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View Full Version : indoor fan operation in YORK air handler



frozenpal2010
22-07-2010, 08:27 PM
Dear fellows:

Actually, my regular field of work is commercial refrigeration. But there is this problem with a new YORK central two stage split system that is puzzling me.
The model of the air handler is NC120. The model of the condensing unit is YC120 (cooling only). They are both new equipment, using R-410A.
The situation goes like this: the air handler fan starts and stops together with the first stage of cooling, no matter how is the fan switch located at the room thermostat (on or auto).
Cycling indoor fan operation is not always recommended, and I canīt force the operation to continuous. I have checked the thermostat fan switch and is mechanically ok.
I thought that the problem was in the control wiring. I checked the wiring: there are five terminals R, Y1,Y2,G and C, going from the electronic board at the condenser to the same points at the thermostat. Nothing wrong here.
Then I took some time to review the wiring diagram pasted at the condenser side panel, and I found something interesting: the three relays (Y1, BR1, M1) that send the 24 volt signal to the first stage liquid line solenoid valve, indoor blower contactor, and first stage compressor contactor respectively, are all connected in parallel. This means that they work together as one: either on or off.
Does this mean that this system is designed to work only in cycling indoor fan mode? Have any of you faced this situation before ? Is there any factory recommended re-wiring that might allow me to set the indoor fan to work continuously?
Any inputs welcomed.