Carrier RTU 8.5 Ton Not Turning On Affecting The Weight Room… It’s Getting Hot

Got a work order for AC down in the mini gym weight room, temperature rising and not turning on #hvac #airconditioning #carrier

[@Charlottebaker2764]

A bypassed VFD on a carrier? No way! I swear their VFD quality is terrible past few years

[@subcoolHVAC]

Lol, I guess 1 out of 6 isn’t too bad 😂

[@zekenzy6486]

Great video. Thank you for sharing

[@subcoolHVAC]

Thanks for watching!

[@MarcosHVAC]

I have a site with 32 carriers all 25 tons from 2020. We call it the Covid building. Numerous issues from factory that I caught on start up. Watch out for those insulated terminals for the drive. I had a few burn out on me this spring

[@subcoolHVAC]

Oh man, good to know . Thanks Marcos 👍

[@stevencossaboon3237]

Nice troubleshooting and video Subcool.

[@subcoolHVAC]

Thanks Steven !!

[@ccthepope]

Great video! (as always)

[@subcoolHVAC]

Thanks CC 👍

[@jasonjohnsonHVAC]

Great video

[@subcoolHVAC]

Thanks Jason 😎

[@robmcshane3260]

Don’t you love where the vfd is mounted. F carrier!!

[@subcoolHVAC]

It’s genius 🤣

[@c21meister]

@@robmcshane3260 right in the airstream with all the moisture

[@subcoolHVAC]

You know it 👍

[@maheradous9257]

Good job 👍

[@subcoolHVAC]

Thanks 👍

[@marcelocortez18]

Have have some really good content, u should consider gettin a tripod to show yr work/installations, I think that would be cool to see. Keep up the cool videos

[@subcoolHVAC]

Thanks, the tripod would slow me down, I just try to film as I go and get the repair done as efficiently as possible. I appreciate your input 👍

[@marcelocortez18]

@subcoolHVAC yea I understand

[@jrsmyth9761]

Carrier does have a service/tech bulletin on how to wire around the VFD.
This unit appears to be cool only so low voltage control wiring you did should be okay. However, there is already a signal wire in the unit for this purpose, well it is there if there was no VFD.
Also, I did not see that the wires ran through the fuses that are in the blower compartment. Maybe it is different on 460VAC, I don't think I have worked on anything over 240VAC that I bypassed the VFD on. The fuses are supposed to still be used but need to be changed to a different type.
I usually run the yellow wires that are on the capacitor for the condenser fan motor directly to the contactor instead of to the capacitor. Just my OCD/thing to do.

[@subcoolHVAC]

I didn’t see fuses for the blower , the cfm relay is the weak link to the motors , the yellow motor leads remain energized through the cap common. They already have enough wires shoved into undersized contactors as it is 😂 Thanks for commenting

[@jrsmyth9761]

@@subcoolHVAC
I run the yellows to the same side of the contactor as the common/yellow wire to capacitor is run from.
If there is too much on there, they are not long enough or it is just easier then they stay on the capacitor.
As for the fuses,, there is a block for them just above the VFD, at least on the units I have worked on. Again, maybe different on the higher voltage equipment.

[@c21meister]

Waiting on a vfd now for a carrier

[@subcoolHVAC]

😔we do a lot of waiting

[@Josh.SPublishingTeam2024O]

Hi, i am a new subscriber nice trobleshooting, the wire was crisp

[@subcoolHVAC]

Welcome to the channel 👍 yep, it was a little over cooked !

[@johnpadua9115]

Looks like the sheaves opened up and motor over amped

[@subcoolHVAC]

Set screw was loose but didn’t look like it spun, I was thinking loose wire nut at motor possibly. 🤔

[@caffeinatedinsanity2324]

Not really an hvac tech myself but mostly working on building automation projects yet I also do some service calls from a distance from my office to figure out what is going on. Fishing for information when dealing with problems is always a fun game. Steps I undertake:
-Open the BMS and if there are GUIs created for the sector, open them and do a quick scan on the rooms of the building. Afterwards, narrow down the issue.
Usually, i have dealt with lack of cooling on hot summer days, as opposed to the lack of heating during winter, for some reasons. Most of times they were RTUs feeding cool air to VAV damper boxes.
The first thing I always notice is that all rooms fed by the same system are at least 2-3 °C above their setpoint (usually around 21-22°C), even if the customer tells you only a few are problematic (ex: 27°C, which is really hot).
Either they genuinely had a mechanical problem that needed to be fixed, or sometimes it's just a case of undersized unit. If you see that the unit fails to maintain duct static pressure even when the fan is at 100% speed (because the room controls are all at maximum cooling demand and therefore, maximum airflow) or if all compressors are on and recently maintained but the air is still above 20°C, you can tell right away that the unit is undersized for the building's requirements.
Sometimes I stumble upon autonomous units integrated on the BMS's BACnet network that generally give a lot of info, sometime I stumble across ones where we put our electronics on to control them and the equipments have feedbacks for a bunch of stuff (ex a current transducer on the power lines of the blower, compressor, etc...), and sometimes no feedbacks on the real state of equipments, mostly older installations.
I have limited skills when it comes to troubleshooting machines physically, but whenever I can, I go fish for info for my colleagues who might be dispatched there.

[@subcoolHVAC]

Thanks for commenting, hopefully you found this call interesting

[@Attest411]

Just enough information so you can out source the motor

[@subcoolHVAC]

Yep, motor volts/amps and frame 👍

[@abdullah_q8171]

Motor 3 hp

[@subcoolHVAC]

Yes , that’s what we installed

[@SombraLocs]

Those Carriers are junk!

[@subcoolHVAC]

Willis wouldn’t be proud 🥲