Trane Air Handler Fan Constantly Running

You need to troubleshoot with your meter.

I don't see anywhere where that is time delay

https://www.supplyhouse.com/Honeywell-R8222U1006-24-V-General-Purpose-Relay-with-DPST-N-O-switching?utm_source=google_ad&utm_medium=Shopping_Electrical&utm_campaign=Shopping_X_Electrical_X_SSC_New&utm_campaignid=22402706596&utm_adgroupid=175772922365&utm_targetid=pla-351130410450&utm_product_id=R8222U1006&utm_matchtype=&utm_keyword=&utm_adtype=pla&utm_category=Electrical&gad_source=1&gad_campaignid=22402706596&gbraid=0AAAAAD_WAyuNs_BDEuq5qaUy-c8WN4SkB&gclid=EAIaIQobChMI0tDcm_XljQMVHDIIBR0xYRAHEAQYASABEgJNhPD_BwE

I think those are just double terminals for the coil so that it can be used as a junction point too.

That one terminal looks burned, probably from the failing contacts. I'd replace the terminal on the wire that connects to that terminal too.

I suspect the plastic melted from the failing contact and held the armature in place although an ohmmeter would tell you really quick.

Is the black stuff on that terminal sooty, does it rub off on your finger? silver plated terminals can tarnish and look like that, but that looks burned rather than tarnished. If it is burned, it is because the contact is failing and has high resistance and is heating the terminal. A bad termination to the wire could do it too, but you can see in the picture of it connected that the wire isn't burned on that terminal.

then it isn't the relay, it is in whatever is driving the relay somewhere

what is "lvtb"? the fuse should be the only thing connected to one terminal of the transformer and everything should connect to the other side of the fuse. if the fuse were blown nothing would work.

@loamyroots11 said: "Ok so disconnecting either the white or red wires from the coil causes the fan to shut off. The fan continues to blow when the green coil wire is disconnected."

Then @mattmia2 said:

And I disagree. By removing the red or white wire you are breaking the 220 VAC to the motor, same as the relay contacts between post 1 and 3 would break the 220 VAC to the motor. So that means the there is continuity between the 1 and 3 NO contacts on the relay. If the relay coil is not powered, then there should be no continuity between 1 and 3 on the relay NO contacts.

On the chance that there is 24 Volts powering the relay coil, removing the green wire or the double gray wire from the coil spade connector should cause the relay contacts to change position from closed to open. Since removing the green wire did not change anything then that is pretty conclusive that the relay is defective.

@mattmia2, You can't go by that wiring diagram. The PCB time delay on the R8222 relay is missing. There is a green wire that comes from the thermostat LVTB connection connected to the Coil on the R8222. I don't see the red wire from the diagram in the actual picture. That R8222 relay has continuity from 1 to 3 the NO contact terminals when the relay coil is not powered. I could be wrong, but that is what I am seeing. What I am seeing is not original wiring from 20 years ago.

OOOPs. I was looking as the other air handler too long. The red and the green and the double common are all low voltage. That relay is probably working fine as you said Matt

On that air handler, that PCB was used to delay the fan on for about 30 to 60 seconds so the refrig coil was cold before blowing air thru the ductwork. then it kept the fan on for about 60 to 90 seconds after the call for cooling was satisfied in order to maximize that cooling energy left in the coil. This was the Deluxe or Premium coil back in the day. The PCB has nothing to do with the heating coil. Hydronic heating coils were not a consideration for air handler manufacturers back then. only electric heating coils were considered and those sequencer and timers were part of the heat kit based on the kW rating of that particular heat kit.

I'd just add a time delay off module to the heat relay (or use the RIB with time delay). The aquastat does the on delay by not turning the blower on until the coil is hot. You only need off delay if you want it.

This Hydronic coil air handler may be a different zone, but the concept is still the same. Operate the AC with the controls system that waere installed by the manufacturer to use as an air conditioner. The existing original relay is for Fan on and for Fan auto operation for cooling. the G terminal on the thermostat takes care of that function.

to make the fan operate for heating, someone added an aquastat and a heat relay to that air handler. Just like zone 6 in your other post, the heat relay is there to

1. Turn on the fan to blow heated air from the hydronic coil to the rooms
2. Turn on the circulator pump and boiler to send heat to the hydronic coil
3. Then the aquastat is there to keep the fan from blowing unheated air in the winter until the hot water coil gets hot water in it. then the aquastat will allow the fan to operate.

Every air handler will have a similar design. There may be different ways to wire the system but the principle will be the same.