DIYbanter - View Single Post

wrote:
Mikepier wrote:
The blower is suppose to come on at the same time with the compressor.
There is nothing wrong with that.
It could be that the furnace schematic was showing you the 30 second
delay for the heat. During heat mode, when the burners ignite, the
blower does not come on for 30-45 seconds until the heat exchanger is
at the proper temperature. Perhaps your old T-stat was wired wrong and
now the new T-stat is wired correctly.

The furnaces I've seen have all had the blower come on right away,
however with trying to make everything more energy efficient, I
wouldn't be surprised to see newer ones where the blower is delayed 30
secs. It will take that long for the coils to get cool, so saving 30
secs of run time helps.

It's possible some parameter is set wrong in the thermostat. I'd
review all the programming settings in the thermostat. That's a great
and versatile thermostat, but it does have a zillion settings and
parameters. Next, I'd try doing a master reset on the thermostat,
then reprogramming. If that doesn't work, I'd call HW support.

Gentlemen,
Thanks for the response. I am sure that there is a 30 second on and
off blower delay for the AC. The heat blower delay is adjustable via
switches on the unit, but no such adjustment for the AC. It says on
the schematic, 30 second delay on and off for the blower in AC mode.

But now, get a load of this. Last night this was bothering me to no
end. I certainly don't want to ruin a perfectly good AC system. On
the thermostat, I disconnected the FAN relay wire (G). On the
thermostat, if I try to put the fan on by itself, it doesn't go on.

BUT, if the unit calls for AC with the fan in automatic mode, when I
hear the thermostat relay 'click', 30 seconds later the fan goes on.
Working as I remember it AND how it was working with my old thermostat.

So...I've looked over all the settings for the thermostat, and there is
a setting of:
FAN OPERATION: T
0 = Conventional applications where equipment controls fan operation in
heat mode
1 = Heat pump or electric heat applications where thermostat controls
fan operation in heat mode

But, as you see this has nothing to do with ac...

So, what it looks like to me is when the thermostat calls for AC, it
(the thermostat) is not supposed to energize the fan relay, as the fan
will automatically be kicked on when the unit calls for AC.

What do you think?