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8/29/2020 7:27 AM
Edited Date/Time: 8/29/2020 7:56 AM

Need some advice. So I have a newer Amana unit, replaced the entire furnace and AC unit roughly 3 years ago. My problem is I have my temp set to 71° and fan set to on. The fan doesn’t run constantly like it’s supposed to, and sometimes the temp will stay above the target of 71° for a while before the unit will kick on and cool it back down. I’m pretty sure once it goes 2° above target it’s supposed to kick on, but it doesn’t. It’s just running really intermittently with no rhyme or reason for why it’s doing what it’s doing. Like I said, the fan is set to on, and I’ll get nothing out of the vents, then randomly I’ll get some air blowing and later nothing. I’ve switched to heat and it has the same symptoms. So the fan and AC work, they’re just not doing what they’re programmed to do. Does this sound like thermostat issue? I’m thinking it’s a bad thermostat, but want to confirm before I run out and buy a new one. Thanks!

EDIT: Thermostat is an older Honeywell Wi-Fi thermostat from like 2013 or so.

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8/29/2020 1:52 PM
Edited Date/Time: 8/29/2020 2:53 PM

Swapped the thermostat for an ecobee 3 lite. Same problem. Runs for a few minutes then quits. Very sporadic. The AC and fan both work, so I don’t think it’s a furnace issue. The random turning on/off has to be a thermostat issue.

EDIT: ecobee app now showing the thermostat is offline. Seems the thermostat is losing power somewhere. It’s powered by the furnace. I know the connection at the thermostat is good since I just replaced it, guess I’ll go check the wire at the furnace.

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8/29/2020 4:04 PM

Has it done this since you put the new unit in or was it working right at one time?

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8/29/2020 4:27 PM
Edited Date/Time: 8/29/2020 4:40 PM

jgmxdad251 wrote:

Has it done this since you put the new unit in or was it working right at one time?

Worked perfect the last 3 years up until about Wednesday, that’s when I noticed the fan wasn’t running while it was set to ON. Before I found some time to dive into it, it was working again. Then it quit again. It’s been working on and off the past couple days.

I’m at a birthday party right now, but just checked my ecobee app and it’s back online, fan and AC both running. It was offline and nothing was running when I left the house.

UPDATE: 9 minutes after I posted this and it’s offline again. So the unit maybe ran 15min or so, then kicked back off. Current temp is 78° with a target temp of 71°.

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8/29/2020 4:45 PM
Edited Date/Time: 8/29/2020 4:59 PM

I would dm motogrady, pretty sure he’s a service guy. I install commercial HVAC, not that good at service. First thing I would do is take your panel off at furnace. Push your Safety switch that the door holds closed. It probably has a digital box that will flash and show one number at a time, it will give you a numerical code. Then look on underside of panel you took off and it will have a legend for the codes. Good place to start if there’s a problem.

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8/29/2020 5:34 PM

Thanks! Just got home, gonna look into it now.

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8/29/2020 5:55 PM
Edited Date/Time: 8/29/2020 6:03 PM

Ok, so no digital code, but it does have a red led that’s on. The legend says “Steady On = Normal Operation.” So everything is ok there. Thermostat still offline.

I’m gonna turn the power off to it and check the wiring for a loose connection.

UPDATE: We’ll as I was typing this, still had the cover off, the damn thing just fires up and starts cooling. All I did was pull the cover and check the light. Didn’t even wiggle any wires yet. Thermostat back online now. WTF is going on? laughing

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8/29/2020 6:06 PM
Edited Date/Time: 8/29/2020 6:56 PM

And it’s back off. So it ran however long between my edit above and this post.

Update: Wiring all seems tight, although I noticed the original wiring from the furnace to the thermostat seemed a bit brittle compared to the original wires. It appears I may have a wiring problem between the furnace and thermostat now. Ugh.

Update 2: Safe-T-Switch on the furnace was full of water. Drain pipe had a clog. I guess once the water drained enough the unit would kick back on, then fill up, trip the switch and kick it back off. Sucked all the water out of the switch, left the switch out to dry a bit, and hooked a shopvac to the Y in the drain pipe to try and suck out the clog. Working for now, we’ll see if it clogs back up.

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8/29/2020 7:06 PM

That’s what I was going to tell you next. At least you know it works.

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8/29/2020 7:08 PM

Should be fine after you fix the clog.

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8/29/2020 7:17 PM

Shouldn’t have debris in there. You should see if there’s an inspection plate on the coil and check for dirt. Make sure you change your filter regularly and that it seats good.

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8/29/2020 7:31 PM
Edited Date/Time: 8/29/2020 7:36 PM

There are some tablets you can put in your pan to discourage growth of organics that can clog lines.

Also, how old and what state you're in matters. Can you just puke it out on the lawn, or does it need to go to drain .

The lawn? No big deal. Into drain, like a rarely used sink, in an extra bath? Shit grows.

But I'm going with "there's your problem ".

It was doing you a favor, overflowing pans can cause a lot of damage depending upon where the unit is.

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Go for it! Don't let a little thing like fear, or common sense hold you back.

8/29/2020 8:18 PM
Edited Date/Time: 8/29/2020 8:20 PM

@jgmxdad251, I change the filters monthly, plus there’s a really big filter on the furnace that gets changed annually. I’ll check the coil for dirt. It’s in the garage which doesn’t get too dusty, so it shouldn’t be that dirty but we’ll see. I really appreciate your help!

@SEEMEFIRST, Yeah the water wasn’t in the drain pan on the bottom of the unit, that was the first thing I checked. Drain pan was dry. There’s another safety switch I didn’t know about up higher on the furnace by the drain pipe. Still not sure if I got the clog by vacuuming, but I could tell it sucked something out. Maybe just water. I wish they would’ve installed some threaded couplings where I could remove the PVC pipe and clean it out, but it’s all glued together. Either way you’re right, it did me a huge favor by not just dumping water all over the garage.

One things for certain, everyone in my house takes the AC for granted until the moment they don’t have it. laughing

Busy day, gonna go watch today’s races on Gold now. I haven’t dared venture to Moto-Related yet. lol

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8/30/2020 8:19 AM

If you change the filter once a month, then the coil should be clean. I wouldn’t bother checking.

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8/31/2020 7:43 AM

When you have time, go ahead and modify the primary condensate line with a removable cap so that you can pour some bleach in it once a month. I do it when I change my filter. That will help keep algae and other crap from growing and causing a clog.

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8/31/2020 8:15 AM
Edited Date/Time: 8/31/2020 8:34 AM

BMR179 wrote:

When you have time, go ahead and modify the primary condensate line with a removable cap so that you can pour some bleach in it once a month. I do it when I change my filter. That will help keep algae and other crap from growing and causing a clog.

Yeah I need to do that. It’s easily accessible, so I’ll just cut the PVC and install a T with a cap and I should be good to go. It has a Y pipe coming off the PVC further down the line, but I think a T up near the furnace would be better.

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