Hoshizaki Ice Machine

[280zx]

Hoshizaki KML-451MAH off from 2 consecutive max freeze cycles (3beeps). Reset and machine makes a good batch of ice with a 40 min freeze cycle. Thought this to be a bit long for the conditions.

Water temp: 55 degrees
Ambient temp: 66 degrees

Performance data for this machine under these conditions is about 23-24 min freeze cycle.

Machine including condenser is very clean. Verified water inlet does not leak by and that float switch does not stick. Pump is supplying adequate water to header. Line after HGV is about room temp (65-70 degrees)

Here is where I'm finding issues...
Coming out of harvest and for about 3 min into freeze, the txv makes a god awful moaning sound unlike I've never heard one make. I put gauges on, and measure this 5 min into freeze as recommended by hoshizaki...

Head pressure 195 (404A) performance specs say it should be around 218.

Suction is 60 and performance specs state it should be 45.

I'm getting a little over .50 to 1 degree superheat out of evap by sensing bulb which is tightly secured and insulated. About 25 min into freeze the compressor body is icing up and feels very cold.

Amp draw is 7 when rated for 7.9

I am reluctant to condemn a txv for flooding since I know this isnt too common and it does produce a good batch of ice (although long freeze imo),but to me all my signs are pointing to this.

I'll take any insight.

Thanks

[UmmScott]

One way to find out...pull the charge and put in the exact factory amount....if same then sounds like a flooding txv beings as u have frost on the comp.
Do an amp performance check to rule out the compressor

[2sac]

Is the noise coming from the txv itself or the refrigerant? Txv's are supposed to be quiet:grin2:

[harwar]

Seems like the compressor to me. High suction, low head pressure. If was just an overfeeding txv I would expect high head pressure as well. That would explain the low production but not the noisy valve. Probably a good idea to replace it while you have the system open.

[pecmsg]

Compared to the chart how are the pressures 5 min into freeze & coming out of defrost?
Has anyone added refrigerant that you know of? (May have to pull and weigh charge)
Compressor frosting near end of freeze may be normal.

[UmmScott]

Seems like the compressor to me. High suction, low head pressure. If was just an overfeeding txv I would expect high head pressure as well. That would explain the low production but not the noisy valve. Probably a good idea to replace it while you have the system open.
Idk bout that....I don't think a weak compressor would present flooding back

[JWB]

remove bulb and warm and chill it, looking for pressure changes. is the evap getting cold quick or slow? that will tell you about the state of the refrigerant.

my friend and I were having a similar conversation today about ice machine......will a low charge make the suction pressure higher 5 minutes in because the water and plate is actually warmer? I rarely put the gauges on....so it made me stop and think........

[coolperfect]

Block the condenser a little at time,see what happens!

[UmmScott]

remove bulb and warm and chill it, looking for pressure changes. is the evap getting cold quick or slow? that will tell you about the state of the refrigerant.

my friend and I were having a similar conversation today about ice machine......will a low charge make the suction pressure higher 5 minutes in because the water and plate is actually warmer? I rarely put the gauges on....so it made me stop and think........
I've seen when machines are only slightly low, the suction won't drop cuz the txv is trying to maintain superheat.
But as it loses further charge the suction would eventually become low

[Ajbriz]

Easy to check compressor. Unplug the water pump and watch your suction pressure drop As the evap freezes. Also check to make sure the stainless plates of evap are not broken loose from the lines. I have seen several come apart due to freeze ups.

[sammyray]

This is what flooding TXV looks like on Hoshizaki

[280zx]

Replaced with factory expansion valve and new drier, now machine is following performance chart. Weight refrigerant as I was recovering and the charge was correct. Freeze cycle went from 40 min to 20 as should be.

The reason I discounted bad valves is because, (in my experience) bad valves can causes higher superheat due to the decrease in pumping capacity, not flooding. I think I nailed it ...pressures, superheat and freeze time are night and day now.

[UmmScott]

Replaced with factory expansion valve and new drier, now machine is following performance chart. Weight refrigerant as I was recovering and the charge was correct. Freeze cycle went from 40 min to 20 as should be.

The reason I discounted bad valves is because, (in my experience) bad valves can causes higher superheat due to the decrease in pumping capacity, not flooding. I think I nailed it ...pressures, superheat and freeze time are night and day now.
Yup....if the comp is sweating like a pig, then I'd be more suspect to checking charge level and metering device function

Good job man

[yaytech]

I guess that moaning txv was trying to tell ya something there doc...

[btglow2894]

Hoshizaki KML-451MAH off from 2 consecutive max freeze cycles (3beeps). Reset and machine makes a good batch of ice with a 40 min freeze cycle. Thought this to be a bit long for the conditions.

Water temp: 55 degrees
Ambient temp: 66 degrees

Performance data for this machine under these conditions is about 23-24 min freeze cycle.

Machine including condenser is very clean. Verified water inlet does not leak by and that float switch does not stick. Pump is supplying adequate water to header. Line after HGV is about room temp (65-70 degrees)

Here is where I'm finding issues...
Coming out of harvest and for about 3 min into freeze, the txv makes a god awful moaning sound unlike I've never heard one make. I put gauges on, and measure this 5 min into freeze as recommended by hoshizaki...

Head pressure 195 (404A) performance specs say it should be around 218.

Suction is 60 and performance specs state it should be 45.

I'm getting a little over .50 to 1 degree superheat out of evap by sensing bulb which is tightly secured and insulated. About 25 min into freeze the compressor body is icing up and feels very cold.

Amp draw is 7 when rated for 7.9

I am reluctant to condemn a txv for flooding since I know this isnt too common and it does produce a good batch of ice (although long freeze imo),but to me all my signs are pointing to this.

I'll take any insight.

Thanks

Ive had the same thing happen to me before. Pressures were all weird, unit took about 10-15 before it started forming ice on evap. Then after 25-30 ice was forming on comp. The unit had a bad txv, changed it and.worked.great after