The key driver for supply company Johnson Controls (NYSE:JCI) will be how fast its building-efficiency and power-solutions businesses can offset stagnant-to-declining automotive sales tied to Detroit's Big Three. First-quarter results released Friday shed some light on the subject.

For the quarter, building efficiency sales grew an impressive 62% to $2.9 billion, while sales in power solutions grew a respectable 10% to $1.1 billion. Automotive sales fell 11% to $4.2 billion, yet the segment still accounted for more than half of total sales. That's down from 57% for all of fiscal 2006, but it shows that auto sales will continue to drive the fortunes at Johnson Controls for the foreseeable future.

The company is also relying less on the Big Three -- General Motors (NYSE:GM), Ford (NYSE:F), and Daimler Chrysler's (NYSE:DCX) Chrysler division. Back in 2004, they collectively accounted for 39% of Johnson's total sales; that number fell to 32% for 2006. It's hard to tell whether the decrease is an active decision by management, or more reflective of the Big Three's falling market share -- it's likely a combination of both factors.

In any case, Johnson's top-line expansion hinges on its non-automotive businesses. Overall, the company is holding up as well as any auto supplier, including Lear (NYSE:LEA) and Visteon (NYSE:VC). Management is projecting total sales growth of 6% for fiscal 2007, and growth in diluted earnings from continuing operations of 14%.

The one drawback I see is that Johnson Controls operates in capital-intensive industries that eat up a good portion of the operating cash flow produced every year. Its debt levels are moderate, but it has to continuously spend to maintain operations, and it will have to pursue acquisitions to enhance organic growth in its building efficiency and power solutions businesses.

Johnson Controls' management has proven quite adept at managing uncertainty, but there's more of it as the automotive business struggles and the firm enters newer markets (such as its acquisition of York International in 2005). It's a close call -- the company has a reputation for conservative growth, but the stock is bumping up against its 52-week highs amid an overall market run-up. I'd be more intrigued with any pullback, so for now, I'll keep the company on my watch list.

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Fool contributor Ryan Fuhrmann has no financial interest in any company mentioned. The Fool has an ironclad disclosure policy. Feel free to email Ryan with feedback or to discuss any companies mentioned further.