how inverters control condensation pressure ?

[Yuri B.]

Hello
How an inverter split air conditioner is controlling the CP with its discharge, pipe, and ambient temperature sensors ?

[The Viking]

That will to a certain degree depend on what manufacturer you are looking at. Generally for modern equipment from the main manufacturers:

- The discharge thermistor is used to protect the compressor from overheating by shutting the system down somewhere around 115-130ºC
- The liquid line thermistor will vary the outdoor fan speed (And thus the head pressure whilst in cooling), unless there is a pressure transducer performing that task.
- The ambient thermistor will prevent the unit from running outside it's design envelope but might also be used for other algorithms, like defrost control.

:cool:

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[Yuri B.]

I was thinking almost so precisely too, thank you anyway.
What actually caused me to ask is the diagnostic message (leds blinking ) on an Fujitsu inverter: "Cooling high pressure abnormal rise".
Anything seems ok, only the condenser looked not to be very clean. But the fan was not speeding very high by that, what I would expect from the a/c algorythm in such case.

[Brian_UK]

You can get the fault sometimes because the coil is dirty but the 'air' sensor thinks that all is well.

It can be fooled sometimes by putting the air sensor into the condenser coil fins so that it responds to the increased coil temperature. Not highly recommended though.

[The Viking]

Aha,
Fujitsu....

They were keeping to ambient temperature switching the outdoor fan from high to low until fairly recently.


:cool:

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[Yuri B.]

Fijitsu "inverters" have BLDC motor fans.
Unfortunately, almost solely the Daikin put out explicit descriptions of its products - most of other manufacturers go often very reserved on information concerning what they produce.