my fire place model 23ef022gra blows the hot air only for 5minutes then the fan goes off the logs are still lit but on hot air. I tried unplugging for 10 min pluged back in reset the thermostat but no luck the fan stops after 5 min. I pechased this on 11/12/10 never had a problem until now. Can you help me ? I also have another unit works great thanks. Hector