General Motors Corp. said today that it was recalling about 720,000 vehicles to fix two problems that could cause their air bags to malfunction in a crash. GM said one recall covers about 570,000 full-size Chevrolet and GMC pickups and sport utility vehicles built in model year 2000. The automaker said the vehicles had air bag sensing and diagnostic modules that could interfere with air bag deployment. The modules will be recalibrated by dealers. The other recall covers 150,000 cars, SUVs and minivans built between May and June 2002. GM said about 8,000 of those vehicles have air bag inflator modules that could crack open if the bag deployed, leaving the bag less than fully inflated. GM said both problems were discovered during testing. The vehicles will be repaired at no charge to their owners.