[lash61101]

Was doing pm on unit and found huge temp drop from discharge into cdsr and out. It enters cdsr around 146 degrees and leaves around 65 degrees. We evacuated system, vacuumed down and recharged system. We have subcooling of 22 degrees. (407c) refrigerant. My question is the outdoor temp is around 32 degrees and the cdsr fan is controlled by a pressure transducer, only thing I can think now is that the transducer isn't working properly and fan is sdischarging too much heat. I looked online for specs of transducer and cant find, my boss doesn't want to spend the money on a new one. Any advice would be welcomed.

 

[pecmsg]

Where is the sensor mounted and what happens if you remove it?

 

[gravity]

Its a pressure transducer mounted on liquid line. Measure VDC going into the VFD. Also measure the output of the power supply. Should be 5.0-5.1vdc. No more and no less. The transducer is most likely bad. Ive replaced a few. What is this your liquid line pressure? The drive should maintain around 100-110 condensing temp.


Sent from my iPhone using Tapatalk

 

[lash61101]

if I remove it, the fan goes to full speed.. The liquid line pressure is 176

 

[atmosphere]

Check your condenser fans Tstat settings and calibration.

 

[ruuufuhbock]

Are there any performance issues here or you just noticed a big temp drop?

 

[aastyler]

If there are other ambient t-stats make sure they are set correctly and those fans they control are not running. Some of the transducers are set to 190 psi and others are at 210 psi. By 165 the fan should be fully off. One thing I noticed working on a lot of Lieberts is what the subcooling is when it's low on charge. It's backwards from normal systems. When you are low the subcooling is high and if you add more gas it will go lower. Opposite of comfort cooling Hvac units. If youre ambient fans are set right and not running then try add some more refrigerant and you subcooling will go lower and you'll stack up more in the condenser and raise the head pressure. If you want I can email you the voltage reading chart to check the transducer.


Sent from my iPhone using Tapatalk

 

[gravity]

Is the condenser using a p66 or a VFD?


Sent from my iPhone using Tapatalk

 

[hands]

Does it have a P266 Fan Speed Control. If it does, you may need to set up the parameters for 407c. I have also seen the boards go bad in them and the fan will run full speed all of the time or not at all.