in the HVAC system that may have resulted in too much heat. Good luck and please report back the nature of the problem and the solution.

KNS
 

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Discussion Starter #3
The auto dehumidify feature is off. It was one of the first things I checked.
Also ruling that out, the heater ran for the entire drive home. It didn't cycle on and off like it does when it's performing that function.
 

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If the auto dehumidify feature is turned on, the heater can come on with the AC in order to improve dehumidification. That feature is turned on or off by a check box in comfort settings. You should also check the coolant levels. There are pictures of where those should be in the FAQ section of the forum.

Edit: The search function of this site is not the greatest. You can use google to do a site search of just this site. For example in a google search box enter "site: gm-volt.com too much heat" without the quotes. Also, I recall that a while ago a member had a problem with a stuck damper in the HVAC system that may have resulted in too much heat. Good luck and please report back the nature of the problem and the solution.

KNS
Isn't it the other way around, in the winter with the heat on the AC compressor kicks in to dehumidify?

I'm guessing there is a bad temp sensor somewhere and the car thinks it's freezing cold when it isn't. But that's just a guess, it's really hard to diagnose without seeing the car.
 

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Isn't the A/C covered under the 8yr/100k Voltec warranty since it is an essential part of the battery's thermal mgmt system?
 

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A few thoughts:

1) Did you install one of the methods to defeat the ERDTT? Those mess with the temp sensing data.

2) You didn't say that you tried the "auto" button. It is worth trying that in case you have some odd combination of manual settings.

3) Did you try pulling the #5 fuse in the fuse panel by the driver door to reset the HVAC?

4) What if you set the temp as low as it will go?

5) As for warranty coverage, my dealer says that problems with the heater (possibly excluding the electric heater element itsself) are not covered under the voltec or powertrain warranty. I suspect they will define this problem as a heater problem rather than an AC problem, in which case it wouldn't be covered.
 

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Discussion Starter #7
A few thoughts:

1) Did you install one of the methods to defeat the ERDTT? Those mess with the temp sensing data.
Nope, car is bone stock
2) You didn't say that you tried the "auto" button. It is worth trying that in case you have some odd combination of manual settings.
It was originally on auto when it started trying to cook us. 90 outside, thermostat set to 70 and comfort. The fan was barely blowing.

3) Did you try pulling the #5 fuse in the fuse panel by the driver door to reset the HVAC?
I disconnected the 12V battery for an hour or so, that didn't fix it.

4) What if you set the temp as low as it will go?
Dropping the temp until it says "LOW" sped up the fan, but not to its max. The air coming from the vents was cool, but not cold. Display was still showing 5kW while parked. So clearly, the heater was still running

5) As for warranty coverage, my dealer says that problems with the heater (possibly excluding the electric heater element itsself) are not covered under the voltec or powertrain warranty. I suspect they will define this problem as a heater problem rather than an AC problem, in which case it wouldn't be covered.
I'm afraid you're right.
Seems like we're on about the same page...any other guesses!?
 

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Discussion Starter #8
Isn't the A/C covered under the 8yr/100k Voltec warranty since it is an essential part of the battery's thermal mgmt system?

Technically, the AC is working, so any coolant loops are doing what they are supposed to do. Problem is, the heater is running at the same time, cancelling the AC out.
 

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Discussion Starter #9
Isn't it the other way around, in the winter with the heat on the AC compressor kicks in to dehumidify?

I'm guessing there is a bad temp sensor somewhere and the car thinks it's freezing cold when it isn't. But that's just a guess, it's really hard to diagnose without seeing the car.
Would a bad/failing temp sensor show up on any kind of scan? What I'm really trying to do here is narrow down what I want the dealer to start with. If I just give them the car and tell them what it's doing, they'll "diagnose" the problem for 8 hours at $100 an hour. My two local dealers really aren't Volt friendly and have a bad habit of making problems worse to support their case that Volts are not good cars.
 

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You are saying the heat is "on" based on the kW display. Are you also seeing the heat icon in the climate screen turning on? If that icon is not on, this could be a problem isolated to the AC refrigerant charge and/or compressor.
 

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Discussion Starter #11

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Try taking the system out of auto mode and do a manual mode to see if the heat is turned off. There is a temp sensor on the windshield used to help keep the windshield from fogging up and there are also a few temp sensors in the vents as well. The ambient temp sensor seems to be working from the looks of your pic so that sensor should be good. The last sensor is the humidity sensor, all these sensors are the same as other cars in the GM line up so your local dealership should be able to find the problem if it is related to a sensor issue.
 

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Discussion Starter #14
Try taking the system out of auto mode and do a manual mode to see if the heat is turned off.
Behavior was the same in both manual and auto modes.

Any chance anyone has any diagrams where the sensors are? Couldn't hurt to find them, unplug and then reseat.
Don't know how many things I've "fixed" that were just a loose connection...
 

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There's three sensors in the HVAC case, one sensor on top of the dash and one up front, by the grill.
 

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I think the humidity sensor is one of the relevant sensors. Isn't that is up by the rear view mirror?

I think there may be some problem with humidity sensing (among other things), because running heat and AC at the same time sounds like an effort to lower humidity.

On the other hand, the sensing might be accurate, but the logic about what to do with the data might be what is out of whack.
 

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Had the AC been running for a while before the airflow closed off then it started blowing hot? If so, I've seen this before a couple of times and it specifically happens under very humid conditions, while on Comfort, and usually after about 20-25 minutes of driving. What I've guessed is happening is that the condenser portion of the cabin loop gets frosted over, the car figures out that's what's happened somehow, then it blasts hot air at the condenser coils for a couple minutes until airflow is restored, then it goes back to cooling. And yes, auto-defog is always on for me. I've never seen it repeat during a drive, and I don't remember it happening twice even in a couple day span. (And the last time it happened to me it was ALSO around 90F but I don't remember enough about the the other times to know for sure that it wasn't 100 or 80. Just that my mind latched on "humid as hell" and "frosted over".)
 

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Discussion Starter #20
Had the AC been running for a while before the airflow closed off then it started blowing hot? If so, I've seen this before a couple of times and it specifically happens under very humid conditions, while on Comfort, and usually after about 20-25 minutes of driving. What I've guessed is happening is that the condenser portion of the cabin loop gets frosted over, the car figures out that's what's happened somehow, then it blasts hot air at the condenser coils for a couple minutes until airflow is restored, then it goes back to cooling. And yes, auto-defog is always on for me. I've never seen it repeat during a drive, and I don't remember it happening twice even in a couple day span. (And the last time it happened to me it was ALSO around 90F but I don't remember enough about the the other times to know for sure that it wasn't 100 or 80. Just that my mind latched on "humid as hell" and "frosted over".)
Kansas and "humid as hell" are pretty synonymous. This explanation makes the most sense of anything. The car hasn't done it again since and we're just keeping an eye on it.

If it happens again, I'll be sure to update.

Thanks for all the good tips everyone!
 
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