York, YTJ3K3E2

[Alpha-Tech]

I have a R-123 machine with the evap. pressure transducer reading about 3 to 3.5 psia lower than actual. This is causing the chiller to trip on low evap. pressure after only running for a minute or 2. I don't believe the transducer is bad as I can switch the sensor harness with the other transducers on the low side of the chiller,( low oil & turbomodulator transducers), and still get the same reading. Is it possible that the main processor board is at fault. Condenser press. transducer reads 11.5 psia when machine is off & pressures equalised which is what my gauge indicates but evap. tranducer reading 8 psia. Are there any other checks I can perform or has anyone come across a similar problem. Any input would be much appreciated.

[york56]

What is the head pressure when it runs and does it surge because if it does it will give you that fault because the lchwt and the saturation temperature are most likely greater than 2 deg. apart after 2 min. of run time your done machine will trip out.

[klove]

Is it possible that the main processor board is at fault.......

Yes. But not necessarily.

Post a complete model number. Does it have an Optiview or one-line panel? If a one-line, what's the panel number? These will allow us to look up the correct part numbers and get accurate info for you.

Mostly, you've been here since November 2008. Surely you've read these other threads where people have been told to put something in their profile. If you want technical info on large tonnage equipment, put something in your profile so everyone has an idea of the experience and background of the person they're speaking with.

[Randy S.]

Got air in it?

[Alpha-Tech]

Model# YTJ3K3E2-CRG, Serial# GEDM261007. CodePak panel(single line).
Panel No. 371-01200-002, Wiring Diagram 035-08931-000. 525 tons
Head pressure gets to about 12psia & evap. pressure trips at 4.4psia after short run time( under 2 min.)No surging. Standing pressure in both barrels after they equalise measures 7 in/hg. Condenser transducer reads 11.5 psia. Evap. & low oil transducer read 8.25 psia. Evap. transducer P/N. 025-29148-002. Followed checks in the service manual for transducer output voltage vs. input pressure which checks out ok. except for the wrong pressure. I thought the Micro board might be the problem but was able to swap it out with another chiller & got the same results.
My profile is now filled out. Sorry if I offended. Even though I joined the site in '08 I haven't used it until recently so everythings still new to me.
Thanks for any input.

[klove]

No offense intended or taken, just a common oversight.

Normally, the problem you're describing would be attributed to a micro board converting the signal incorrectly, but you say the other board did the same thing, and you have 2 different transducers reading the same (are they the same part number and have they by chance been replaced?). Try unplugging all of the transducers and temp sensors, and reconnecting them individually and see if that straightens things out. Also, check your regulated voltage supply to the sensors and see if it falls in range. Was this chiller converted from 11 to 123?

[aceairman]

" I can switch the sensor harness with the other transducers '

Are you getting your readings at the input terminals directly on the microboard? (AI signal input and board ground terminal). It sounds like your troubleshooting has left the harness factor in play. Don't trust the harness!

[chillerfreak]

Single line panel mother board has a solid jumper that say's R-11 on it that has to be clipped if you have a 123 machine...I've had this problem before and if not clipped it will cause the machine to trip on low pressure....if that is not the problem try unplugging all sensors, transducers and level sensor if you have one.....plug them in one at a time while checking your voltage....I have typically found a bad transducer to be dragging down the voltage on some random sensor...go figure....good luck!

[CumulusMech]

I have a R-123 machine with the evap. pressure transducer reading about 3 to 3.5 psia lower than actual. This is causing the chiller to trip on low evap. pressure after only running for a minute or 2. I don't believe the transducer is bad as I can switch the sensor harness with the other transducers on the low side of the chiller,( low oil & turbomodulator transducers), and still get the same reading. Is it possible that the main processor board is at fault. Condenser press. transducer reads 11.5 psia when machine is off & pressures equalised which is what my gauge indicates but evap. tranducer reading 8 psia. Are there any other checks I can perform or has anyone come across a similar problem. Any input would be much appreciated.

There must be a way to calibrate the evap sensor . I have seen this before with similar deviations on Carrier machines .

[Alpha-Tech]

Just wanted to update my problem with the transducer reading low on the York low pressure machine. Turns out it was just a bad transducer after all. Once replaced, pressure reading was correct. Sometimes I overthink things. I guess I just need to Keep It Simple Stupid! What a humbling business. Thanks for everyones input & advice on the subject. This forum is a great resource.