Trane Rooftop DX Units

[bunglebear]

Got three of these packaged units on a site. Two cooling stages in each. The place is hot inside at 82 degrees, but only one compressor is pulling in. I think there is fresh air intake as well, which dampers are 100% open.

Main question I have is that the wall controllers are showing "Cool Fail" I always assumed this meant a safety control had operated. Is this the case??

Suction and head pressures are high (R407C) 86 psi suction, can't rmember head pressure. I think there are non condensables in there, but will find out later on attending. I need to know the cause of the cool fail message. There are no manuals on site. I think the model number is YKH250 ?? so I have been informed.

Any help is appreciated and welcome. Thanks guys.

[Jabarco]

See page #61.
http://www2.jec.com/THKweb/prodcat/ETKH-VII/RT-SVX19A-E4_0805.pdf

Hey, I can't help it if you don't have a laptop notebook in the field with internet access!

[bunglebear]

See page #61.
http://www2.jec.com/THKweb/prodcat/ETKH-VII/RT-SVX19A-E4_0805.pdf

Hey, I can't help it if you don't have a laptop notebook in the field with internet access!

Thanks alot. I managed to get most of the info by looking through old posts.

[makinmoney]

You left out alot of info. "You think" comes up a couple of times in your thread. For any of us to be able to guide you in the right direction we will need alot more particulars...we will help BUT to do so requires more info.

[bunglebear]

You left out alot of info. "You think" comes up a couple of times in your thread. For any of us to be able to guide you in the right direction we will need alot more particulars...we will help BUT to do so requires more info.

That's because I haven't been there yet. All this information is taken from a job sheet from another technician.

[makinmoney]

"ok", Cool fail is a universal fail signal that is generated when any stage doesn't engage. If you look at the way the circuitry is wired you will see the pressure switches are wired in series, so there is no way for the motherboard to know what didn't make. Let us know what you find.

[heatingman]

Got three of these packaged units on a site. Two cooling stages in each. The place is hot inside at 82 degrees, but only one compressor is pulling in. I think there is fresh air intake as well, which dampers are 100% open.

Main question I have is that the wall controllers are showing "Cool Fail" I always assumed this meant a safety control had operated. Is this the case??

Suction and head pressures are high (R407C) 86 psi suction, can't rmember head pressure. I think there are non condensables in there, but will find out later on attending. I need to know the cause of the cool fail message. There are no manuals on site. I think the model number is YKH250 ?? so I have been informed.

Any help is appreciated and welcome. Thanks guys.

The suction pressure is high because the evap temp is high, and only one stage is engaged. Non-condensibles may be a leap.

[The Penguin]

recomend you get your hands on the trane bible - the microtell controls book

I think here on hte site some where they are listed training and edcuation

[bunglebear]

It was a condenser fan motor burned out on each of them. When the second stage tried to pull in, the HP switch was opening. Didn't help that the minimum fresh air setting was turned right up on the board either.
Thanks for inputs