A/C Pros in Highlands Ranch area?

[Ramsker]

Well . . . I verified power from the panel to the switch with the fuse. And I have power to the door switch and power from the door switch to the board. I'll try the transformer check a little later--although not sure I know what to do for that exactly. Will try to follow your instructions with the wire identification.

Edit: Anything beyond what I checked to this point is probably well beyond my abilities to fix anyway, unfortunately.

[Ramsker]

Just thinking ahead to the worst case sceanrio . . . if this ends up being a costly repair, it might be worth our while to just punt on the 1990's furnace and upgrade? What are the Tier 1 furnaces and AC units these days (about 3200 sq foot house)?

Hoping it's not going to come down to that, but preparing for my typical luck.

[Ramsker]

OK . . . latest update. I pulled the 2 wires (black and white) from the bottom of the board that run up to the transformer and tested the "tabs" on the board. I have 120v there. I then put those back on and pulled the 2 yellow wires that run from the transformer back to the top area of the board and tested the connectors on the wires. I have zilch on those. That's assuming I did everything correctly--think I did but I am a total noob at using a multimeter. So . . . bad transformer at the minimum???

I did find the lights on the board. There are 2 green lights on the right hand side of the board sort of behind the big clump of wires coming on from the top. They don't light up at all when I turn on the heat and hold down the door switch.

[fitterjohn]

Yes if you have 120v going to the transformer on the black and white you should have 24v on the yellow wires coming from the transformer You can also put the door back on and turn the furnace on. Pull the thermostat from the base plate and measure between the r and g terminal or the r and c terminal if a wire is hooked up to the c terminal and see what you have. I’m waiting for a -40 degree freezer to come down to temp so I’ll be on this for a while to help if need be. And just a good FYI he transformers they sell at Home Depot 90% of the time don’t have enough va to work

[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