Volvo electrical question

1999 Volvo S70 with 135,000 miles. Car otherwise relatively trouble-free, but persistent electrical problem driving us slowly crazy. Car in Southern California and is kept in driveway, not garage. During summer, no problems. Last two winters, when car is started electrical accessories do not operate for first few minutes. These accessories include car windows, display lights, radio, heater, windshield wipers and back window defrost. Car starts immediately and headlights operate immediately. We have had Volve dealer investigate, keep car for a week, and then replace ignition switch without fixing problem. The next winter we had a private Volvo mechanic attack problem. He kept car for a week, and replaced ignition switch without fixing problem. I have asked if this might be related to fuses and dampness, but they have discounted this possibility. I would live with problem except not having windshield wipers is a safety issue this time of year. Wife wants to sell car but I want to keep. HELP!