A/C Pros in Highlands Ranch area?

[fitterjohn]

Also check to see if your control board has a fuse. It will be the kind your car has most likely. If you need a new transformer spend the extra to get a circuit breaker or put an inline fuse in with it, you’ll be happy when something shorts again and smokes the transformer. And if you do have a bad transformer that is possibly just the effect not the cause. In my experience something normally shorts out and toasts the transformer. Looking at a wire rubbing through or a contractor etc. in my opinion no matter what it is it’s not worth changing the system aside from maybe a compressor.

[Ramsker]

Also check to see if your control board has a fuse. It will be the kind your car has most likely. If you need a new transformer spend the extra to get a circuit breaker or put an inline fuse in with it, you’ll be happy when something shorts again and smokes the transformer. And if you do have a bad transformer that is possibly just the effect not the cause. In my experience something normally shorts out and toasts the transformer. Looking at a wire rubbing through or a contractor etc. in my opinion no matter what it is it’s not worth changing the system aside from maybe a compressor.

I'll look again, but I didn't see a fuse for the board when I was looking around earlier.

Definitely hoping it's just a component fix or two. The compressor has always run really strong and so has the furnace . . . so we'll see.

[Wulf202]

Sounds like a bad transformer. There's an ACE in aurora that stocks alot of hvac parts. As fitterjohn said, the HD ones are for doorbells and not suited for this application.

Sometimes transformers fry because of a short. check the wires in the brown sheathing to make sure they aren't cut. Also check by the condenser in case someone stepped on them or hit it with a weedeater etc

[fitterjohn]

If you do change the transformer yourself. Set the thermostat to system off fan auto. Turn power on then change the fan to on. Then if it stays running turn the system to cool, if it stays running your good(unless you check heat operation, good techs always do��). If it goes off when you switch too cool then it’s most likely in your 2 wire going to the condensing unit or the contractor, in that case hopefully you put the inline fuse in or else it’s a second transformer. But fear not your compressor should be fine, compressors don’t take out transformers. Or at least I haven’t seen it yet.

[Ramsker]

Thanks again, guys . . . really appreciate the advice and walking me through some checks. I'll try to check the wires again for any apparent issues--didn't see anything that jumped out on initial look. With work the next couple days, I'm probably stuck til the tech comes out on Fri. I'll see if I can get away and maybe pick up a transformer but odds are low I can get away or that I can get one to me before Fri anyway. Not sure I even know how to take that thing out of there but will try to get a closer look.

At least I have a general idea at what might be wrong now. Sounds like it's a good idea to keep a spare transformer around like a spare hot surface ignitor?

[fitterjohn]

Not a bad idea. I keep a transformer igniter, flame sensor, and a cap on hand for mine. But I also do it for a living for it’s just a walk to the van. If you lived near me I drop one off to you on the way home, but your a little out of the way. If you tackle it yourself it’s probably a 5/16 or 1/4 screws holding it in and it’s that simple If they tell you it’s going to be thousands consult on here

[Ramsker]

So, here’s the update. Had a guy come out who has done some work for us in the past (new water heater, some plumbing work) that we’ve been happy with. Ran through what I had found based on the advice here. He smiled and nodded his head and said “nice . . . that helps to know and probably saves some time.”

Transformer was for sure fried, so he said he likes to go with simple and works his way up from there. He grabbed a new transformer with an inline fuse . . . and it killed 2 fuses in a row. So . . . there’s a short “somewhere”. He narrowed it down to a short someplace on the wiring from the thermostat on the main floor down to the furnace. Problem is, we have a finished basement so a lot of that wiring is hidden god-knows-where. That thermostat has been in place for 10+ years, but he said the short wasn’t where he could see it and it could be pretty much anywhere. Said that wiring is not often very carefully put in place and it can rub on metal/pipes/etc and eventually short. The house is 20+ years old so it could have just hit that point on whatever weak spot it had.

He suspects it may have been a wire for a humidifier we don’t use. His concern was whether or not there were enough good wires to still use the old thermostat and have it work. If not, then he said it would be down to either trying to use a thermostat that ran on fewer wires, or if still shorting then run a new wire down (not fun) or just switch to a wireless thermostat—which the only one he had was $$$ and he said he’d rather not go there just yet unless he ran out of options. He ended up getting it wired back up and working with the old thermostat!!! At least for now, LOL. He said he had no way of guaranteeing that there wasn’t another short in the remaining wires that could go anytime—but said that, if it were him, he’d just let it run and call him if there’s another problem and worry about it then.

He told me the control board I had was notoriously bulletproof and that pretty much the only ones he’s ever replaced were from being submerged. So I guess that’s good to hear.
$260 all in to get up and running again. I may look for a good wireless thermostat just to keep on hand in case of emergency down the road to hedge my bets.

