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Discussion Starter #1
My air conditioning blows ice cold when in electric mode. However after switching to ICE, whether by selecting hold or automatically after electric miles are used, the air begins to blow piping hot from the vents within 1-2 minutes, even though I have made no changes to the climate control settings.

Just to eliminate the possibility I hooked up my gauge to the ac lines and everything is operating as it should, no leaks and not overfilled with freon.

When I google searched the problem I found a Consumer Reports complaint on the exact same issue:
“A few miles after the car switches from battery to gas powered, the climate control system starts blowing hot air even though the A/C settings haven't changed”
Anonymous, FL (2014 Chevrolet Volt None Plug-in Hybrid)

Before I take it to the Dealership, any suggestions? Sounds to me like a computer or software issue?
 

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My air conditioning blows ice cold when in electric mode. However after switching to ICE, whether by selecting hold or automatically after electric miles are used, the air begins to blow piping hot from the vents within 1-2 minutes, even though I have made no changes to the climate control settings.

Just to eliminate the possibility I hooked up my gauge to the ac lines and everything is operating as it should, no leaks and not overfilled with freon.

When I google searched the problem I found a Consumer Reports complaint on the exact same issue:
“A few miles after the car switches from battery to gas powered, the climate control system starts blowing hot air even though the A/C settings haven't changed”
Anonymous, FL (2014 Chevrolet Volt None Plug-in Hybrid)

Before I take it to the Dealership, any suggestions? Sounds to me like a computer or software issue?
How long? Forever, or for a few minutes then goes back to cold?
 

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Discussion Starter #4
It's a 2013 with 110k miles. Very solid car with no other problems. Once it switches over to ICE, it will keep blowing hot until the car is stopped and left to sit for several hours to cool down. Then, if run on electric, it will blow cold, but once switched to ICE again, hot air within 1-2 minutes.
 

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might be the airflow control doors in the HVAC unit

I first thought it was the two-way coolant flow control valve shown in the thread jbakerjonathon linked to, but the diagram indicates it is supposed to route hot coolant to the heater box when in range extended mode. So that would be normal operation.

So it seems more like the heater box itself, which mixes cool air and warm air, may be at fault. This is usually done with flapper doors, and they are usually controlled by engine vacuum, though on a volt, which normally doesn't have engine vacuum, I suspect they may be electric.

You can see a diagram of the HVAC components that do this here, at GMpartsdirect: Part # 17, "Temp Motor" seems especially likely.

One thing makes sense with this as the cause is that even with the air mixer doors not behaving right, in Electric mode, there'd be no hot coolant, so the AC would be expected to work and deliver cold air, even if the flapper doors were routing air past the heater core.

This isn't a perfect fit to your symptoms, but worth checking out.

-Lumos
2014 gen 1
 

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So it seems more like the heater box itself, which mixes cool air and warm air, may be at fault. This is usually done with flapper doors, and they are usually controlled by engine vacuum, though on a volt, which normally doesn't have engine vacuum, I suspect they may be electric.
+1. You might want to check for a blown fuse.
 

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Most likely a temp door actuator or a bad coolant flow valve. There is a valve that controls the flow of engine coolant to the heater core. Both can be recalibrated to check for proper operation but that takes a good scan tool to make happen.
 

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Also noticed a similar issue today:

Normally I have the chance to charge my car every evening, so my car is always running on Electric mode during the heat of the day.
Last night, I stayed at the girlfriends house with no opportunity to charge.

When I started the car via keyfob to get the cabin temperature down, I climbed in a few minutes later to find the cabin still VERY warm. A quick check of the Climate screen showed that I was still in Auto mode, set to 71 with Comfort selected (which normally keeps the cabin very comfortable during the heat of day), yet there was ambient temperature (~85 degree) air coming out of the vents.

I waited a few minutes to see if the car would sort itself out, with no change in fan speed or air temperature. After fiddling with it for a while, the only adjustment that seemed to change the outcome was to crank the temperature setting way down. The CC system seemed to resume 'normal' operation only after the temperature setting was lowered to around 62 degrees, far below the actual cabin temperature, which was easily north of 80 degrees.

Thought this situation might be related to OP's because we were both operating in Range Extending mode when it occurred.

Any thoughts?
 

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Discussion Starter #9
Daddygoose, I can't say whether your issue is related. The suggestions here were right on for me though. I sent the thread to my mechanic. He mentioned something about the voltage of the alternator being higher when the engine is running and this affecting the operation of the blower door actuator. It turned out to be the "Heat Blend Door Actuator", GM Part # 13372987. $20 new on Ebay and about 15 minutes for the mechanic to change out. The old one looked like it had partially broken apart. I just drove over 100 ICE miles straighter after 47 electric miles and the AC was still ice cold. Problem solved. Thank you everyone for your suggestions!
 
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