[claud_face]

Hi guys,


I have a new central heating/cooling system installed and seem to have an issue here.

Over the winter I had no problems. Everything functioned properly.

Today I went to turn the A/C on and every 5 minutes the condenser turns off while the blower continues to blow air. Also the thermostat is still set to cool as it is far off its desired temp.

The only test I have done so far is check the voltage on the thermostat wire at the A/C and it is 24V. However, when the A/C condenser turns off it goes to 0V which leads me to believe the problem is at furnace/thermostat? If it was 24V the entire time I would think it may have something to do with the contactor or capacitor but if its showing zero volts it makes sense it is not functioning.

Also after 5 minutes it just automatically starts up again. It goes like this back and fourth non stop. Not sure what could be going on.

Any help?

Thanks!!

 

[BayouRunner]

Could be a quite a few things. Could be a low or high pressure cutoff. Could be a two stage thermostat and it's not wired correctly. When the condenser goes off see if you still have twenty four volts at the two wires that go to the condenser from the house. If the voltage goes off there then I would be looking at then thermostat

 

[supers05]

Let's start with the model and make of the condenser unit. A picture of the wiring will help us guide you.

My guess is that it's a low pressure cutout. It could be a high pressure cutout but often they are manual reset.

Cheers!

 

[beenthere]

Do you have a condensate pump, or float switch that may be shutting the A/C off because of a restricted drain.

 

[Phases]

Long shot but... I found out the hard way that even tho it claims it doesnt.. nest thermostat needs common wire. We had problems like this till I realized that. I used the extra 2 stage heat or 2 stage cool wire for it depending on season until I could get around to running new wire..

 

[jbfan]

Why not call the company that installed back out to troubleshoot it?

 

[claud_face]

Thanks guys.

I have a nest and yes I installed a common wire.

As bayourunner mentioned I did check the voltage and when it turns off the thermostat wires show 0volts. Then it turns back on because it shoots to 24volts.

Then off again on again and repeat. Made me wonder what would cause it to be 0 volts on the thermostat wire. It should be 24V because the thermostat still shows cooling while trying to reach that target temp.

Model is an American Standard 4A7A3042D1000NA

 

[supers05]

The literature that comes up for that model number shows a premium model with a main control board. Does yours have one? That board should have a fault code led that'll tell you what's wrong.

Cheers!

 

[supers05]

It appears that your unit is also covered under the service bulletin un-svb021e. (serial numbers 13401****F to 14445****F 13401****H to 14445****H 13401****L to 14445****L )
"Addition of Oil Additive CHM01005"

Meaning that for systems with a txv, they are having problems with the oil becoming to viscous, clogging everything including the txv. Depending on when yours was installed, it might have already had it added. If it wasn't, this is a good reason for low suction pressures. (causing the low pressure switch to trip, shutting off the compressor)

Even if this isn't the issue, and I'm fairly certain it's not. Ask the installing company if they added this additive. It'll extend the life of the system.

Cheers!

 

[smithwatson7]

Yes it might be due to Voltage variation. Its better to get the connection re-checked by the team which installed your AC.

Regards,
Smith,