[bryjcom]

So, here’s the update. Had a guy come out who has done some work for us in the past (new water heater, some plumbing work) that we’ve been happy with. Ran through what I had found based on the advice here. He smiled and nodded his head and said “nice . . . that helps to know and probably saves some time.”

Transformer was for sure fried, so he said he likes to go with simple and works his way up from there. He grabbed a new transformer with an inline fuse . . . and it killed 2 fuses in a row. So . . . there’s a short “somewhere”. He narrowed it down to a short someplace on the wiring from the thermostat on the main floor down to the furnace. Problem is, we have a finished basement so a lot of that wiring is hidden god-knows-where. That thermostat has been in place for 10+ years, but he said the short wasn’t where he could see it and it could be pretty much anywhere. Said that wiring is not often very carefully put in place and it can rub on metal/pipes/etc and eventually short. The house is 20+ years old so it could have just hit that point on whatever weak spot it had.

He suspects it may have been a wire for a humidifier we don’t use. His concern was whether or not there were enough good wires to still use the old thermostat and have it work. If not, then he said it would be down to either trying to use a thermostat that ran on fewer wires, or if still shorting then run a new wire down (not fun) or just switch to a wireless thermostat—which the only one he had was $$$ and he said he’d rather not go there just yet unless he ran out of options. He ended up getting it wired back up and working with the old thermostat!!! At least for now, LOL. He said he had no way of guaranteeing that there wasn’t another short in the remaining wires that could go anytime—but said that, if it were him, he’d just let it run and call him if there’s another problem and worry about it then.

He told me the control board I had was notoriously bulletproof and that pretty much the only ones he’s ever replaced were from being submerged. So I guess that’s good to hear.
$260 all in to get up and running again. I may look for a good wireless thermostat just to keep on hand in case of emergency down the road to hedge my bets.

I've dealt with many many shorts in low voltage.. I've never been able to NOT find them and/or isolate them and KNOW which wire is shorted either. Does your buddy have a multi-meter? Does he truly know electrical or just enough to get dangerous?

The only reason I ask is because in 14 years I've only had maybe 3-4 shorts in thermostat wiring going up through the walls to the thermostat. Not saying it doesn't happen, and you may have that issue but it's not exactly common.

I have however, had lots and lots of bad contactors cause this exact issue. He needs to either find the short with his meter to ground and/or isolate the AC low voltage circuit from the furnace low voltage.

Let me know what he finds.. Its kinda rare to have a true short in that wiring.

[Ramsker]

I've dealt with many many shorts in low voltage.. I've never been able to NOT find them and/or isolate them and KNOW which wire is shorted either. Does your buddy have a multi-meter? Does he truly know electrical or just enough to get dangerous?

The only reason I ask is because in 14 years I've only had maybe 3-4 shorts in thermostat wiring going up through the walls to the thermostat. Not saying it doesn't happen, and you may have that issue but it's not exactly common.

I have however, had lots and lots of bad contactors cause this exact issue. He needs to either find the short with his meter to ground and/or isolate the AC low voltage circuit from the furnace low voltage.

Let me know what he finds.. Its kinda rare to have a true short in that wiring.

He had a multi-meter. He's the owner of the company and they've been around awhile and seem to have a good rep . . . so I assume he knows what he's doing. It could be that my description of everything is more the problem in my word choice or order and since I'm not great at electrical and don't know that side or HVAC all that well. "Suspects" was maybe a poor word choice on my part. The short that was frying the transformer was in the wire he eliminated from what he was saying and when that was taken out of the equation everything was then working and not blowing the fuse. What he was saying was that he couldn't see or be sure where that short occurred in the line because it wasn't where it was visible . . . and that if there was a spot that somehow rubbed through to short that wire, that it could rub through another of the wires somewhere down the road and short there instead (or it may never happen or it could have been a nicked wire to begin with that finally made contact, etc). I'm assuming he checked other things while he was down there to see if there were any other obvious sources of a short but I wasn't watching him and probably wouldn't really know what I was looking at anyway.

I mean . . . I can only go on what I know (which is not much, but trying to learn) and what he's telling me and advising on what he'd do if it were his house.

When you say "bad contactors"--what would examples of that be? Is that just connectors on the board? I'm pretty remedial with electric and HVAC so I'm trying to get a better understanding of it all.

[Mtneer]

FWIW I'm in the process of installing a heat pump; it's arrived, still looking for a contractor to do the install. Part of that involved upgrading our thermostat to eek out the most performance. Lot's of hype in that market! Nest, Ecobee, blah, blah, blah. Wasted a lot of time sorting all that out.

Ended up going with a Honeywell Prestige IAQ system with Redlink and internet. What might interest you is it only requires 2 wires for the thermostat, all the rest is in a box by the HVAC. Plus all the reviews are pretty much stellar.