Unit will start up with switch in off position. Will run for about twenty seconds and then shuts off. Does this intermittently. May go for hours or may go for only 25 or 30 minutes before starting again but still only runs about 20 seconds before shutting off. Seems to run OK when in a continuous heat mode. Due to cost of control board , customer says they can live with it. They will just cut it off at the breaker panel. Any harm in running it this way?