R404A to R448A - motor overheat problems

[kfjoe]

Has anyone else experienced motor overheat on compressor after switching to R448A ?

[Glide]

Did you change the TXV also?

[kfjoe]

Hi

Its and EEV and have adjust settings for superheat

[Glide]

Does the controller have R448 in it's memory?

[Brian_UK]

What is the compressor suction temperature and is it within the compressor design specifications?

[kfjoe]

within specs of below 20k suction superheat at comp
comp design spec shows on the limit for additional cooling

[kiwifridgie]

Eev sensor/sensors should be changed at time of retrofit. If driver has no r448 setting - use r22.
A good eev driver will use 1temp sensor 1pressure sensor, a cheap one will use two temp sensors. Either way,, change em.
Superheat at comp is specified by manufacturer.

[Glide]

Eev sensor/sensors should be changed at time of retrofit. If driver has no r448 setting - use r22.
A good eev driver will use 1temp sensor 1pressure sensor, a cheap one will use two temp sensors. Either way,, change em.
Superheat at comp is specified by manufacturer.

Hi kiwifridgie, can you please explain why the sensors need to be changed at retrofit?

[kiwifridgie]

Sensors are cheap and easy to change. Not suggesting change pressure transducers, just suction line sensors.
Moisture issues can cause erratic readings that correct themselves when the sensor warms up again.
I have changed slot of evap sensors for this very reason. Air sensors, not so much. But a retrofit to new gas costs slot, and sensors are a cheap and easy thing to do.
A simple thing is sometimes the hardest fault to spot.

[Glide]

You are referring to a temperature sensor which measures superheat?

[kiwifridgie]

Every eev driver I have encountered is controlled by a driver that uses either two temp sensors or a pressure transducer plus a temp sensor. It controls superheat.
All I am saying is that a system faulting on motor overheat can be the result of erratic eev control due to faulty sensor.
There are multiple reasons for motors overheating, most of which are obvious when standing on site. I am assuming that the fault is occurring when no-one is around to see it. Hence my suggestion of an erratic sensor. The sensor will be strapped to a suction pipe.
Kfjoe has stated that he has checked superheat, one assumes he is also capable of checking voltage/ current , contactors, fans and other system controls that can cause problems.
Just suggesting options to consider.