Last Sunday was a scorcher and we had the hvac running all day. By the end of the day we noticed that the AC was no longer on, and the thermostats screen was black.

We have an American Standard YCC unit, and the thermostat is a Honeywell Prestige touchscreen.

We are first time homeowners, so we are not very familiar with these types of issues. We checked online for possible things to check before we call a specialist with our home warranty company.

So far, I popped off the thermostat to see if it had batteries, it does not. It only has a coin cell battery that the manual says is for saving the date and time.

I checked the home's breaker box, and they were all still in the on position. I turned off the 2 combined ones listed as AC for awhile and then back on... nothing.

I climbed on the roof and noticed the PVC condensation pipe that runs to the gutter fell off at one of its joints, so I used PVC cement to reattach it.

I replaced both fuses, one of which smelled burnt. Then I power cycled the AC breaker in the home's breaker box again, still nothing.

I feel so close, yet so far. Is there a separate breaker switch on the AC unit or in the attic I should also be looking for? I have not found one yet.

Are there any other easy fixes I could be missing? I'd hate to pay the home warranty fee for a specialist to come out for 5 min to just flip a switch somewhere.

 

Since your air handler is upstairs in your house the condensate system should be protected from overflow.

Do you have a condensate pump near your air handler ?
If not... go up to the air handler and look for small wiring connecting to a device on the PVC drain line. This would be a pan float switch and it may be detecting a full drain pan.

 

Thanks for the quick reply. Here is what's on the roof. I'm not sure if that's what you are looking for. If not I can check the attic and snap some more photos.

 

I thought you had an attic air handler. You have a rooftop packaged unit. That would not need an overflow float as it's on the roof. Nothing to flood.

In your second picture I see a gray box on the side of your unit. Do you have power company "on demand" load shedding capability ? That's where the power company can curtail your power use and save you money on lower rates.

Should be your unit. manual/trane/ycc10.pdf

Your next step is going to require a voltmeter to make voltage checks in the power supply and the transformer. Is this something you are comfortable doing ?

 

That box is where the 2 fuses are.

I don't own a voltmeter and to be honest electrical is out of my comfort zone. I guess I should be proud to have made it this far. I think it might be time to call the home warranty company and have them send an AC repair man. Hopefully it's nothing major. Thanks for the help!

 

Good news! The thermostat magically turned back on today, and the AC is pumping out cold air again.

Not really sure what to think of this though. I had the breakers off when I originally replaced the fuses, and turned them back on after. But since the thermostat didn't immediately come back on, I just shut off the breaker again.

This morning I turned the breakers back on in anticipation of the repair man visiting. 3 hours later the thermostat and AC came back on.

So i'm guessing the fuses were the cause and I didn't give it enough time to reboot...? 3 hours seems excessive to me. Any ideas?

 

I don't know what to think. I go on service calls continuously. I carry a meter with me and usually have most problems sorted in a few minutes.

That thermostat should have turned on as soon as the 24vac supply was restored. I have no idea why it was time delayed but I'd imagine the problem will be back.