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AC condenser/fan refused to come on last night, but today works fine

8YY old Bryant central AC. Moderately used, just popped it on last night a nd I noticed even though the blower was running the condenser and fan outsi de weren't. Tried each of three zones, that didn't make a difference. So today I said what the hell, before I call the service guy I turned it on a gain, fired right up. Too chicken to run it for more than a few minutes.

We've only had it on like once or twice this year, what might make it behav e that way?

Reply to
noname
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and I noticed even though the blower was running the condenser and fan out side weren't. Tried each of three zones, that didn't make a difference. So today I said what the hell, before I call the service guy I turned it on again, fired right up. Too chicken to run it for more than a few minutes.

ave that way?

Ok tail between legs, for 9 years zone 3 only hasn't been turning on the AC unit because the thermostat was wired wrong! Compared the wiring to the o ther 2 zones and the yellow wire is connected to the wrong post (I think it is Y1 or something).

Gonna switch it over tomorrow when I have better lighting. I don't have to turn off the power do I ?

Reply to
noname

After switching your thermostat to Cool, it may wait several minutes before it will signal the compressor to turn on. That's a safety feature in some thermostats, to protect the compressor from being turned on too soon after being turned off.

If I were going to fool with thermostat wires, I'd first cut the power to the control unit so I wouldn't damage the compressor. (see above)

Reply to
J Burns

well it is clearly wired differently than the other two thermostats. How do I cut the power to the control unit is that the white box on the side of the furnance? Or should I just cut the power to the house?

Reply to
noname

In my breaker box, the breaker for the furnace/AC control is marked. (There's another breaker for power to the compressor.)

There's also a light switch beside the furnace, to shut off power to the control box and blower. If I remove the cover to the blower compartment on my furnace, I can see the control box. An LED glows if it has power.

If your thermostats let you switch on the blower without heating or cooling, you could use that to see if you switched off the right breaker.

Reply to
J Burns

Just turn off the furnace disconnect switch.

Reply to
clare

It's called the process of elimination. Turn your breakers off, one by one, until the power to the "white box on the side of the furnace" goes off.

And for the love of God, label your damn circuit breakers.

Reply to
bubba

It is very wise to turn off the power when working on wiring. Thermostats are typically

24 VAC, not enough to really be dangerous. But why risk damaging transformers, etc?
Reply to
Stormin Mormon

Many or most furnace have a switch on the side. Looks a lot like a light switch.

- . Christopher A. Young learn more about Jesus .

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Reply to
Stormin Mormon

HVAC techs the world around know who loves God, the moment we start a job. We go glance into the circuit box, and look for Sharpie marker.

Atheists and agnostics never label breakers.

Me, for example, I used three or four sharpies to dryness in my panel box, I love God so much. Wasn't sniffing solvent, honest!

- . Christopher A. Young learn more about Jesus .

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Reply to
Stormin Mormon

Ok fixed the wiring for the 3rd zone. No luck! It seems Zone 1 turns on the AC just fine. Zone 2 and 3 the condenser fan never starts spinning. I verified they are all wired the same to the thermostats. What next? Could this be the AC control unit? Any other debugging ideas?

Reply to
noname

I've never seen a multizone AC system, but I know they exist. They key question would be how are these 3 separate thermostats wired to the system? I would assume that they go into something other than the normal one thermostat input that most ACs would have. Would seem you need a controller of some kind before the AC unit to work dampers to make the air flow go to the zone/s that need it and not to the other zones. So, do the 3 thermostats feed into some zoning gizmo?

The other thing that makes no sense is that you're saying that with the non-working zones, the blower starts up in response to the thermostat, but not the outside condenser unit. I don't get that, unless some kind of zoning thing is somehow involved. Single zone AC, the thermostat connects to the controller on the air handler, which in turn has an output that closes the contactor in the condenser, turning it on. I think it all comes down to how this is wired and works, without a diagram etc, impossible to diagnose.

Reply to
trader_4

I believe a compressor can be wrecked if not enough registers are open in the house. Maybe the system wasn't designed to turn on the compressor with zone 2 or zone 3 only, because because neither has enough registers. There may be a diagram and explanation online for the OP's model.

Reply to
J Burns

and I noticed even though the blower was running the condenser and fan out side weren't. Tried each of three zones, that didn't make a difference. So today I said what the hell, before I call the service guy I turned it on again, fired right up. Too chicken to run it for more than a few minutes.

ave that way?

Find a handyman type neighbor.

Reply to
hrhofmann

I thought about that too. Like I said, I haven't seen a zoned central AC system. The fact that you could only reduce airflow so much with a typical system was a big problem. But now that there are many dual stage compressors available, I would think that may solve that problem. But IDK if they are doing that or not.

The essential problem here is what exactly are those thermostats hooked up to and how? Air handler/furnace directly with the zoning function built into the furnace? Never heard of that existing. Or are they wired to some zoning controller before the AH/furnace?

I just came up with a third possibility. That the system isn't really zoned at all. Those other two "zones" may just be thermostats wired in to turn on the fan only. Like the upstairs gets too hot, it turns on the system fan, to try to even out the temp. That would explain why it works like it works. That's my bet.

Reply to
trader_4

Sorry, can't think of anything from here. Wish I could be more help.

- . Christopher A. Young learn more about Jesus .

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Reply to
Stormin Mormon

I wouldn't have thought of that, but you are right. That does make sense given his symptoms.

Reply to
Pat

Since you've had it on so little, it feels neglected. Like plants do. You have to sing to it, or at least talk to it.

Reply to
micky

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