I have a 2011 Suburban Z71 and have noticed that when my car is off (keys out of the ignition) and have left for a while. When I return to my car, sometimes the air conditioning vents in the front are blowing air. Also the fan in the back of the rear storage area (on the right side) is on.

I didn't know if this is normal or not. Anyone else notice this?

 

Yes that is normal if you have the "after blow" feature enabled in your software... if helps reduce the build up of mold in the AC evaporator so you don't get the musty smell... as far as I know all 07 and up have the feature available but some are enabled and some are not... It can be a battery drain concern...

 

Ahh ok. I never noticed it until I took it to the dealer for that musty/moldy smell. They cleaned the vents out with a cleaner to help with the smell. They must have turned it on when it was at the dealer.

What is the best way to keep the musty/moldy smell out of the car when it gets turned on and the AC starts blowing?

 

For those that don't have the after blow feature ( and I guess for those that do too) if you can remember to turn the AC off but leave the fans blowing ( actually turn them to high) a few blocks before you plan to stop and turn off the engine you will accomplish the same thing as the after blow...

What you are wanting to do is dry out any moisture/frost build up on the evaporator coil under the dash, its this moisture that causes the smell when it gets warmed up from the outside heat turning it into a breeding ground for mold...
This happens because the evaporator is in an enclosed area and no normal air reaches it to dry it out when your not driving and the fan is not turned on....

If you could easily reach the evaporator( which most of the time you cannot) a regular spraying of Lysol would do the trick...

 

I assume in a suburban we can't reach the evaporator?

After they sprayed the stuff at the dealer, I can still smell the musty stuff. Hopefully it'll go away with turning the ac off.

I'll try to remember to turn the ac off a few blocks from the house.

 

I have not accessed mine so I cannot speak with absolute authority, however looking at the service manual you may have partial access to the evaporator by removing the blower motor....


From the service manual...

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:

Connect the Scan Tool.
Turn ON the ignition, with the engine OFF.
Build the vehicle with the scan tool.
Select HVAC Control Module
Select Module Setup.
Select Afterblow Option.
Upon selecting the afterblow option a asterix will appear next to the word afterblow meaning the function is enabled.
Select the save option in the lower left of the screen.
When afterblow has been enabled by the scan tool the blower motor will operate at 68 percent blower speed for 2 minutes 30 seconds to 4 minutes after the engine has been in Key OFF for 30 minutes.

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

• The outside air temperature must be at least 21°C (70°F).

• The A/C compressor must have operated during the latest key cycle.

• The engine must be turned off for at least 30 minutes.

• The system voltage must be at least 12 volts.








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Thanks for all the information! Hopefully that smell will just go away if I keep turning the AC off and leaving the fans on before I turn the car off.

Thanks!