The Joys of Home Ownership

[ctechbob]

Otherwise known as my crap weekend.

Just venting.

Came home from work Thursday and on the way to the bedroom I walk right past the thermostat, I noticed that it was running the Aux heat on the heatpump. Not too uncommon as it will run during defrost cycles.

Came home Friday morning and again, aux heat running, thinking that was odd that I would catch it running two days in a row, I pop into the thermostat app that tracks usage to find that in those two days, the Aux heat had run almost 14 hours each day. Meaning the heat pump was NOT running.

The system is under warranty, call the installer, and they came out to find out the compressor had locked out due to high pressure. Not uncommon (pressure switch failures happen quite a bit from what I've been able to find out), pressures were all within spec on his gauges. Needs a new high-pressure switch. In the meantime, keep an eye on it and power cycle it if it locks out again. They leave, everything is good-to-go. Works fine(ish) all Friday and Sat. Wake up Sunday morning and notice the house is colder than usual. Thermostat says the system is running, but nothing is. No fan, no aux heat, no compressor.

Looks like I'm getting a pressure switch, new blower, and new air handler controls. Hopefully the stuff is all available and they can do it this week before the weather turns to crap again.

Guess where it started acting up!!!

10/31 - 22 kw
11/1 - 90 kw
11/2 - 129 kw

Grrr.

 

[Wayne]

Will all the repairs be under warranty?

I had a home A/C compressor fail one time three (3) days before the warranty expired. Talk about lucky.

 

[ctechbob]

I think I have to cover labor, although I can't remember. I haven't had time to pull the docs. Pretty sure it was 1 year parts and labor, 5 years parts, and then 10 years parts if you registered the equipment, which I did when I had it installed in 2019.

Still better than footing the entire bill.

 

[ctechbob]

Semi-update. High pressure switch has been replaced, and some relay in the air handler as well. Still no blower motor, so with colder temps this weekend it looks like we'll be heating the bedrooms with space heaters. Of course, we still won't know for sure if the HP switch was the problem until we can get the unit to cycle several times, and can't do that till the air handler is working.

The fun continues.

 

[MSCH]

Semi-update. High pressure switch has been replaced, and some relay in the air handler as well. Still no blower motor, so with colder temps this weekend it looks like we'll be heating the bedrooms with space heaters. Of course, we still won't know for sure if the HP switch was the problem until we can get the unit to cycle several times, and can't do that till the air handler is working.

The fun continues.

you would think the blower motor fan should work no matter what.. unless it has a capacitor that starts multiple electrical devices at the same time.

 

[ctechbob]

you would think the blower motor fan should work no matter what.. unless it has a capacitor that starts multiple electrical devices at the same time.

Well, it is a newer style constant torque multi speed motor, so it isn't just send power to it and it goes.

The Difference Between Variable Speed and X13 Motors - HVAC School

First, let's cover the basics. X13 is a brand name for the Regal Beloit/Genteq brand of constant torque motors; there are other manufacturers that make them, but the term “X13” has become pretty much synonymous with the fractional horsepower HVAC constant torque motor. Also, this article is...

hvacrschool.com

It really has me thinking that the blower might have been the problem all along. If the compressor is running and the blower isn't, then the pressures would shoot to the roof and lock out the compressor.

However.....

On the other hand, the blower was usually working with the emergency heat strips. I don't know if the fan kicks into a different mode when that happens or not. I haven't looked much into it since the HVAC company is handling it all under warranty. I could probably get up to speed and figure it out, but I don't have the time lately to learn something new.

I do know that the blower wasn't running this last trip with the system commanded to heat. It also didn't work when I commanded the fan to on without the heat running. I do know that the signal was getting up there, I at least checked that when I was waiting on the HVAC guys, so it isn't a thermostat or wiring problem, all the signals are going where they're supposed to.

 

[MSCH]

Well, it is a newer style constant torque multi speed motor, so it isn't just send power to it and it goes.

