The blower on my Amana/Goodman unit started to shut itself off intermittently, despite fan being set to "on" at all times on the t-stat.
You can hear the 'clicking' from the board as it tries to start the fan, but it is not successful.
However, if the AC is turned lower, the AC starts and the blower starts up again, and stays on after the AC has stopped (once temp is achieved).
This problem happenned VERY seldom at first, but I placed a service call to get it looked at, as it is such a new furnace.
On the first service call the fan had stopped to they "saw" it first-hand (the clicking and not re-starting). They couldn't figure out the problem exactly (tested t-stat as well). They placed an order for a new circuit board.
On the second service call, the tech replacd the board, but left all the dip switches in the factory defaults, which led to far too high a CFM setting. This did not fix the blower issue either, as it shut itself off 2 days later. I restarted it by activating the AC, and then again it shut off 2 days later. The next day it cycled through start/stop/start/stop every 30 seconds for about 5 minutes, and then eventually stayed on. The problem seems to be getting worse.
Given that the service tech left the board at the factory defaults, I'm not eactly all that confident in their ability to fix this issue. I was able to set the dip switches myself to the correct settings as per the initial installation 2 years ago.
On the 3rd service call the blower hadn't shut off, and the tech still was stumped. He also said that the new circuit board didn't appear to have switches to adjust the blower speed. I'm just a homeowner, and with some research and reading the manuals I was able to fugre it out myself.... so again, not a lot of confidence in these techs. He ordered a new blower motor, which has yet to be installed.
It feels like these techs are just guessing, and in the meantime my 2 year old furnace is being filled with replacement parts, which doesn't seem "ideal".
Can anyone offer a suggestion for why the fan would randomly shut itself off, but seem ok restarting when the AC kicks in?