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# No fan

#1
06-10-10, 01:31 AM
Member
Join Date: Jun 2010
Posts: 3
No fan

The ahac guy came changed the coil and the outside unit. Actually he put a 2.5 tons instead of a 2, I wonder if it is right.

Anyway the problem is that when I put on fan alone the thermostat nothing spin.

#2
06-10-10, 05:34 AM
Member
Join Date: May 2008
Location: Wisconsin USA
Posts: 713
Hope the system is not oversized now for the ductwork

I hope the system is not oversized now, & the duct system could b undersized now, unless he adjusts the fan speed for a lower 360-cfm per ton of cooling.

That is 900-cfm instead of 1000-cfm of airflow.

That will result in a colder cooling cool & improved longer run cycles for increased humidity reduction...

The t-stat control wiring is not hooked up right for the fan switch to energize the fan relay.

Last edited by HVAC RETIRED; 06-10-10 at 05:39 AM. Reason: Fan switch Clarification...
#3
06-10-10, 01:55 PM
Member
Join Date: Jun 2010
Posts: 3
Originally Posted by HVAC RETIRED

The t-stat control wiring is not hooked up right for the fan switch to energize the fan relay.
Well I can't tell. Is there any mesurement I can do with my volt meter?

#4
06-10-10, 06:30 PM
Member
Join Date: May 2008
Location: Wisconsin USA
Posts: 713
Originally Posted by asterix
Well I can't tell. Is there any mesurement I can do with my volt meter?
Locate the blower motor fan relay & trace the small conductor that goes to the room t-stat, note its color coding, it's usually green. Yellow usually goes to the condenser control contactor.

It has to be connected to get voltage usually from the red conductor that comes from the + side of the low voltage transformer, the manual t-stat switch merely completes the voltage path to the blower relay.

Therefore, TR + feeds one side of switch (SW) & usually green wire to fan relay goes to other side of SW.