The Difference Between Variable Speed and X13 Motors - HVAC School

First, let's cover the basics. X13 is a brand name for the Regal Beloit/Genteq brand of constant torque motors; there are other manufacturers that make them, but the term “X13” has become pretty much synonymous with the fractional horsepower HVAC constant torque motor. Also, this article is...

hvacrschool.com

It really has me thinking that the blower might have been the problem all along. If the compressor is running and the blower isn't, then the pressures would shoot to the roof and lock out the compressor.

However.....

On the other hand, the blower was usually working with the emergency heat strips. I don't know if the fan kicks into a different mode when that happens or not. I haven't looked much into it since the HVAC company is handling it all under warranty. I could probably get up to speed and figure it out, but I don't have the time lately to learn something new.

I do know that the blower wasn't running this last trip with the system commanded to heat. It also didn't work when I commanded the fan to on without the heat running. I do know that the signal was getting up there, I at least checked that when I was waiting on the HVAC guys, so it isn't a thermostat or wiring problem, all the signals are going where they're supposed to.

on a household AC unit the compressor is in the condenser unit so the pressure switches should be out there for that stuff. I can't see even if it shut down on due to overpressure that once it sat turned off the hi press cutout should eventually reset... because it is not like any AC system that isn't running doesn't equalize pressure after a shutdown.

with the blower motor is inside the house in the air handler.. you'd think if fan motor wont move air it was something related to the fan or fan control circuit it self.. just because most of them run the fan for reasons other than AC or heat. Did you try tapping on the fan motor with a hammer or giving it a spin?

 

[ctechbob]

on a household AC unit the compressor is in the condenser unit so the pressure switches should be out there for that stuff. I can't see even if it shut down on due to overpressure that once it sat turned off the hi press cutout should eventually reset... because it is not like any AC system that isn't running doesn't equalize pressure after a shutdown.

with the blower motor is inside the house in the air handler.. you'd think if fan motor wont move air it was something related to the fan or fan control circuit it self.. just because most of them run the fan for reasons other than AC or heat. Did you try tapping on the fan motor with a hammer or giving it a spin?

This system will lock out the compressor after 5 high-pressure trips. So if the pressure switch is tripping prematurely, that's why the compressor keeps getting locked out (Or it can be a faulty control board). Once it is locked out, the only way to reset it is to power cycle the unit. It is programmed to never unlock once locked otherwise. That makes sense, you don't want it powering back up a possible problem.

Fan motor spins perfectly and gets all the correct voltages, so it is likely something in the fan controller. Thankfully, if it is, I don't have to pay for it, they're something like $300 just for the controller.

This is what the controller looks like. Control circuitry potted on the back of the motor. Better and worse, all at the same time!!

 

[MSCH]

This system will lock out the compressor after 5 high-pressure trips. So if the pressure switch is tripping prematurely, that's why the compressor keeps getting locked out (Or it can be a faulty control board). Once it is locked out, the only way to reset it is to power cycle the unit. It is programmed to never unlock once locked otherwise. That makes sense, you don't want it powering back up a possible problem.

Fan motor spins perfectly and gets all the correct voltages, so it is likely something in the fan controller. Thankfully, if it is, I don't have to pay for it, they're something like $300 just for the controller.

This is what the controller looks like. Control circuitry potted on the back of the motor. Better and worse, all at the same time!!

View attachment 1760

you said you have to reset the unit by cycling the power.. effectively a reboot.

I have a Trane unit on my house, it is what I call Hi Tech.. 2 compressors, 20 SEER. I known enough about it, ( we get quite a few power outages where I live) to understand that sometimes the unit doesn't function like it should and it probably got power surged and got a case of Bipolar... , so I go out to the main panel and turn the power off to the unit for a minute.. and reboot it and it will work fine..

 

[ctechbob]

Fan motor replaced this afternoon. Currently everything working as designed. Now I get to keep an eye on it to make sure the compressor doesn't kick out again. Fingers crossed that everything keeps on trucking.