I have been driving my wife's 2002 V70-T2.4 (turbo wagon, 115K miles), which we bought recently. Unlike our other 2002 V70 (NON-turbo wagon, 215K miles), this one turns ON the AC blower after the ignition is turned OFF. I read somewhere that Volvo engineers used this as a bandaid for their infamous evaporator problems - trying to eliminate condensation by turning the blower fan on after the iginition is turned off. Doesn't this drain the battery (I've noticed the blower stays on full speed for quite some time)? Does this really prevent premature evaporator failures?

Thanks,

Bernie

Yes, and it does dry off the evaporator. The computer keeps track of the battery voltage and turns it off when the level gets below 12V. No harm done.

My 850 doesn't do that, so I try to remember to turn off the AC about 1 mile before I get home. It's not completely dry, but I like to think that it helps.
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My back feels better when I sit in a Volvo seat

Hmmm - so the blower stays on until the battery reaches 12V, or is there any other parameter (like time) that the CPU uses to turn the blower off?

I wouldn't think time, rather temperature. There is a temp sensor next to the evaporator, which is prone to failure, and it might use that to turn the blower off/on.
--
My back feels better when I sit in a Volvo seat

Thanks Klaus - I found this on another forum, when searching "afterblow" :

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This is a copy of the latest tnn regarding afterblow from Volvo. Sorry its hard to read, but the information is still good.
NO: 87-53
DATE: October 5 2007
MODEL / YEAR S60 2001 -
S80 1999 - 2006
V70, XC70 2001 - 2007
XC90 2003 -
SUBJECT: Air Conditioning System Odor / Afterblow Function
REFERENCE: VIDA
This TNN superseded the previous 87-53, dated November 21, 2005. The changes
include: updates to the 1999 – 2004 method and added new method for 2005 and later.
Please update your files.
DESCRIPTION:
There may be cases of odor from climate system vents on the vehicles listed above. Ensure
the odor is not from some other source and all other A/C system checks have been
completed. If necessary the Afterblow function can be activated to dry out the ventilation
system and evaporator. There are two ways to activate the Afterblow function depending on
the Model Year (MY). For MY's 2005 and later see page 2 for MY's 1999 - 2004 see page 3.
NOTE: Up through 2002 Afterblow was activated from the factory, 2003 and later Afterblow
will be Retailer activated only.
SERVICE:
In all cases basic fault tracing needs to be performed prior to the afterblow activation. Once
this has been completed see the appropriate instructions for Afterblow activation.
Check / Verify that:
- There are no refrigerant leakages (not PAG oil causing the odor).
- AC drain is not clogged - drains sufficiently i.e. no water standing in the climate box.
- No water standing underneath the floor carpets.
- Cabin air filter inspected / verify it's been replaced according to the maintenance schedule.
- Battery is in good condition.
If all the above has been checked and confirmed that they are not the cause of the odor then
the Afterblow function should be activated to minimize the risk of odor.
NOTE: MY 2005 and later it is only necessary to activate / deactivate Afterblow one time per
vehicle. If ANY new software is downloaded the Afterblow function will stay activated.
Tech-Net Notes
“Fixed Right – First Time”
Volvo Technicians, Service and Parts Managers
Copyright ©2007 Volvo Cars of North America, LLC. All rights reserved. Page 2 of 3
MY 2005 and later:
MATERIAL for 2005 and later:
Description Quantity Part Number
Activate afterblow software 1 30782577
Deactivate afterblow software (if needed to turn off) 1 30782664
Activation / Deactivation through VIDA:
- Software Tab
- Software product
- Select 30782577 (or 30782664 to deactivate if needed). Enter part number if not listed
- Download software
Read - Out the status "active / not active" in VIDA:
- Diagnostics
- Vehicle communication
- CCM / Advanced
- After - run passenger control status (wording may change in future VIDA updates.)
Note: Active or Not-Activated
When certain criteria are met the interior fan will start to blow 50 minutes after the car has
gone into the sleep mode. The fan will blow for 15 minutes at half speed with the air
directed to the dashboard air outlets.
Make sure the customer is informed of this new function.
ACTIVATION CRITERIA:
Battery voltage greater than 11.9 V
Ambient temp greater than 75°F (24°C) when engine is turned off.
Runs only one time every 20 hrs.
MY's 1999 – 2004:
Activation and Read - Out the status "active / passive" in VIDA:
- Diagnostics
- Vehicle communication
- CCM / Advanced
- Programming the Climate Control Module (CCM).
When certain criteria are met the interior fan will start to blow 50 minutes after the car has
gone into the sleep mode. The fan will blow for 7 minutes at full speed with the air directed
to the dashboard air outlets.
Make sure the customer is informed of this new function.
Copyright ©2007 Volvo Cars of North America, LLC. All rights reserved. Page 3 of 3
ACTIVATION CRITERIA:
A/C compressor has been engaged for more than 4 minutes (continuously) out of the last 11
minutes before engine was turned off.
Ambient temp app 82°F (28°C) and A/C compressor running for more than 50% during a 10
second period