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Discussion Starter · #1 ·
Once temp drops to the desired setting, the AC turns off, but the fan keeps running. I know the fan might run for a little bit after AC goes off, but that's not it. My thermostat says 'No equipment running'.

My system is on Auto. When I switch between Fan Auto/On on my thermostat, I can hear what I think is a relay clicking for both Off(auto)/On. Usually, around the third time I switch from On->Auto, the fan goes off.

I recently replaced an old thermostat with ecobee3. I didn't have a 'C' wire, so I think the 'G', or fan, wire is serving that function now.

Is this a bad relay or did I mess up my ecobee install?

I should note that sometimes the fan turns off on its own in a timely fashion.
 

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disconnect the g wire from the ecobee and see if the fan stops.

if you used the g as common it wouldn't do anything, switching from auto to on.

the relay being used for continuous fan may be different from the one used for a/c.

what's the brand/model of the air handler or furnace?
 

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Discussion Starter · #3 ·
When I disconnect the ecobee, the fan keeps running. When I turn the power off and then on, the fan start up as well. I have to switch the power off/on a couple of times for the fan not to start... There's something magical here about number three... I don't know if it's the capacitor that has the juice to jump start it twice but not trice?

Not sure what the brand of the air handler is. I googled a few numbers from the sticker on the air handler, and I got a hit on the:
* York Central Air Conditioner Model F1SA018R06A
* York LR49182c (I'm guessing that's the air handler)
 

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couldn't find any literature on the air handler so have no idea what controls it has.

what happens if you disconnect g and y right after a cooling cycle at the stat?

(i'm wondering if some current leakage from y through t-stat is wreaking havock. t-stats like ecobee and nest don't use mechanical relays to my knowledge)


could be a relay sticking or something else. weird.
 

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Discussion Starter · #5 ·
It's a bit difficult to disconnect just these two wire. The wires are connected to the wall plate, and the t-stat just plugs into it. Kind of like a laptop into a docking station.

Anyway, I undocked the t-stat from the wall plate. Effectively disconnecting all wires. I tried it 4 times:
Attempt 1: The fan stopped
Attempt 2: The fan kept going
Attempt 3: The fan stopped
Attempt 4: The fan kept going.

In all cases AC stopped I think. It's 3 floors up, so it's hard to tell, but the air coming out of the ducts was not as cold as I'd expect with AC on.

I guess for attempt 2 & 4 I allowed the fan to reach full speed. In attempt 1 & 3 I unplugged the t-stat as soon as I heard the fan starting up.
 

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Discussion Starter · #6 ·
I decided to take the ecobee out of the picture. I tried controlling the fan by touching Green and Red wires. Same result.

When I touch G & R wires the fan starts. When I separate the two wires, the results are variable. Sometimes the fan stops, sometimes it does not.

When the fan does not turn off after separating the two wires, repeatedly touching the wires will eventually turn the fan off. Sometimes it takes 3 tries, sometimes 5 or 6, but eventually the fan goes off.

I made a video to better illustrate the problem :smile: -

What is wrong with this fan?
 

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Discussion Starter · #8 ·
I did some googling, and it seems like the same relay is at least $50 + shipping. I'm guessing it's because it's no longer produced. I see newer blower fan relays are way cheaper, so I'm wondering if I can just use a new one.

Given the specs below, what are acceptable deviations? I'm assuming voltages and frequency have to be the same? FLA and LRA have to be the same or higher?
For example, is this relay acceptable: https://www.grainger.com/product/GRAINGER-APPROVED-Relay-5MMA2?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/5MMA7_AS01?$smthumb$

My original relay specs:
WHITE-RODGERS/RBM
134-20103-301Q
14FLA 84LRA 125VAC
7FLA 42LRA 277VAC
25A RES. 277VAC
COIL 24V 50/60HZ
024-24984-000
 

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to verify 100% it's the relay, when the fan stays/sticks on, shut power, disconnect wires, and ohm out the normally open and closed contacts. (if it has closed contacts)

good to be completely sure rather than changing good parts.





You have to be able to mount it and it has to be the same type - for example, single pole double throw.

The coil voltage and frequency has to be right on.

you're right about the amperages.

the voltage being switched has to be the same or higher.

you don't have to use the same relay model.

link copied, doesn't work for me.

white rogers is made by emerson, so go on their website and see if you can cross reference it.
 
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