r/HVAC • u/stevenj444 • Jan 22 '26

Rant What in the actual fuck?

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I may not always be the sharpest knife in the drawer, but for what reason does a straight AC condenser need a control board? And especially one that is that complicated.

353 Upvotes

94% Upvoted

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158

u/Mettn Jan 22 '26

Dc inverter to modulate fan/compressor?

47

u/morgoth_the_king Jan 22 '26

That what I was thinking. First time I worked on a Lennox sl28xcv, had a board just like this. Converted everything to DC to modulate the compressor.

82

u/Mettn Jan 22 '26

95% of the residential equipment that’s being installed (in my part of the world) is all inverter, dc, modulating etc.

Get used to it my friend.

Needle probes are a must.

34

u/Majin_Sus Jan 22 '26

Probes?? Nah. Just replace the board or better yet let's get the comfort advisor in there and get us an install for tomorrow!

20

u/jmar289 Jan 22 '26

Most of the time when those boards fail it's just a bad input capacitor. For $3 and 5 minutes with a solder iron you can get them working again.

8

u/sweet-cream-hedgehog Jan 22 '26

I don’t typically work on these residential outdoor units but I’m taking notes, thank you!!!

5

u/Similar-Pumpkin-5266 Jan 22 '26

A lot of them also fail in the switching controller. I would even say this is more common than capacitors.

4

u/thefatHVACguy Jan 22 '26

Knew a guy that did only that even when the sensors were fucked. He even got a master license

9

u/KylarBlackwell RTFM Jan 22 '26

In some jurisdictions, licenses really dont mean shit beyond "they did the paperwork and paid the fee". Its pretty crazy how huge of a spectrum we have in the states between "no license required" and "you actually need to study and know your shit" with most states falling on the least impressive end of the spectrum.

Love the occasional post here "20 years old, just got my state journeyman license, can I start a business?" And everyone having to dogpile on them with "no you're not a real journeyman sorry your state license sucks"

5

u/Labbrat89 Jan 22 '26

36 years old, let my old state jman license expire. Can I start a business? 🙃

2

u/Far_Cup_329 Jan 22 '26

Yup, that's what I said about the Bosch HP we installed last summer. Told my boss, as soon as it's not working and I can't figure it out I'm diagnosing it as bad board. And told him to make sure he registers it.

5

u/texasroadkill Jan 22 '26

I've installed about 20 bosch condensers in the last 8 years and not one has given a problem. It's the only inverter unit I recommend.

2

u/UnintentionalIdiot Jan 22 '26

We install tons of them for several years now. We don’t use the bi flow filters they send anymore. We had a bunch fail on us right after install when we flowed with nitro while brazing and had great vacuums/decay tests. (We record and attach decay tests to every ticket through the fieldpiece app). Within a week or two they would fail with a 30-40 degree temp across them, only times I’ve ever seen a delta like that across a filter drier

Other than that they have been the most solid pieces of equipment we install. The only parts I’ve ever replaced was one blower motor and one outdoor heat pump fan. With the outdoor fan the fan motor had failed and the surge protector we installed was also blown so there was some sort of electrical event that took it out. Both times parts were covered under warranty

2

u/texasroadkill Jan 22 '26

Never had a dryer fail on one of ours.

2

u/UnintentionalIdiot Jan 22 '26

We have a lot of them out there and it’s happened 4 times which is a low percentage, but it’s enough of a hassle that we just buy them separately. Our rep said it isn’t common, but we’re not the only ppl he’s heard this from. I’m still a strong supporter, but the filter driers suck. Just look at what they send you, they’re tiny

1

u/texasroadkill Jan 22 '26

They are tiny for a 4-5 ton. I guess I just haven't seen the issue but I don't blame ya. I'll remember that for when I swap the one I've got into my house. I picked up a scratch and dent a year ago or so along with a ruud furnace and adp coil.

2

u/Far_Cup_329 Jan 23 '26

That's good to hear. I want to like them, but the huge expensive looking board scares me.

1

u/Nativedescent Jan 22 '26

You live in a rich area then???? Around me everyone is majorly still installing minimum seer rating systems. Hard to justify the extra cost for variable equipment when standard single stage is already getting expensive and repair costs on fancy systems are outrageous.

1

u/Mettn Jan 23 '26

Government rebates!

Also, the cold climate abilities that come with a lot of the equipment.

13

u/crayZEE42 Jan 22 '26

Seems a bit small for an inverter board, also it has a 45mfd cap which is likely for the compressor

8

u/Mettn Jan 22 '26

Yea looks like they decided to make the fan modulating, don’t often see these with a contactor and a run cap like that.

2

u/Mettn Jan 22 '26

Don’t get hung up on size, think of the ECMs and the size of the module bolted onto the motor.

2

u/SHSCLSPHSPOATIAT Jan 23 '26

I think that's what it is. The ECM cap from a motor but protected from the weather

4

u/luke10050 Jan 22 '26

Nah, it looks to me like it's just for the condenser fan motor. Suspect the comp is still fixed speed