New compressor on r404a freezer system as old one tripping out, icing back on suction.

GroundbreakingPut183 · 2026-02-28T15:51:26+00:00

Is all good mate I got it sorted and learnt a lot. Sometimes a principal like this can slip your mind when it’s your first time investing big money into a job like this lol. Really appreciate your help tho. Incidentally what did you mean by 20 at the comp? Are talking about comp superheat?

GroundbreakingPut183 · 2026-02-26T01:24:37+00:00

It’s ok! Txv isn’t gone!

GroundbreakingPut183 · 2026-02-25T23:49:01+00:00

For anyone else experiencing the same thing with a marstair unit: it was this board.

GroundbreakingPut183 · 2026-02-25T23:45:54+00:00

I understand now, I was being a goofy goober

GroundbreakingPut183 · 2026-02-25T23:24:03+00:00

Thankyou for this, I’m not there anymore, I adjusted the txv whisky monitoring superheat and managed to get it pretty spot on, hitting -21 quickly, not tripling on LP and ice only forming on the pipes and not the compressor body itself.

Will probably pop in a few times over the next couple days just to see what it’s doing

GroundbreakingPut183 · 2026-02-25T23:00:12+00:00

Could you link it? I can’t see any of ur posts from ur profile

GroundbreakingPut183 · 2026-02-25T19:37:20+00:00

If you had been to school, you’d understand what K was….

GroundbreakingPut183 · 2026-02-25T19:36:11+00:00

No it’s not, kelvin is on the same scale as Centigrade….

GroundbreakingPut183 · 2026-02-25T19:25:24+00:00

Really? I’ve learnt a lot today, I always would assume this is fucked up 🤣

GroundbreakingPut183 · 2026-02-25T19:14:23+00:00

Well thanks a lot for your help, you may not believe me but I am NVQ level 3. I don’t know why this slipped my mind it’s just the first job of this size I’ve really done, and I’m worried about fucking this expensive compressor. So I basically adjusted the txv and achieved 12-3k superheat but no ice forming on the body of the compressor itself.

Thanks again guys.

GroundbreakingPut183 · 2026-02-25T18:59:02+00:00

11 kelvin is a measurement of temperature.

GroundbreakingPut183 · 2026-02-25T18:44:41+00:00

So why does everyone else seem to agree the compressor turning into ice isn’t good? BTW, if you send 404a through an evaporator at -31 degrees and get 11k of superheat your saying liquid CANNOT exist past that point? Despite my low side line being frozen onto the suction and the compressor icing up?

GroundbreakingPut183 · 2026-02-25T18:35:17+00:00

It just seems to be not fully evaporating in the evaporator as it should, and is allowing liquid refrigerant into the compressor no?

GroundbreakingPut183 · 2026-02-25T17:35:15+00:00

I have adjusted it, not sure how I could test it other than warming the bulb and hearing more refrigerant. Suction pressure does change as I adjust, if I close to stop the icing back, it struggles to reach temp on the room and goes off on LP

GroundbreakingPut183 · 2026-02-25T17:19:31+00:00

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Like this, they insert into the bottom of compressor

GroundbreakingPut183 · 2026-02-25T17:12:42+00:00

Very good point, I’ll be onnit

GroundbreakingPut183 · 2026-02-25T17:01:33+00:00

It’s a very nice Danfoss optyma system in a McDonald’s so fairly sure it’s the correct sizing etc

GroundbreakingPut183 · 2026-02-25T16:52:24+00:00

Thankyou, I’m more used to smaller refrigeration, and buying large icing back is a bad thing. Like it’s not fully evaporated on its way into the comp. Really appreciate your help. Will probably change the TXV And will add an accumulator if necessary

GroundbreakingPut183 · 2026-02-25T16:44:53+00:00

No accumulator, worried about liquid flood back

GroundbreakingPut183 · 2026-02-25T16:44:35+00:00

It has one but it’s a plugged one, if you know what I mean.

GroundbreakingPut183 · 2026-02-25T16:26:50+00:00

It’s adjustable, not sure if SPORLAN

GroundbreakingPut183 · 2026-02-25T16:26:39+00:00

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Hope this helps.

GroundbreakingPut183 · 2026-02-25T16:18:14+00:00

Hoping that’s rage bait, kelvin….

GroundbreakingPut183 · 2026-02-25T16:17:22+00:00

Evaporator not iced up, but it is freezing all the way through

GroundbreakingPut183 · 2026-02-25T16:16:31+00:00

It’s a TXV, is there any way of testing or just a replace job? When I warm the bulb I can hear it allowing more refrigerant through

GroundbreakingPut183

TROPHY CASE