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Only S-series have the air pump on the back and not all s-series have them.

Manitowoc evaporators need to be Verticle.

I have had some do the same thing and I have had to change out the HPR valve. Do what Ice told you. Good luck

You need to check the discharge line temperture of the compressor. It should get over 140F during the freeze cycle. If it does not something is flooding back the compressor and taking all the heat out of it during freeze. With all that heat gone you dont have enough heat to harvest.

Is it possible you have an expansion valve problem ? I have seen machines that freeze perfectly but will not harvest due to an expansion valve that is not sealing off tight during the harvest mode causing a dilution of the hot gas. I would consider replacement of the expansion valve as well as the HPR and a solenoid rebuild kit in the hot gas line.

that machine has to have a head pressur regulater in the remote unit that holds it to 180 psi high side with correct charge of HP81 the psi should be 210 at that ambiet on high side if this is ok pull out charge do a 4 way pull on recovery .during harvest the hot gas stored in the reciver is all used in harvest if it is low it will do what you described.I hope this helps. the co I work for has 47 maitwocs models G,Q&S

If I didn't miss anything on this.. I would say a 10 min. freeze cycle is good. Your problem is in harvest. I have seen where the hot gas valve will open but not put enough hot gas through the evap to harvest the ice. Discharge line should be 165 degrees to get proper harvest of a Q model machine. Just an educated guess if I didn't miss anything in the posts.

So, can all the above be good and I still have separation?

Yes you can have good freezing, but bad harvest with this condition.

The last option is to as others said is tilt the head forward to assist. (until you get a new plate which i would first remove the plate to confirm the seperation)

I have seen this on maybe 5 machines in my 13 years. I would not try to increase the hot gas pressure as it is within the mfg specs.

Originally posted by icemeister

Originally posted by fridg
...make sure the plate is on an angle so the block can slide straight off in to the bin.

Could you expand on that statement?

Do you mean tilt the evaporator forward slightly from the vertical as a means to "assist" the ice sheet to release from the plate?

Yes tilt the plate on an angle from the bottom angling the top of the plate backwards.

This helps when the machine goes into hot gas the block slides off the plate easily.

Originally posted by icemeister

Originally posted by fridg
...make sure the plate is on an angle so the block can slide straight off in to the bin.

Could you expand on that statement?

Do you mean tilt the evaporator forward slightly from the vertical as a means to "assist" the ice sheet to release from the plate?

That is way funny!!! I had a call a few weeks ago. It was a new account. The complaint was slow production. I found an old manitowoc with chunks of OSB stuck under the back of the machine between the head and the bin. Harvest assist?

I had the self-same problem, and tried all the same solutions without success.
Turned out to be hairline cracks between the backplate of the evap, and the walls of the cube mould where they join the backplate. The ice clung in the cracks, and wouldn't drop unless I forced an additional harvest cycle each time. Didn't see them at first, but with a good light and a magnifying glass, there they were.
Tried brazing the cracks without success - the tin (or whatever they use to seal the join) wouldn't let the braze stick.
I've still got the evaporator in the shop - had to fit a new one. Anyone know how to fix the old one?

Originally posted by fridg
...make sure the plate is on an angle so the block can slide straight off in to the bin.

Could you expand on that statement?

Do you mean tilt the evaporator forward slightly from the vertical as a means to "assist" the ice sheet to release from the plate?

Another thing to check is

make sure the plate is on an angle so the block can slide straight off in to the bin.

I'd go with Icemeister then, good advice from a seasoned pro.

Originally posted by hvac_czar
Machine level?

I'm a basic kind of guy.

The sheet's not loosening. I can pull the bottom half out. The top is still stuck from about halfway - up.
And is does drop when I pass gas to the HG loop. All cubes are fully formed in the back too. Not like it's sitting there melting during harvest.

Machine level?

I'm a basic kind of guy.

Ice, i have seen it on the newer plates, just the very wide plates with alot of expansion room.

It seems to start in the top left, second row from the top and expand. This is the only reason for the defrost problem if the evap and pressures are good, you do not need to re-engineer the thing!

The older Manitowocs had separation ills to be sure. If the tubes are separated to any degree, this condition will indeed hinder proper harvest but will usually show up as an uneven freeze pattern. The tubes about two-thirds of the way up tend to go first, then the bottom tubes. You would see these areas freeze more slowly, often mostly filling in near the end of freeze.

If you suspect tube separation, (I don't at this point) you can remove the evaporator mounting screws on both ends on the evap assembly and gingerly pull it away from the bulkhead slightly and inspect the tube condition with a bright light and a long flat bladed screwdriver.

I haven't seen any of the newer alloy plated evaps separate, just a lot that will never consistently drop within 3.5 minutes no matter what you do to the rest of the system. Only a new evaporator cures these machines' ailment. Most every customer goes for a new machine at that point.

Thanks Freeze. But I wonder.

Freeze time is real good. Freeze pressures are real good.
Ice sheet looks real good - uniform top and bottom.

So, can all the above be good and I still have separation?
I'm asking because I don't know. I've never seen a plate separate.

I think you will find the copper tubes pulled away from the back of the evap not allowing good contact between the how gas lines and the plate. Manitowoc had alot of ploblems with certain machines in that ERA!