A Mystery Manitowoc -

[Poodle Head Mikey]

This is a Q unit, maybe 600 lb. Water-cooled head, ten years old.

The operators say: we find it not running in the morning. Bine is not full. We switch it off. We fill it with water from a pitcher. We turn it back on and it runs fine - making ice.

It's on well water. Recently I have replaced the clogged water inlet valve, installed new water filters and rack, and installed a 10 micron pre-filter for well sediment.

The condenser water is unfiltered but the head pressure is always normal. And I have never found it off on the manual-reset HP control.

In the summer they had water pressure problems when lots of people were flushing toilets. But now it is winter, the bar is very slow, hardly anyone uses the toilets, the pressure is steady, and I increased their well pump pressure from 45 to 60 lbs. besides.

Last Thursday I was there and the unit was off on "excess harvest time". It's is spotlessly clean inside but did take it's time dropping ice - more than two minutes. I sprayed the cube molds with silicone and it then dropped the ice Very soon into defrost.

Is there anything else I can do to speed up the ice dropping?

Turning the switch off and then back on resets any board faults. But I just got off the phone with the manager and she claims that simply turning it off and then on agan does not refil or restart the machine.

They say they can only make it re-start to make ice by adding water to the sump by hand.

That makes no sense to me. As I understand it; the control board's water fill function works solely based on power to the machine and the water level sensor - when the level falls: the water valve opens. When the water level touches the sensor: the water valve closes.

What the hell can filling the sump from a pitcher have to do with that?

Any ideas?

[yotaman16]

in my experience take what people have to say with a grain of salt...They will tell u what they want.. Personally i would pull the charge and weight it back in with new gas just to eliminate that aspect of it.. then see if the issue resumes

[hvacpope]

it needs a new board and I have one for sale

http://hvac-talk.com/vbb/showthread.php?t=155437

[fuzzyj]

check the dump valve, may be partly open, also check the water regulator on the condenser, low head pressure will cause long harvest times, as well as hpr valve.

[pecmsg]

Recheck the level of the machine. I had a customer redo some tiles in the kitchen and knocked the unit out of level. Water would hit the sump level probe every now and then and it would never refill. When enough frost built on the plate the curtain wouldn’t open. 3 or 4 times I had to go back.

[yotaman16]

Any one have that manitowoc bulliten about the new thumb screw.. maby the machine thinks the water tray is full and its not but when they pour water in and turn back on she goes to town i will search for it i dont remember the models affected.. sorry thats the s model machines just found it

[DoctorIce]

I have had three Manitowocs where the water fill light was constantly on as long as any wire longer than three inches was attached to the probe connection. The cheapest solution was to install a float valve as the PC cards are very expensive here. This would account for the sump fill solution by the customer.
An erratic board is not a rarity.

[Poodle Head Mikey]

On this unit the fill function and full light appear to work perfectly - when I am there.

If I short the probe to ground - the light comes on and the fill valve closes. If I take the jumper off - the light goes out and the fill valve opens.

Then when the water leverl comes up to touch the probe - the light comes on and the fill valve closes.

Just like clock work.

A few days later they call me with the same story as before.

[itsiceman]

Still banging your head with this one A bad toggle (or loose ground) switch can give you all kinds of erratic symptoms I found one by wiggling the wiring in the control panel. The toggle had a bad connection and would act up instantly (but I missed it for something else previously). Also for the times with no error code stored have you noticed if the front cover has an indentation around the toggle switch area. Some older ones would turn themselves off if the front cover was bumped ( The cover plastic was smooth )

[fuzzyj]

check the dump valve, may be partly open, also check the water regulator on the condenser, low head pressure will cause long harvest times, as well as hpr valve.

pecmsg is right, after thinking further about this, your problem is strictly water related. As pecmsg states, no water or little water in the sump= a small amount of ice on the evaporator, not enough to move the curtain during harvest, harvest times out, instead of resetting by way of the curtain x 10 = extended harvest trouble code.

[cjcargo]

Recheck the level of the machine. I had a customer redo some tiles in the kitchen and knocked the unit out of level. Water would hit the sump level probe every now and then and it would never refill. When enough frost built on the plate the curtain wouldn’t open. 3 or 4 times I had to go back.

I've had this happen to me also, now it's something I check often. I often tilt the level slightly forward to help with the ice harvest. A trick I learned from a older tech on a old worn out Scottsman.

[bob1420]

the code was long harvest at night water to cond colder lower head less hot gas to melt ice off of plate need to raise head pressure to get suctionto at least 90 psi

[Poodle Head Mikey]

That ocurred to me yesterday. Although the discharge line was above 160 I thought the same thing. So I raised the head pressure to 300 lbs.

And, as the run is long to get fresh well water, I thought that maybe each time I get to see the machine it is using "pipe water" which is warmer, rather than "well water" which is colder.

Then, after a while, I leave, the well water shows up, the water temp is less, and the head pressure lower.

But wouldn't the cond. water valve compensate for that? Controling the head pressure at the valve's set-point?