I love my 2004 MDX but we are having the hottest summer ever and my a/c unit suddenly only works part time. Refilled coolant but still doesn't work. Worked yesterday part time, but not at all today. Could it be the on/off button not working? Hoping it's nothing too expensive to fix. Am taking it in next week for the last 2 recall fixes at the dealer so guess I could have them fix it. Would you recommend dealer or outside repair?