Driver side wheel keeps getting very hot

The brake is locking up. The next time this happens, open the bleeder screw on the caliper or loosen the steel lines at the master cylinder to see if it releases. If it does, we have to figure out what is trapping the brake fluid. If the caliper doesn't release that way, it could just be the caliper itself that needs to be replaced. Normally both front ones are replaced at the same time to maintain even braking.