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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8688
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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580Dxx060 has no indoor fan operation. This unit has an IFC

Customer Question

Bryant 580Dxx060 has no indoor fan operation. This unit has an IFC and a 3 phase fan motor. I have power to the Green that turns to white that is connected to the control board "G". If I power the IFO terminal, the fan operates. I have replaced the LH33WPOO3A board and condition still exists. The diagrams do not show board internal operation. I have checked limits. Now I'm stuck with zero ideas.. Please help
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


If you can use the paper clip icon just above at the right end of the tool bar to send me a close up, well focused, well lit photo of the wiring diagram glued inside the blower door, I can mark it up with trouble shooting directions.


Customer: replied 1 year ago.
This diagram is showing the option of the 3 phase motor. I have currently jumped the green to IFO on the units thermostat connection board. This is bypassing whatever problem that is causing the indoor fan contactor to fail from energizing
Expert:  Phil replied 1 year ago.


also check for 230v across all combinations of L1,L2 and L3 at the disconnect switch.

Tell me if anything else runs, and if any error code LED's are lit.

We can go from there.

Customer: replied 1 year ago.
No error codes. The 3 phase compressor works. Like I've said, I've jumpered the Green to IFO to supply 24v to the IFC and the indoor fan runs. I've bypassed the problem. Just don't know why I don't have power to the IFC thru the board
Expert:  Phil replied 1 year ago.

Hello again,

Set the thermostat on cooling, and down to 60F, then I need you to jumper Red to G on the thermostat terminal... if the blower runs then its a thermostat problem.

Repeat the test but this time set the thermostat on FAN ON, and if the fan does not run, jumper Red to G and if the indoor blower runs, you have confirmed that its a thermostat problem.


Customer: replied 1 year ago.
I have power to Green. I'm jumping Green to IFO to bypass the control board. Looking at the wire diagram it seems the 24v to the IFC comes from the IFO terminal.
Expert:  Phil replied 1 year ago.

Hello again,

With AC current in these situations a digital volt meter can give you a false voltage read (ghost read) due to feed back through the rest of the system...

(this is not true with DC circuits, this is a source of confusion for people used to trouble shooting DC systems such as with cars etc).

There is a 50/50 chance that you have actual 24vac power available at G and not just a ghost read... by doing the tests prescribed we can eliminate or confirm that. Without that jumper test, and the tests prescribed earlier we are guessing, especially with that particular wiring diagram.

I will opt out for now, so that other of our experts here can see your question...I will still be notified of your responses though, and will resume trouble shooting this with you if you like.

Customer: replied 1 year ago.
I will do the thermostat test as you've required. But, earlier I mentioned that the Green from the thermostat is powering the indoor fan relay by way of a bypass I did on the units thermostat connection board. The current problem is the board will not operate the indoor fan relay without running Green 24vac to the IFC terminal via the IFO terminal where I have the jumper connected currently.