First off...hoshis don't have a coating they're stainless steel.
2nd step is a clean machine...make sure there's no scale and lime on the evap.
3rd if he pays u and is willing to fix it...there's more steps u can take and tests you can do.
Let us know

 

Usually Hoshizaki harvest problems are related to water inlet flow. The hot gas only "ASSISTS" the harvest - there is way too much evaporator to warm up with only hot gas. The entering water warms the plates for harvest. Check water filters/water supply.

What style machine are you working on? A crescent cuber we presume.

 

it is that little thin cuber one, if the water filter or water flow is not right, how would the evaporator freeze over all the way than; are you thinking that there is not enough water flowing to harvest it, and have you heard of this coating thing, guy wanted to change entire evaporator and i said i would have to find out myself, i am more familiar with manitowac than hoshizaki so i appreciate the help. So when it goes into defrost, water flows across the evap, hot gas flows in and than the cubes start to fall for a good minute or so is how I think it works. Where exactly would you start with this unit if you were on the job

 

You really need to give us a little more information.
In the meantime download the service manual for that model and get more knowledge.

 

little thin cuber one? What is the model number?

The crescent cubers are stainless steel - no coating. I don't think we know what you are working on.

 

Manitowoc for instance, is nickle coated copper. The nickle is what the guy is talking about. I have in the past once used food grade silicone on an ice machine evaporator that had lost it's nickle plating.

 

Check for sufficient supply water... plugged inlet screen, filters, undersized lines scaling.

If the condenser water valve keeps flowing thru harvest the hot gas is reduced.

Oversized, ridged cubes can slow the harvest.

 

When it goes into defrost - assuming it is a crescent cuber, I am not sure - the water enters BETWEEN the evaporator plates that are back-to-back. the water flowing at the back of the plates warms the evaporator to release the formed ice.

If the machine goes into harvest and some oof the ice does not release (usually at the bottom of the evaporator), the ice will log jam between the plates and start freezing into an iceberg. Then it's all downhill from there. Hoshi also specifies the minimum water temperature to serve the machine to assure good harvest. If the water is too cold, the plates are not warmed enough to release all the ice. If the water flow is low, not enough volume / flow rate of water is realized to assure all the ice gets released. During winter months and colder water supply temps, harvests take longer or can fail altogether.

 

checking to assure the water distributor is clean and not restricted is another thing to consider. Some holes in the water inlet distributor may be plugged and cause poor water flow / evaporator warming in affected sections of the ice making surface.

 

I have found when you have a harvest problem on a Hoshi KM, first pop off the top-

Pull the distribution tube, funnels, and fill tube- are they clean?

Look down thru the evaporator and check for scaling- (most likely the problem)

Pull on the evaporator ice sheets and see if there is any separation from the coils-

If all is good- check water flow- if it is poor see if there is a plugged pre-filter, and there is also an inlet screen on the fill valve that can restrict flow.

For the OP, silicone spray is a temporary fix on any machine, and if it is not food safe the health dept could be all over your a$$.

 

Listen to IRBH.
A leaking water valve on a water cooled unit will not allow the head pressure to climb and it will not drop ice.

 

make sure it is clean scale will not let the ice drop

 

If you can shut off water to condeser only see how it harvest had that a while back. Seat was wore

 

A hotel with 14 water cooled units. Every one would not harvest. Great ice, but not dropping. 14 water valve rebuilds later there were 14 full ice bins.

 

Wow

 

Just for everyone's curiosity, the hot gas harvest cycle on a Hoshizaki KM machine is assisted by the inlet water, not the other way around. It is just semantics, but I think it is interesting to understand. Stainless steel is a terrible conductor of heat. It is this very property that helps form the shape of KM cubes. The addition of inlet water between the plates during harvest is primarily just to help spread the heat from the hot gas more evenly through the evaporator.

 

^^ Well said.

 

Well I thought I would post the problem for you all I found right away once I put my gauges on unit. The unit is water cooled and the regulator was not regulating, my condensing temp was 65 deg, now unit is working good, only problem I see is that the defrost is lasting an entire 8 min, even though the last 3 or 4 there is no ice left on the evap, i don't see what dip switches hoshizaki is talking about that give you longer defrost, what is the typical time for defrost on one of these machines

 

Cool...
And yeah like baub said, in the winter time your harvest is going to be longer due to colder water going thru the potable water to the machine...
Even worse in your case as you have a water cooled machine...and if u have water going thru that condenser during harvest, then there goes all your heat....down the drain literally.
That valve has to close during harvest

 

You never posted the mod number of your machine, so I'm guessing it is a 404-A machine with an E board. The machine goes into harvest and stays in this mode until the suction line thermistor reaches 45 deg, then the timer is initiated. The time is adjusted by dip switches 1 and 2. Without knowing the model, the length of the timed section is an unknown.

One thing to note- if you are in cold winter country, you have to have a long harvest cycle, (up to 180 sec.) because cold incoming water slows the harvest time.

Check the handbook for your particular machine... it's all on the Hoshi site.

 

typically if you have a"g" board water assist during harvest last for the first 6 minutes or until the thermistor reaches 48 degrees
when the thermistor reaches 48 degrees the timer( which is adjustable) on the board will keep hot gas flowing for set time
cold inlet water will usually cause full 6 minute time period then timer takes over could last 8-10 minutes total