ice formation on cooling coil

[ameen pasha]

Respected sir
the problem which im facing from few days is the ice formation on cooling coil with the 45ps suction and 200 psi discharge pressure, i did replace the expansion valve too but not succeded refrigerant is 407c. pls let me know the standerd parameter for 407c air conditioning units.we are using daikin air conditioning unit.

if we not use a equalising line to thermostatic expansion valve is any problem for compressor ?

i hope u wil give a postive reply

[lana]

Hi there,

Your suction pressure is low. Suction for air conditioning wit R407C should be around 60Psi(g).
Your TEV must have external equalizing line otherwise you will have a problem (high superheat and starved evaporator).

Cheers

[ktm]

Are you using daikin indoor and out door? Or is it on a coil in an ahu?

[marc5180]

Your discharge pressure also seems low.

Does the condensor fan have a fan speed controller? Maybe try adjusting to increase the head pressure.

[Gary]

Heat absorbed + heat of compression = heat rejected.

If little heat is being absorbed, then little heat will be rejected. IOW, if the evap is not picking up a normal load (which seems to be the case), then the condenser TD will be low.

We would need a lot more information to determine why the evap is not picking up a normal load.

[wozza]

Pressures are to low for R407C,like KTM said is it both Daikin indoor/outdoor or connected to an AHU.
Are you measuring the true Discharge Pressure or on the service ports of the condenser, which would be suction and expansion line.

[bats100]

I have one coffin freezer consisting 4 12 feet Hill cases Model NZ 120 serial numbers 3756-271,272,273,274.
they are fused together back to back.
one copeland compressor is working in back bone.
in other words its one case back to back.
during defrost cycle, which is stricktly on time based defrosts. 2 freezers are not getting any defrost. but other 2 are defrosting fine. I checked and found that heating element(solid u shape) that is fit on side of fins is not getting hot during defrost.
i read that thermoswitch or thermosensors might be bad, i would like any help on what to look or test first and position of sensors if involved.
i am not professional as rest of team is but can apply your expertise for sure.
thanks for ur time..

[javed]

assalamu- alaikum sir.
you check expansion valves bulb and cooling coil finks, fan motor rotation , evaporator fan speed and machine return air flow .
and last drier filter.
inshallha your problem will solve .

[the chiller]

get the head pressure up!!!adjust fan speed controller.