Interestingly, it seems this wasn’t a fluke. Online industry and consumer forums turned up a host of similar cases. Consumers reported losing heat, A/C, power locks, power windows and radios after the Volvos (mostly model year 2001) had:

• a jump start;
• a new battery installed;
• the battery cables removed to clean the terminals.

The root of the problem appears to be residual power to the control computer, which causes a voltage spike when the battery cables are reconnected. In other words, simply turning off the ignition isn’t enough. A period of time must pass before all of the car’s computer controls completely drain of power. (We would highly recommend removing the key from the ignition and waiting 20 to 30 minutes to disconnect the cables.)

In some of the cases we read about, consumers were lucky and were able to reset the climate control module by removing the battery cables and holding the terminals together for 30 seconds. In other scenarios, an auto repair shop was able to reload the climate control software. But in severe cases, like our client’s, the climate control computer needed to be replaced.

If you have any battery or starting issues with these vehicles, I strongly recommend relying on your favorite automotive technician. I realize I have an inherent bias in saying that, but the $1,600 risk isn’t worth saving a $100-$200 trip to the shop for a new battery. If you are determined to tackle battery problems yourself, exercise every caution to ensure the modules are powered down.