Problem with fan only operation

Problems related to residential installations.

Problem with fan only operation

Postby mwb » Fri Oct 12, 2012 1:20 pm

I have a two story, two zone system, with a Ruud heat pump. A/C works fine, cooling and blowing when called for by t-stat settings. However, neither t-stat will operate the blower in 'fan only' mode. That is, the only way to have the fan blowing is to have either heat or a/c driving it. Both t-stats have the usual switch, labeled in the usual way (fan on/auto), but neither switch causes anything to happen.
By the way, this house is brand-new construction. The contractor doesn't have a clue. Says it must have something to do with the fact that we have two zones, but only one heat pump unit. Doesn't understand why someone might want to operate the fan by itself.
Anybody ever hear of this? I know I can keep raising cain with the builder, but I thought if I could point him in the right direction, it help me get this fixed.
Thanks.
mwb
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- Problem with fan only operation

Postby Freon » Fri Oct 12, 2012 3:23 pm

First check that the wire connected to the G terminal at the thermostat is the same color/wire as is connected to the G terminal at the air handler. If this is a programmable thermostat check that the Fan On isn't governed by intermittent operation.

If that all checks out, remove the cover to the thermostat and with the Fan set to On, CAREFULLY measure the AC voltage between the G and C terminals. You should get 24. Do the same at the air handler... you should get 24 volts AC also.

If you get 24 volts AC between G and C at the air handler, then some setting on the control board may be amiss.
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- Problem with fan only operation

Postby mwb » Sat Oct 13, 2012 9:23 am

Thanks for the suggestions.
I guess I'm also asking if this situation could be considered 'normal' for any standard installation. It seems like my contractor and his HVAC sub just don't want to figure it out. Am I being unreasonable in insisting that they correct this?
mwb
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- Problem with fan only operation

Postby Freon » Sun Oct 14, 2012 3:53 pm

If it's new and doesn't work as promised, you are NOT being unreasonable to have what you paid good money for working as promised.

If you have any final payments due, withhold them until it works properly. This isn't rocket science and could be a defective product that the installer needs to replace under the manufacturer's warranty. They are lazy... press them to do the right thing. Maybe a suggestion of letter to the BBB will motivate their self-interest.
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- Problem with fan only operation

Postby mwb » Fri Oct 26, 2012 7:46 am

Thanks for all the suggestions.
Turns out that the fan itself was wired incorrectly at the factory. It took them a while to figure that out, but they're coming today to replace the whole fan assembly.
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