HVAC Not Cooling, sometimes.

Without being there, I'm not getting any big ideas what might be wrong. My first thought was dusty condenser, but that's unlikely on a unit less than a year old.

Be interesting, see what the tech finds. Please follow up on this list, we can learn from you. Thank you.

wonder if the air filter is clogged?

What if you lost power for 1/2 second from a squirrel playing on the line of a train hitting a utility tower? Maybe the noise you heard was not the condenser fan but the compressor trying to resume operation against too much pressure. In a couple of minutes, a protection device shut off the compressor because of heat or pressure.

Does it have a restart lockout timer to prevent the compressor from short cycling? If not, it may have been liquid slugged and overheated. Letting it settle for a while got it working again and I hope you didn't really hurt anything.

It seemed like something like that might have happened BUT the noise and vibration started exactly when the A/C started. The noise I hard was probably from the compressor trying to start after being off for at least a couple of hours. I had set the thermostat up a couple of degrees in the morning because it was a nice day and we opened the doors. In the afternoon, it got hot so I closed the doors and lowered the thermostat and that's when the lights blinked at the same time as the compressor tried to start.

The thermostat has a lockout timer so you can't turn it on and then off and then right back on. I think the timer prevents a restart from happening for 3-5 minutes.

I have a Dust Eater filter that was back washed about 10 days ago. In any event, the Condensing Unit (probably the compressor) had a problem as soon as it started so I don't think the filter came into play.

I've had my refrigerator compressor overheat and shut off because of a power interruption, but the interruption occurred after it was running.

I don't know how many amps it take to trip a momentary interrupter on a power line. Maybe there happened to be an exceptional load on the line at that instant. Your compressor was enough to trip the power company's device, and your lights flickered.

In our neighborhood, we have drop down fuses that will disconnect the transformer if there is a high current problem. Then you have to call the utility to come out and close the fuse. No momentary interrupters that I know of unless there is something at the sub-station (2 miles from my house) that does a momentary interruption.

If they are switching power around the grid, you can get little "blinks" of the lights. (up to a couple seconds). That is why the UPS is such a popular thing.

This says a fuse must be replaced if it disconnects the circuit. It says the small circuit breaker on a distribution lines is a recloser.

When a pecan limb fell onto bare distribution wires behind my house, lights in the neighborhood blinked. I imagine that was the recloser across the street. If the limb had kept the lines pressed together, the lever on the recloser would have popped down and a guy with a long pole would have had to come to reset it.

Reclosers usually reset themselves (AKA automatic recloser). That is why you may see it come on a couple times before it stays off.

We have that at least once a month on one of the phases. Drops out the one AC, TV box will have to reboot. PITA, but no damage.

Here is what the tech said:

While it is possible that there was a temporary power failure that caused all of the compressor racket, the more likely problem was a stuck TXV valve in the A coil as described in the links below.

Starting in 2014, Copeland, who makes the compressor, started adding a rust inhibitor to the compressor. The inhibitor had the consequence of occasionally freezing the TXV valve thus preventing any circulation in the system. When the TXV valve freezes, it causes the compressor to struggle and finally shut down.

The solution is to add a cleaning fluid of some kind (A/C Re-New ?) to the system and run it for 48 hours to get rid of the anti rust inhibitor and free up the TXV valve. If the TXV valve is still frozen, then the TXV valve has to be replaced.

The tech said keep an eye on it and if it happens again, they will come out and flush the system and replace the TXV valve if that is necessary.

Here are some relevant links:

Explanation of Problem

Copeland Lawsuit

Youtube Video How to Fix. Includes about about 140 comments

Does it reclose, or do you call the man with the pole?

I have to call the man with the pole. When I call, I tell that I am out there with my tree trimmer and is it okay if I do it myself. Of course, they scream at me No! No! and send their own pole guy out IMMEDIATELY!!

Drops and goes back by itself. Just goes out long enough to cause things to stop.

Sounds like a tech who keeps up to date a lot more than I do. Please keep his company number, and reccomend him to all your friends. Good person to have on the rolodex.

And, thank you for sharing with us.

- . Christopher A. Young learn more about Jesus .

I was mistaken. In my neighborhood, the power-company guy brings one of the Flying Wallendas, who walk on only one wire at a time. I thought that was a Polish name, but it's German.