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Discussion Starter · #1 ·
I got this feature enabled by the volt tech at the dealership yesterday. They gave me a document (attached here also) that describes how to enable and the conditions that need to be met for the fan to blow. Here are the stated conditions:

The vehicle must be turned off.
The outside air temperature must be at least 52F when the compressor was last operating before the engine was turned off.
The AC compressor must have operated for at least 2 mins before engine was turned off.
The system voltage must be above 12 V.


I met all the conditions outlined yet I don't hear any fan blowing after I turned off the car. The only thing I can't test/tell is the last condition (system voltage), but I am assuming it is above 12 V. The car is just 3 months old.


Anyone with Afterblow, how/when does it kick in for you?

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I resisted the temptation to make about 6 different possible off-color jokes about Afterblow, and instead will make this much lamer joke:

I guess the volt tech blew it.

More seriously: what the heck is this afterblow and why is it useful? (The image you attached is so small I can't read it.)
 

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The after blow feature is designed to mitigate that funky mold and mildew odor that sometimes blasts from a vehicle's vents after having recently used the air conditioning while driving the car. The blower stays on for 5 minutes to help dry off the internal AC coil inside the cabin heat exchanger.

You can do this manually as well if you remember to turn off the AC compressor and just let the blower run on high for a couple of minutes prior to shutting off the vehicle. I have been doing this all summer and I rarely sense any odor from my Volt's climate control vents. I am not sure if it is best to run the blower with the climate control set to recirculate or to draw in fresh but warm moist air from outside (I set the climate control to recirculate for a few minutes and then fresh air for a minute longer before I turn the AC back on Auto and power down my Volt.)
 

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I had afterblow turned on in my Cruze and Volt. It doesn't run all the time. There also seems to be a humidity sensor so if it's not humid enough it won't run. Also, if the AC compressor wasn't running for the last few minutes prior to shutting off the car, even when using the air conditioning, the system assumes the air ducts have been dried already.

It kicks in 10 to 15 minutes after you turn the car off and runs for about five minutes. This is to give the ducts a chance to warm up first.
 

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The dealership enabled it on mine, but I have never actually verified that it works. Hasn't helped with the smell either, unfortunately.
Afterblow won't help once mold/mildew is established. You need to kill the mold/mildew through other means. If the car is still in the B2B warranty this is a free service. If you're out of warranty, turn the blower on low without the AC and spray lysol into the main cabin air intake.
 

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Do you know where the main cabin air intake is located? I've read that it is not easy to locate under the Volt's hood.
 

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Anyone with Afterblow, how/when does it kick in for you?
Afterblow Enabling
The afterblow mode can be enabled using the scan tool. The afterblow mode allows the blower motor to operate after the engine has been turned off. This operation of the blower motor dries the evaporator core, which reduces the amount of microbial growth which can create undesirable odors.

Use the following procedure in order to enable the afterblow mode:

1. Connect the Scan Tool.
2. Turn ON the ignition, with the engine OFF.
3. Build the vehicle with the scan tool.
4. Select Module Diagnosis.
5. Select Remote Heater and Air Conditioning Control Module.
6. Select Configuration/Reset Functions.
7. Select HVAC Afterblow Configuration.
When afterblow has been enabled by the scan tool the blower motor will operate at 68% blower speed, following the sequence below up to 5 times. This could last up to an hour:

1. The blower motor will be OFF for 7–11?minutes.
2. The blower motor will RUN for 25–30?seconds.

The following conditions must be met for the HVAC module to automatically operate the afterblow:

•The engine must be turned off for at least 30?min
•The outside air temperature must be at least 21°C (70°F).
•The A/C compressor must have operated for more than 2?minutes before shut down during the latest key cycle.
•The system voltage must be at least 12?V

FWIW: I've had afterblow enabled on my Gen1 for the past several years with negligible reduction in avail range when unplugged even with these multiple blower ON/OFF short iterations...
 

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As a matter of course I switch to fan only a few minutes before I reach my destination. Just automatic (for me not the car). Continues to blow cold air for a bit. mind you it rarely gets really hot here so don't know how that would work out down south in "the furnace".
 

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Discussion Starter · #10 ·
I had afterblow turned on in my Cruze and Volt. It doesn't run all the time. There also seems to be a humidity sensor so if it's not humid enough it won't run. Also, if the AC compressor wasn't running for the last few minutes prior to shutting off the car, even when using the air conditioning, the system assumes the air ducts have been dried already.

It kicks in 10 to 15 minutes after you turn the car off and runs for about five minutes. This is to give the ducts a chance to warm up first.
Yeah, about that humidity sensor. From the document that lists the required conditions, there is nothing about the humidity. So I am wondering if that is something they forgot to write down?

But thanks for letting me know about the time delay. I was expecting it will run right after I turned off the car, not 15 mins after. I guess I need to sit and wait in my garage for a bit to find out.
 

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Yeah, about that humidity sensor. From the document that lists the required conditions, there is nothing about the humidity. So I am wondering if that is something they forgot to write down?

But thanks for letting me know about the time delay. I was expecting it will run right after I turned off the car, not 15 mins after. I guess I need to sit and wait in my garage for a bit to find out.
The humidity sensor is the same one that tells the HVAC system to automatically switch to the dash vents when you're in cold conditions. All GMs seem to do this but I don't know if it's a standalone sensor or if they use a combination of sensors, including the external air temp sensor.
 

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As a matter of course I switch to fan only a few minutes before I reach my destination. Just automatic (for me not the car). Continues to blow cold air for a bit. mind you it rarely gets really hot here so don't know how that would work out down south in "the furnace".
I do this, too. I also keep it in recirculate mode while I am using the AC and while I am running it in fan only mode to dry. Recirculate mode helps reduce the amount of moisture it collects.

I live in a very hot, humid area where this is a problem in most cars. I have done this with all of my cars, and this really helps fight the funk. With the Volt, it does not always work quite as well, because sometimes the compressor runs for other reasons even in fan only mode. But it is still worthwhile. Once the funk develops, this method does not cure it, but it may help to diminish it gradually over several seasons.

I think afterblow is a great feature, but be aware that it will draw a certain amount of power from the battery while the car is off (no problem when plugged in).
 

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Discussion Starter · #13 ·
With the Volt, it does not always work quite as well, because sometimes the compressor runs for other reasons even in fan only mode.
This is the reason I turned on the afterblow, rather than trying to remember to do it manually. Even I am on the fan only mode, the AC is still on sometimes to cool off the battery. So this manual running of the fan is a waste of time for me as it is not doing what I wanted it to do.
 

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The after blow feature is designed to mitigate that funky mold and mildew odor that sometimes blasts from a vehicle's vents after having recently used the air conditioning while driving the car. The blower stays on for 5 minutes to help dry off the internal AC coil inside the cabin heat exchanger.
Oh...

I assumed this was just a GM attempt to keep up with Tesla.

 
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