4 Drawer Cooler Problem

[MikeGardner]

Some guys I'm working with have been having a lot of trouble with a 4 drawer reach in cooler. It is a single unit, but has two evaps and txvs. I believe it had been freezing up on both evaps and had low low side pressure and high high side pressure.

They replaced both txvs but still had the same problem. All it did was make the high side pressure higher and the low side lower. They tried adjusting them, but it didn't change the superheat or anything. They then suspected that when they put in the txvs, they overheated the powerheads (there wasn't enough room to remove them.) The unit was still icing up just back to the txvs.

They replaced the powerheads on both, but that didn't help anything either. They are completely stumped now.

Also, even though the high side pressure is about 300psi, the sightglass just shows a small amount going through, like a river. I'm not as experienced as they are, but it sounds to me like a kink in the line before or after the condenser, or some kind of plug there.

Any ideas would be appreciated, thanks.

[Brian_UK]

High side of 300psi doesn't help when we don't know the refrigerant.

Does sound like a blockage as you suspect, a good look around is needed. Perhaps use a contact thermometer across the various components to help find it.

[MikeGardner]

Good idea on the thermometer, but half of the lines are behind a non removable table top. And I think its r404.

[Brian_UK]

Good idea on the thermometer, but half of the lines are behind a non removable table top. And I think its r404.

Well of course they are, does any designer ever think about maintenance.

[mikeref]

Hi MikeGardner, just a thought, maybe the cooler is on the wrong refrigerant? Worked on a small coldroom marked R404a, 350psi pressure and poor cooling, changed it to R134a now runs fine.

[lowcool]

blocked condenser pass or receiver inlet blockage has given me grief before.

[monkey spanners]

First thing i would check is the drier, don't know if it was changed at the same time as the txvs.
Put a schreader valve in just before the txv and see if you have the same 300psi there, it should be pretty near to the same pressure.

[FEISTY]

Check model number on compressor and see what it ***** it was designed for. Who makes unit. If True or Continental chances are compressor is r134. Definitely take temps before and after drier. All else fails, a 4 drawer is relatively small capacity. Evacuate, blow out with nitrogen, change drier, pull a " good " vacuum and recharge to specs. Make sure condenser coil is clean and fan motor works. If problem returns, come on back with information and you'll find help !! Good luck.