Carrier RTU VFD needs Y2 for full speed
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- Опубліковано 5 лют 2025
- Just a heads up that the SINGLE STAGE Carrier RTU's with the factory Blower VFD will not speed up to 100% rated CFM unless you connect Y2
When not using an economizer, such as on this particular one, then it is as simple as adding a jumper to Y1 and Y2 so that Y2 is also energized for cooling and the fan speed ramps up to max.
A fan only call will operate the fan at 40Hz
If an economizer is added then a 2 stage thermostat MUST be used (as it always should be regardless on single or dual stage unit) and you're pretty much stuck with 40Hz on single stage in that case until Y2 is energized.
UPDATE:
*There is a yellow and a white wire hanging loose on the wiring harness next to the VFD*
Just plug those two wires into each other and the VFD will run on 60HZ (full speed) any time you operate the fan.
This is something they made handy for doing test and balance to get the fan to 100% with fan only.
Else jumper Y1 and Y2 so you get 40Hz on fan only (G) and then Y1/Y2 will switch it to full speed during cooling.
Those jumpers!!! please make a video on how to build one, I'll pay you 💰 🤑
40hz and 60hz. Y1 and G is 40hz....everything else is 60hz. The 24vac call goes to a rectifier board with relays that send dc to the drive for 1 of 2 speed reference signals. AI1 I believe is 40hz and AI2 is 60hz.
Damn I will have to check some of our units we installed for this issue
It's really overlooked on the new EcoBlue axial fan models. Especially the 6 ton 48/50FCQ07 and the 48/50GCQ line that techs don't realize has a 2 stage scroll in there.
No Y2 means only 70% capacity.
Awesome video
Thanks for the info .......
Haven’t seen any of those out here in the dfw area but look forward to it another thing is where did you get that awesome gadget from ??? Would love to own one ??
The "jump-box" is home made.
If you made them I would definitely buy one .....👍👍👍
So should you have tstat wire run from tstat to RTU and terminated on Y2? I found same deal on Carrier RTU with VFD. Just replaced VFD and customer said they been having problems since it was installed couple years ago. Looks like it only has Y1 speed
On Carrier units if it has a VFD it is a 2 stage unit. Those are the only ones that had the VFD factory option for medium rooftop units.
This was an ICP and seemed to have them added on these single compressor units. I have not seen an ICP like this since this time.
For Carrier:
40Hz when G is energizes.Y1 brings on 1st stage compressor. Y2 brings on 2nd stage compressor and blower motor now at 60Hz for full speed.
@ ok thanks. This Carrier RTU is a single compressor unit. Looks like the VFD is only to bring the blower two speeds 40 and 60 hz but doesn’t have Y2 hooked up. Probably needs Y2 for 60hz.
I’m wondering the low voltage tester if make them to sale?
I do get asked sometimes. But the only way I could sell them would be for someone to make them in mass to make it cost achievable.
Buying a plastic project box alone can cost 10 to 20 $
Then the alligator leads, circuit breaker, etc.
what kind of jumper tool do u have? i want one
Home made
So without the y2 connect it won’t run?
It needs Y2 to run at 60Hz (full speed) to get the rated CFM for the capacity of the unit.
If you only power G and/or Y1 then you get 40Hz and your blower is operating at approx 2/3 of it's rated CFM.
Which is what you want IF it is a 2 stage unit but not if it is a single compressor/single stage unit.
Some of the smaller models (04 to 07 I believe) can have the single compressor with 2 stages and then you will want to run the blower at 40Hz for Y1 and then 60Hz for Y2.
That big pile of wires going through the blower cabinet and to the drive is such a joke. Is it that hard to use proper multi-conductor cable and terminal blocks to tidy things up?
I think that was all factory wiring too
Absolutely shameful, especially considering the cost of these RTUs. Guess the extra $40 per unit to have terminal blocks and cabled wires is just too much for Carrier.
@@AmericanLocomotive1 Bro. I got it straight from a disgruntled former Carrier Service Manager. Carrier always uses 2 pole contactors on 3 phase equipment to save money. If Carrier can cut a corner to save one penny per unit, they will do it. Carrier is a shit company.
I see some minor improvements in these new units. But they need to up their VFD game a bit. Trane has great user interface for monitoring and configuring their VFDs, and units in general, easily accessible electric part, etc. Lack of proper cable management is a joke. These cables are going to rub out and short, not to mention, it makes cleaning the blower harder.
Also, if you are specifically looking at checking current to VFD / motor, you should close the side panels, as that will add extra load to maintain same speed.
I have to correct you haha. On Tranes smaller RTU's you have to remove the blower access panel, insert half your body into the unit, turn awkwardly to the right, and try to read the screen while without touching the belt and pulleys while it gives you bullshit numbers because the blower access panel is off haha. They SUUUUUUUUCK to use!
@@jman0870 That is true. I saw such arrangement on Trane Voyager. They look to be simple retrofit of existing design indeed. The bigger models, do have VFD in electrical panel instead.
@@movax20h Yeah the Intellipaks and larger Voyagers have a remote drive display in the electrical panel. The small Voyagers do not and they are a bitch!
What is the name of that thermostat tool?
It is home made. Just a box with rocker switches so I can connect the wires then just flip the switches
Where can I get those jumpers?
It's a recycled box, jumper wires from Amazon, rocker switches from Digi-Key, and a circuit breaker from an old transformer.
@@hackfreehvac you should make a video of how to build one
They dont last
Whole VFD to achieve just two speeds, worth it!? 😂
It is only on some sizes, so it must have been done to achieve an energy rating.
Removing inrush meets new SEER/EER/whatever rating your area has. It's why all residential equipment is pretty much ECM and compressors are slowing moving to inverter.