Condenser temp sensor/ controls fan help needed

[matthewthirlwel]

I am working on an Ice maker. The pressure/temp. switch that senses the condenesers temp and brings the fan ON/OFF has failed twice. I linked it out and wired the condenser to run all the time. Now during defrost it struggles to melt all the cubes sufficiently to drop. Is there a way I can control the condensing fan to switch off during defrost. Could I take the power to the hot gas solenoid To control an "Off" switch to the fan. I dont want to Braze another temp. switch as that will be the third and if it fails the customer will be screwing .Please Help

[monkey spanners]

Why is the pressure switch failing? Is it a poor quality part or is it being over loaded either by pressure (dirty condenser, intermitant fan motor or power supply problem) or is it failing electricaly possible agian due to faulty motor or wiring short pulling too much current etc.

I have in the past fitted a proper adjustable high pressure switch to an ice maker when the correct part would have taken too long to get, depends on the space in your unit.

[matthewthirlwel]

The factory one failed an engineer replaced it with like for like its an italian machine and apparently parts have to be ordered from Italy, I assume its just a low quality part. does it work by pressure or temp.? its a tiny thing about the size of a penny with two terminals on top. Do you know of a switch that makes when no power applied and breaks when power is applied I was thinking to wire it in series with the hot gas solenoid that is only powered during defrost. if a "proper" pressure switch is brazed in how would i know what pressure ranges to set it too.

[Brian_UK]

Can you not wire in a small power relay to the switch so that the fan is powered through the relay?

[charlie patt]

the reason its not defrosting well is due to the fan on the presure migrates back to the condensor more than it should and as you no lack of pressure as ms says you could fit a ranco pressure switch or you could fit a non avaisive sensor or another option if it has a timeclock use the neutral of it to control the condensor neutral but just check the presures during df

[matthewthirlwel]

This sounds appropriate Could you please specify a relay that would work. Much appreciated.

[Brian_UK]

An relay that can handle the power load of the fan, an 8pin jobbie from RS would probably cover it without problem.

[matthewthirlwel]

Is it straight forward to wire it up so when the hot gas solenoid (defrost) is energised the power OFFS to the fan.

[Brian_UK]

Yes, the fan would be wired through the normally closed (NC) contact of the relay.

The relay coil would be connected to the defrost signal and when the relay is powered the NC contact will open and break the power circuit to the fan.

[mbc]

all these information is right when you have one small cooling system(one compressor with (1-2 or3 Evaporator)
in large system it should wired independently though pressure switch . Why?
in large system might one or more rooms will be in running position and one or more rooms in defrost position and so your one or 2 compressors will be in running position , in this case you should control your condenser pressure by high pressure to get good defrost result and also your system should works in different out side temperature.
So best thing to control it is a pressure switch

[Brian_UK]

Maybe so MBC but as was stated in the OP first post, he has an ice-maker.