BIDDEFORD — Dr. Frank Kleeman has waited a long time to close the doors of the Biddeford Free Clinic. When he first opened it 22 years ago, he thought for sure there would only be a need to provide free medical care for uninsured Mainers for a few years. But with no major changes to the health care system until the 2010 Affordable Care Act, the number of patients who couldn’t afford a doctor held steady. For years, the clinic – the first of its kind in Maine – would open three nights a week, staffed by dozens of volunteers who diagnosed and treated acute and chronic illnesses, performed lab tests and filled prescriptions.