Delayed startup with the air conditioner

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firealarmveteran15
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Delayed startup with the air conditioner

Postby firealarmveteran15 » Thu Feb 01, 2018 9:58 pm

First off, I know it's not time to start using the AC just yet (I don't live in Florida or southern California), but I wanted to address this problem way ahead of time.

Back in the summer of 2016 (when this problem started), I seem to have noticed that the AC in my house would have a delayed start when it powers up.

Here's a rundown of what happens when a delay occurs. First, I'd hear a somewhat loud AC buzz, and then the air would start circulating from the ceiling vents scattered throughout the house. From my experience, the delay can be as short as ~5 seconds to about as long as 20 seconds or so; and in some cases, there's no delay at all.

Thankfully no damage was done by the AC in 2016. During the summer of 2017, the same thing happened, but, once again, no damage was done, thankfully.

But the delayed startup, especially the super long delay, makes me worry that it could start a fire at any moment. I say this because I saw a YouTube video of a building's fire alarm going off due to an air conditioner catching fire or something like that (I have the link to that video saved somewhere, but I'm too lazy to go and search for it) -- well, at least according to the description of that video.

Unfortunately, I have no idea how long that air conditioner has been installed. For all I know, it may have been installed when the house was originally built (meaning that it would have been in use for about 30 years since the house was built at around 1988 or so). Or it could have been a replacement. I've only been living in this house since sometime in 1997. But even with that in mind, my earliest memory of hearing that AC was sometime in the early 2000s.

Could it be time to replace the AC? Since it's too cold to use the AC, what can be done in the meantime?

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Re: Delayed startup with the air conditioner

Postby Retired STR-SG » Thu Feb 01, 2018 11:29 pm

I'll try to be helpful but there are no guarantees. I am not an electrician, but have a lot of electrical experience with fire alarm systems and clock systems. I also am not an HVAC tech but have an older house with an older HVAC system which I have repaired several times. If I called a repair person I would have gotten a good laugh and a visit from the sales department.

You only mention AC but not heat. Is the same system your heating too? Is this a split system with a furnace inside and an AC condenser outside? Or is it a single unit system with one big box outside? Gas heat with AC or a heat pump system?

My first impression is the loud AC buzz could be from a bad fan control relay or the fan itself. The fan motor bearings could be worn and binding or the start capacitor could be failing. If the system is used for heat is are there any strange noises when the fan starts for that? If you turn the fan on manually at the thermostat is there noise and a delay?

The other thing that comes to mind is an electrical problem in the house. Have you noticed that lights change brightness or appliances run faster or slower when something else turns on or off? Like the light in the living room gets dimmer when the refrigerator turns on. That would indicate a problem with the wiring which could cause low voltage at the furnace causing buzzing relay and delayed fan start.

Think about these questions and then we make the next step.

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Re: Delayed startup with the air conditioner

Postby firealarmveteran15 » Fri Feb 02, 2018 11:23 am

Retired STR-SG wrote:You only mention AC but not heat. Is the same system your heating too? Is this a split system with a furnace inside and an AC condenser outside? Or is it a single unit system with one big box outside? Gas heat with AC or a heat pump system?


I'm pretty sure that the furnace and the AC are separate.

The furnace is in a closed off room in the basement. Not sure if it's a heat pump system, but about three years ago at the time of posting this, the furnace was replaced. At the time of the furnace replacement, I heard something about a "new boiler" or something like that.

The AC unit, on the other hand, I believe, is placed in the attic, along with a condenser outside.

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Re: Delayed startup with the air conditioner

Postby Retired STR-SG » Fri Feb 02, 2018 12:14 pm

OK, sounds like you have completely separate systems. The term "new boiler" sounds like you have hot water or steam heating with radiators. Either the big stand up kind or the baseboard type. Then a separate AC system with an air handling unit in the attic.

The radiator system probably came with the house and the AC was added later.

The same questions apply about manually turning the fan on and the possible problems with relays, fan motor, capacitor, or voltage issues. With a completely separate system the issues would only be evident when using the AC.

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Re: Delayed startup with the air conditioner

Postby firealarmveteran15 » Fri Feb 02, 2018 4:13 pm

Retired STR-SG wrote:Have you noticed that lights change brightness or appliances run faster or slower when something else turns on or off?


To my knowledge, I only remember the former happening.

Retired STR-SG wrote:If you turn the fan on manually at the thermostat is there noise and a delay?


Not sure what you mean by "turn the fan on manually," but I had noticed a noise and a delay. Not sure if that answer helped, but my room is very close to the AC unit, and I usually take notice when it powers on (the "Fan" switch on the thermostat is always set to "Auto" all year round, and we don't ever change it to "On" if that's what you meant by "turn the fan on manually").

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Re: Delayed startup with the air conditioner

Postby Retired STR-SG » Fri Feb 02, 2018 4:34 pm

firealarmveteran15 wrote:
Retired STR-SG wrote:Have you noticed that lights change brightness or appliances run faster or slower when something else turns on or off?


To my knowledge, I only remember the former happening.

Retired STR-SG wrote:If you turn the fan on manually at the thermostat is there noise and a delay?


Not sure what you mean by "turn the fan on manually," but I had noticed a noise and a delay. Not sure if that answer helped, but my room is very close to the AC unit, and I usually take notice when it powers on (the "Fan" switch on the thermostat is always set to "Auto" all year round, and we don't ever change it to "On" if that's what you meant by "turn the fan on manually").

So you have noticed lights changing brightness when the AC starts. It is perfectly normal for there to be a flicker at the moment the AC turns on because the motor start surge can be up to 5 times the running current draw. Remember there is an inside AHU fan motor, the condenser fan motor, and the compressor turning on. That can be quite a load. However, if the brightness change lasts for as long as the AC is running that points to the voltage dropping because of the load which is not a good situation. May take an electrician to check the wiring.

Yes, the AUTO - ON fan switch on the thermostat is exactly what I am mean. If the fan is set to the ON position are there any strange noises or a delay? Keep in mind that only the inside fan will run so the load is much less than the entire AC system turning on. But it can be a clue in solving the mystery.

It may take waiting until AC season is here to really solve the problem. The entire system may have to be running to measure for voltage drop issues.

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Re: Delayed startup with the air conditioner

Postby firealarmveteran15 » Fri Feb 02, 2018 5:52 pm

Retired STR-SG wrote:Yes, the AUTO - ON fan switch on the thermostat is exactly what I am mean. If the fan is set to the ON position are there any strange noises or a delay?


To paraphrase what I've said in a previous post, the fan switch was never set to the ON position during either of the past two summers, so, as you said:
Retired STR-SG wrote:It may take waiting until AC season is here to really solve the problem. The entire system may have to be running to measure for voltage drop issues.


In the meantime, I'll forward a link (soon) to this post to my dad and see what he says. I talked to him about the issue before, but, to my knowledge, he hasn't done anything about it (probably because I only talked to him about it once).


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