I am the perplexed owner of a Coleman Evcon DGAT075BDD that is experiencing an intermittent blower problem. Let me first say that the furnace works just fine when it's doing its job. It kicks on when the thermostat tells it, and it heats the house with no problem. The problem is that for the past 8 months or so, the blower (and not the burner) will randomly turn on when there is no cause for it to do so. It will then run for about 2 minutes while it blows room-temperature air around the house, and then it will shut off. There doesn't seem to be any rhyme or reason to when it turns on, either. I've seen it come on up to 4 times a day, or maybe just once a day. Sometimes the interval between these weird 2 minute blower cycles is hours, but I have also seen them occur almost back to back.
About 6 weeks ago, I got fed up with this behavior, and I called a repair person. He came out, did his diagnostics, and couldn't find any reason why the blower was operating intermittently. However, he did suggest that I might try replacing the 2 limit switches on the furnace (7990-359 & 7970-382). A couple weeks ago, I finally got around to replacing the 2 switches, but this changed absolutely nothing; the problem remains.
So, I'm coming to the experts
What should I try now?
