No fan


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Old 06-10-10, 01:31 AM
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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.
 
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Old 06-10-10, 05:34 AM
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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...
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Old 06-10-10, 01:55 PM
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Originally Posted by HVAC RETIRED View Post

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?
 
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Old 06-10-10, 06:30 PM
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Originally Posted by asterix View Post
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.
 
 

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