Strange AC sequence

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Old 07-17-17, 11:05 AM
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Strange AC sequence

Lately I have noticed something strange with my home AC. I will hear the thermostat click and call cool air, then 3-4 minutes later the fan kicks on, then 3-4 minutes later the compressor kicks in.

I have never noticed this happening till as of late. Usually the thermostat clicks on, then the compressor and fan start up. So why is is there such a lag like this and is it normal?

Thanks Paul.
 
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Old 07-17-17, 11:32 AM
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Check the time delay (either in your T-stat or in the condenser.) Time delay usually delay the start up 3-5 minutes if you shut down and restart the unit too fast. but if not restart, then this is not normal.
 
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Old 07-17-17, 12:06 PM
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Resolved, hopefully. Not sure why I didn't try this to begin with. I killed power to it all and then turned it back on. Things are back to the normal sequence.
 
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Old 07-17-17, 12:30 PM
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****** NOT RESOLVED ******

Power cycle seemed to cause the next cycle to run as it should. However the cycle after that the same old thing happened. Thermostat clicks on for cool, 3-4 minutes later fan kicks on, then 3-4 minutes after that the compressor kicks on. Weird.

As a note - I am not changing the thermostat to get it to go on or off. It is cycling all on it's own.
 
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Old 07-17-17, 01:46 PM
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Cycling the power will reset the time delay. You need a voltmeter to trouble shoot this problem.
 
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Old 07-17-17, 02:07 PM
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I don't think there is a problem. It's normal for most stat to have a time delay built in to protect the compressor from short cycling. The delay usually only affects the compressor but yours may delay both.

Your condensor most likely also has a delay module accounting for the second delayed period.
 
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Old 07-17-17, 03:56 PM
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I swear it has NEVER worked like this in the past. It has always had a call for AC and everything kicked on.

Where is the time delay module at?

The fact that the blower kicks on first and blows warm air into the house for 3-4 minutes, that doesn't seem right at all. I know that the compressor kicks off when the temp is satisfied and the blower runs for a little longer after that, but not first.

I'm good with a volt meter as I work on repairing gas pool heaters in my day job.
 
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Old 07-17-17, 04:38 PM
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The Time Delay Relay, if one is present, is in the outside unit. You should have a wiring diagram on the inside of the outside unit cover. Check the wiring diagram to see if your unit has a TDR.
 
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Old 07-17-17, 07:31 PM
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I thought time delay controls both compressor and outside fan at the same time, but not sure why his fan was delayed 3 minutes and compressor was delayed 6 minutes.
 
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Old 07-17-17, 08:01 PM
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I can't recall any stat I've worked with that delayed the blower coming on.

But if his stat does delay the actual call for cooling.... the blower would come on in xx minutes and the condensor, if it had a TDR, would be an additional xx minutes.

If you wanted to confirm a stat problem..... take it off the wall. Combine or jumper the Y, R and G connections together at the same time. The blower should start immediately. Not sure what the condensor will do. That would depend on an internal TDR.
 
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Old 07-17-17, 10:02 PM
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When you said 3-4 minutes later, fan kicks on.......... Are you talking about the blower fan ? or outside condenser fan ??
 
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Old 07-18-17, 06:38 AM
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When I say blower fan, that is the blower on the inside unit.

The sequence is as such, the thermostat calls for cool, you hear it click, then 3-4 minutes later the fan/blower on the indoor unit starts up. Then 3-4 minutes after that the outside compressor/fan kicks in.

BTW, the unit can be off for hours and hours and the first time it calls for cool, it will act this way. If it were a delay, wouldn't it have already reset do to it being off, not in use, for many hours? My understanding for the delay is that if the unit tries to cycle on again too soon, that is when the delay comes into play. Maybe I'm wrong, I don't know.
 

Last edited by ps0303; 07-18-17 at 07:53 AM.
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Old 07-18-17, 09:16 AM
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UPDATE:

Decided to use the shop vac to clean out the drain line. Since then the unit has worked as it should. Thermostat calls for cool, both fan and compressor come on simultaneously.
 
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Old 07-18-17, 10:21 AM
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Sounds like a float switch issue, still does not make sense, but it is working anyway.
 
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Old 07-18-17, 10:47 AM
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Yes in the past if the drain line was full, the float switch would prevent the unit from coming on at all. Never seen it where it acted like this because of a full drain line.
 
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Old 07-18-17, 12:42 PM
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It sounds like the float switch may not have been wired in to the best location.
 
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