Thanks to record earnings by Johnson Controls Inc.'s power solutions business segment, the company's net income shot up to $300 million in its fiscal fourth quarter from just $16 million in the same period last year.

Net sales in the three months ended Sept. 30, however, slid 15.5 percent to $7.87 billion from $9.3 billion a year earlier.

"We entered 2009 with two of our markets—North American automotive and residential HVAC (heating, ventilation and air conditioning)—already depressed. As the year progressed, we navigated through customer and supplier bankruptcies and deteriorating global economic conditions," Stephen A. Roell, chairman and chief executive officer of the lead-acid battery maker, said...