help with atlas copco dryer

[paul441]

Hello guys
I am after some help if possible with a atlas copco dryer,i am fairly new in this game so go easy on me,anyway the dryer, first visit the problem was dryer tripping, so after checking system found comp very hot so thought it might be fault with comp winding, overload, anyway someone else visited job and left solinoid (hotbypass) off.so when i have gone back to job soliniod burnt out now and dryer wont even start now, where before it ran for while and tripped, i have to revisit this job anyone give me advice where to start. cheers

[Brian_UK]

Hot compressors normally mean lack of suction cooling as a first point of call.

Fix the broken parts and do a good visual inspection for leaks.

If there is a data plate with the refrigerant charge details consider pulling the charge and weighing it prior to weighing in the correct amount. People in the past may have added or removed refrigerant.

[monkey spanners]

What tripped when it tripped?
Did it reset by itself or did you have to do something?
Does anything run now, like the condenser fan?

[paul441]

Thanks for reply, the dryer tripped and you could reset but now nothing works when reset ,fan , comp
cheers

[Brian_UK]

Follow the control circuit to find what is holding it off.

Also, is the solenoid valve the correct one for the duty required?

[glenn1340]

Hmmmm, if the solenoid has burnt out it may well have blown a fuse in the control cabinet. I`ve had this before and found that sometimes the problem.
Whats the model? I`ll try to dig out a schematic for it.

Brian`s spot about the running hot problem. Don`t leave it running to long after getting it started as the high temp will kill the pump.

[Magoo]

Pulling off the solenoid coil without electrical isolation would burnt the coil out and trip the control circuit fuse/ CB.
The hot gas injection is required to maintain a dew point in HX to remove water without freezing HX, if hot gas is going hard out and suction at compressor is hot, would indicate system is short of gas, so you have a leak somewhere

[glenn1340]

Just a further idea here and a long shot but I have encountered it before. Is the condensor fan permantly on and the dryer in a cold enviroment if it is the suction side pressure will be drawn down to an extent that the hot gas valve will try to compensate for it by injecting hot gas into the low side close to the compressor. This could account for the hot compressor. Maybe a strategically placed bit of carboard in fornt of the condensor to keep the cold air off would cure it
Oh, and don`t forget to tell the customer that it`s not just a bit of old cardboard box but a OEM supplied bit of card and charge him accordingly