Refrigerated units on Drycleaning Machines

[jamcool]

Guys,
Does anyone have any manuals on refrigerated units that are used on dry-dry drycleaning machines?
A problem has jumped up on a Multimatic drycleaning machine.
When unit is on its longest drying cycle the comp. gets so hot that the internal thermistors open. all other short cycles are ok.have only done small checks to unit will be spending some time on it 2morrow but this is what i have so far: suction 1.5 bar
discharge 16 bar
water cooled condenser and 2 coils in the dryer,here is the cycle:D In heat ,gas leaves discharge into heat coil(coil in drum) then out to water cooled condenser through drier,sight glass and expansion valve into evap. (that is also in the dryer drum) then back to comp.
In the cool stage, the hot discharge gas does not enter the heat coil but goes straight to the water cooled condenser and unto a regular fridge cycle.(2 solenoid valves control the cycles)
On both stages there is a fan that moves air in the drum.
There is also a steam coil that uses steam in the heat stage along with both coils on the refrigerated system.
Will be pulling the drum to see the condition of the coils and how they are situated,also will be taking some temp.readings,the system is on R22.Also sight glass flashing
Long one :D I know. so any manuals please send my way:D The cycles i just describe is based on my observations while running the dryer.I could be wrong:o

[Brian_UK]

Sight glass flashing would indicate a gas shortage, but needs checking - gas shortage equals hot compressor.

[jamcool]

Thanks Brian,Yes,its short on gas,planning to search for the leak,as there is no charge weight will do to a clear sight glass while watching pressures.My request for info still stands:) as there is no paper work on this machine,the cycles I spoke about are correct after running unit through its programs.But would still love to leave a manual for the next guy who might come to this unit."The more one helps the more one is helped" my own quote:) Thanks again

[ableis]

Hi Mate,
Not sure if you've got the info yet but here's a quick run down. The Fridge process on a dry cleaning machine works in way that almost mystifies the avergage fridge engineer. The compressor will run flat out for the length of the dry cycle. High pressure should be 20bar for sealed compressors and about 15 bar for the old style prescold piston type. (higher pressure causes head gasket failure) Low pressure is dependant on set point of the expansion valve and circuit design but in practice it's usually between 3-5 bar.

The dry cycle is split into 2 segmants. The heat cycle and cool down cycle.

During heat the high pressure circuit will be fed through a coil and the temp of the gas (at 20bar on R22 or R404 between 48-55'C) will aid heating of the garments. during cool down, solenoid valves will swap over and the high pressure goes straight back to the receiver. Receivers are almost ALWAYS water cooled.

Now for the Tricky bit... Faults on dry cleaning machine fridge units can be any number of things and not always a fault with fridge it self. For instance, poor air flow within the machine can cause too low pressure on the LP circuit. and misslead the actual fault.

As for your machine... overheating compressor and low HP is lack of gas. Turn off the water-feed to the machine, if the HP gauge fails to rise then not enough gas. This is of course visible in the sight glass but not all machines have a sight glass. The receiver will almost always have a capacity label on them for re-filling.

When the dry cycle is finished the compressor will switch off and over a period the system will equalise. Remember... Too low LP can bring liquid back to the compressor!!!! But also don't get confused with blocked suction which also causes low LP and a blocked filter/dryer is quite common on old circuits or where a repair was carried out previously.

Hope this helps.
David.