HVAC guys?

[Cody]

Anyone in here an hvac person?

My ac wouldn't turn on this year. Last time this happened I paid like $380 to have someone do a dual run capacitor. I went and bought the cap from mountain land and replaced it, but still no go.

So I paid my normal hvac guys $150 to come out. The lennox furnace isn't sending 24v out to triger the hvac to kick on and said it would need a new motherboard..(they said) For $1300. I bought a motherboard for $130 and swapped that out and still the same thing.

I have 220 at the breaker switch next to the ac, and the furnace and fan all work, it's just not turning on the ac. I'm honestly not sure exactly where to be testing on the furnace side for 24v, but I don't have voltage on what appears to be the control wire outside on the ac.

So... Any ideas? Anyone willing to work for beer or 3d printed cookie cutters?

 

[J-mobzz]

Is the 24 V transformer at the furnace working? I had this exact thing happened to me at an old house of mine and that’s all it was.

PROTACTOR Universal Furnace Transformer 115-208-240 Volt Primary 24 Volt Secondary 40 VA https://a.co/d/iFiUW5N

 

[Cody]

Where the hell is that at..

If it was the transformer, wouldn't the thermostat not work either?

 

[The_Lobbster]

I do HVAC. If you’re not in a hurry, I’d be happy to come take a look Thursday, I’m off all day, and would happily work for beer.

 

[The_Lobbster]

Where the hell is that at..

If it was the transformer, wouldn't the thermostat not work either?

Yes, unless the thermostat is battery powered. Transformer is in the furnace by the circuit board. There is a little 3 amp fuse on the board you can check, if it’s blown, that means you have a short somewhere in the low volt line.

 

[OldGeezer]

I could use some help with mine too. Outside fan comes on for a second then turns off for a second, comes back on for a second then off. Over and over. I'm off Fridays, Saturdays and Sundays.

 

[The_Lobbster]

I could use some help with mine too. Outside fan comes on for a second then turns off for a second, comes back on for a second then off. Over and over. I'm off Fridays, Saturdays and Sundays.

Probably cycling on a pressure switch, potentially low on refrigerant. Pm me with deets, I could probably take a look.

 

[OldGeezer]

Thanks

 

[Cody]

Yes, unless the thermostat is battery powered. Transformer is in the furnace by the circuit board. There is a little 3 amp fuse on the board you can check, if it’s blown, that means you have a short somewhere in the low volt line.

Seriously, thanks for coming by. You really know your way around an hvac!

 

[The_Lobbster]

Seriously, thanks for coming by. You really know your way around an hvac!

Thanks for the beer! The Feelin’ Loopy is purdy dang good!

 

[nnnnnate]

I got home from trek yesterday and my upstairs AC unit isn't cooling. Apparently this started Wednesday. Blows air but it isn't cooled much at all. I took temps at the ceiling register and it was like 76 and ambient air was 82. New construction so these were installed July 2018.

The thermostat is an ecobee and its calling for cooling but the cooling isn't happening. I changed the air filter about 10 days ago, still checked it anyway and its clean.

I'm thinking maybe its a capacitor? Anyway, I've got two units (one for 3rd floor and one for main/basement) so I'm thinking if I can figure out where the capacitor is on the unit I can swap them to try and test that that is the problem.

Is my logic sound here or am I missing something else that would be causing this issue.

 

[SLC97SR5]

Your troubleshooting is sound assuming the capacitors are the same value.
You can also verify the fuses/breaker is good for the condenser as well as the contactor.

 

[nnnnnate]

The two outside units have the same model number so I would think the capacitors should be the same.

The fuses for the condenser/contactor are going to be in the panel on the ac unit right?

I wish I would have thought of this stuff last night and not at 3 am and on my drive into work this morning...

 

[Pike2350]

The capacitor would be on the AC unit. The fuses are likely in the disconnect panel by the AC units. Is the condenser spinning when the system is calling for air or does the outside fan not spin? If it doesn't spin then your trouble shooting is sound. Fuse is more likely given the newness of the AC units

 

[The_Lobbster]

Make sure the outdoor unit is running for the upstairs unit. If it’s not, check the breaker, and disconnect at the unit to verify it’s on.

I’d recommend checking your warranty to see if you have any left. The company I used to work for offered 5 years on new construction. Worth a check at least.

If you go to the outdoor unit and it’s not running, pop the electrical door off (make sure to kill power at disconnect first) and check the capacitor. If it’s bulged, it’s bad, but they don’t always necessarily bulge when they do fail. If you can post a pic with the MFD, I can pick one up for you, to at least take that out of the equation. They are generally about $12.

 

[SLC97SR5]

Check the air handler board for codes.
Being it is the upstairs unit, is the air handler in the attic? If so, you can check the condensate float switch to make sure it is not tripped.

 

[Jesser04]

We just had the capacitor go out on ours the fan was running but the compressor wasn’t. Took the guy 5 minutes to change it.

 

[The_Lobbster]

Check the air handler board for codes.
Being it is the upstairs unit, is the air handler in the attic? If so, you can check the condensate float switch to make sure it is not tripped.

Rarely will the indoor unit flash codes for the AC unless it’s a communicating system, which builder grade typically doesn’t include unless you specifically order it that way.

 

[nnnnnate]

The fan does spin outside. I checked to see if anything was frozen like we had happen at our other house and the pipes leaving the unit were not.

I did play with the condensate float as that stuff is in a little closet upstairs and accessible. It seems fine. When I mess with the float it kills power to the thermostat which has been powered on. In fact I got a notification from ecobee telling me that there might be an issue because it has been trying to cool for hours and the temp never decreased.

I'm running home now to check the capacitor so I can get a part after work if needed.

 

[nnnnnate]

The unit was installed 7/16/2018 and we moved in 12/2018. The paperwork I saw mentioned a 5 year warranty but I figured they would go off install not move in. If it's something expensive I thought I'd try that route anyway but I'd rather try and diy my way out of it first and not have to pay the eyeball fee.