LEV does not open

[Yuri B.]

VRF Mitsubishi, inside unit PEFY-P125YMF-C.
Room air 32C SP 19C - so demand for cooling is great but it wish not to open (at the best maybe some 5% as it slightly frosts only).

I cannot find info on replacement of the "head" of its LEV.

I have tried its PCB on another unit, measured LEV's resistances - all ok. However, now I wanted to try on this unit a LEV from another unit (only the head, not the valve). How I do it correctly, could someone tell me ? (I do not want a refrigerant burst into my face)

[Yuri B.]

That "head" - stepper motor - is about 4cm diameter 4cm long. Beneath it a hex head for a spanner some of 13 to 16mm. Do I take grip of the valve (to prevent pipes distortion) and wrench the hex head with the spanner ? Where - anticlockwise (at left)? Maybe at this R22 ***** model LEV actuator is unremovable ?

[Thermatech]

The LEV valve is made by specialist manufacturer Fujikoki & they supply this exact type of valve to many of the other VRV /VRF manufacturers.

The valve has 2000 possitions ( pulse )from fully closed to fully open when used on Mitsubishi Electric City Multi indoor units.
The needle travel from fully closed with the needle hard set in the seat to fully open is about 2mm.
So every time the circuit board request a change of one pulse the needle changes possition by about 1000 th of 1mm.
This is how VRF manufacturers can very accurately control super heat at indoor coil & make the system very energy efficient.

The valve body is designed to be held with a spanner.
The valve head can be unscrewed using second spanner. The thread is right hand so to remove head turn in anti clockwise rotation. 3 full rotation of 360 deg to completly remove head from valve body.
The needle is located in the valve body & has spring loaded bellows.
If the bellows are damaged refrigerant will leak as you start to undo the valve head the same as it would when you start to undo your gauge manifold hose from service valve. In this case do not fully remove the valve head & proceed to recover refrigerant charge & replace valve body.
This is very unusual so 99/100 will not be a problem.

You have poor refrigerant flow only to this indoor unit & good refrigerant flow to the other indoor units ?
In this case put unit into test cool & after 5 mins start to very slowly remove the LEV valve head 1/2 turn at a time.
This will effectively start to increase the needle valve opening & refrigerant should start to flood through into the coil.
If this happens you will know that the valve head has a problem & is possibly locked in closed possition.
If no refrigerant flooding through the valve then the strainer may be blocked with contamination.

If you want to fully remove the LEV valve head from the valve body always turn power to the indoor unit off. The indoor unit will motor the valve needle into shut possition using the 30v dc control voltage.
If you hold the valve head in your hand you can feel it working & know when it has stopped at shut.
At this point the circuit board & you both know that the possition of the valve is at shut possition.
Then if you put that valve head on another indoor unit provided you made sure that LEV valve was also fully shut before you removed it then you can do the swap.

The indoor unit will have a target super heat of 6 or 9 & in cooling the valve should have max cooling performance with the valve at about 400.
If the valve opens up past 500 & the SH is more than 15 then there is not enough liquid at the valve which can be caused by strainer blockage or system short of gas.
In the service manual you will see description of how to monitor indoor unit data like SH & LEV valve opening by using SW1 & display on the outdoor unit circuit board.
Remember the Mitsubishi SH data will be different from your temperature & pressure readings & SH calculation so you need to monitor it from the system data at the outdoor unit.
The LEV valve opening data is not what the valve is actually but what the indoor circuit board is requesting the valve possition to be.

[Yuri B.]

Thank you very much Thermatech for your TIME and help.

There are two inside units in parallel to the outside PUHY. Another unit works good, but does not cope with the huge demand (there are up to 36C air above the false ceiling which the units take in).

All sensors are good. PCB from the faulty init worked good on the good one. Every unit has its own remote wired control (PAR-20MMA). Demand for cool is present at the controls and at the led display in the outside unit.

The faulty unit's LEV only lets too little refrigerant into its evap even if the good unit is stopped (in case there were little refr in the system) -there only appears some frost after the LEV. When the faulty unit is off, the frost goes away, so some opening/closing is happening, and by that, seemingly no leak.

Tryed the heating mode (in case there were debris in the strainer, so to push them back) - interestingly that by that the liquid pipe covered with thick ice for few minutes (again after the LEV - now on its other side) , then, of course, gone (wondered that there turned to be liquid at such a high temp). Besides, if debris, then that frosting would begin downflow the strainer(s). On the contrary, it starts immediately at the valve.
BTW, the strainer is in that bulge (thickness) about 6cm long on the liquid pipe before the LEV? Where is another ? (I read smwh there should be another - on the gas pipe)

[Thermatech]

Strainers also inside the indoor unit flare nut fitting.
Looks like it might be the LEV valve not opening up if you get frosting from the valve in heating
& cooling.
In heating we would expect hot gas into the coil at for example 70 degC & then warm liquid out & down the liquid line back to the outdoor unit at around 30 degC.
If instead of 30 degC you have frosting then for sure the refrigerant flow is not enough.
LEV valve or blocked strainer.
In cooling mode if liquid floods into the coil when you start to un screw the LEV valve head then you will have found the problem.

[Yuri B.]

I suspected the strainer to be in the flare connection.
Thank you Thermatech very much for sharing your knowledge.

[Yuri B.]

Thank you very much Narkom. Tomorrow I'll try to swap LEVs with a unit from the base floor (there are 2 PEFY's too, working good). I do not cherish the hope that it would solve the prob as most probably the valve (needle, etc) is at fault. Unfortuntaly, my work is only electrical, ***** part do others.

[Yuri B.]

Untill now thought capacity of PEFY-P125 is 125 Btu, it turned out 48 !