Carrier Aquasnap won't restart

[elvis66]

I have a Carrier Aquasnap M#30RAN030A that won't restart after it shuts down on set point. I get no alarms and general ops look good. No safeties are tripped and system seems to be configured properly.

If I power down the control circuit, system will start and run until it shuts off on set point and then won't restart.

We just recently had all the sensors calibrated by our in house calibration/metrology department and am wondering if it might be possible that they may have damaged something on the MBB.

Yesterday I was getting operating modes 7, 8 and 9 on and 26 on but pressures and ops all very good. Checked this morning and it is off. Operating mode 9 and 26 are on.

All readings have been from the Navigator, but will be verifing with gauges and meters as soon as I finish this.

EB Ward tech support was not very helpful yesterday but will be calling them again today. They said that the MBB is in a "protection mode".

The space sensor is not hooked up and reads -40, but the unit was working fine before calibration with that sensor not installed, this is actually the first problem we have had with this unit since installation (Dec 2002) and has been the lag chiller since the calibration in January.

I will have more information later today, but was hoping that someone could get me started in the right direction if this is a control board issue or if anyone has had this problem in the past...

Thanks...

[djken]

Mode 26 is the one keeping the unit off. Look at your load and more importantly your loop volume. For that unit it needs to be at approx. 120 gals.Mode 26 is applied to keep the compressors from short cycling.

[licensed to chill]

Why were they calibrating sensors on the chiller. Either they are good or bad.
All the differnt modes(7,8,9,26 ) point toward low water flow.

Hope the "CALIBRATION DEPT" did not calibrate valves ,actuators,controllers and screw everything up in the whole bldg.

[jrbenny]

Mode 26 is the one keeping the unit off. Look at your load and more importantly your loop volume. For that unit it needs to be at approx. 120 gals.Mode 26 is applied to keep the compressors from short cycling.

Yep.

Step 1: Read the Controls, S/U, Op, and TS manual regarding Operating Modes.

Step 2: Read the Product Data with regards to required loop size and water flow.

Step 3: Apply what you read. You will fix the problem by simply reading the manuals for that chiller.

[elvis66]

Calibration was for loop temp verification as we are under FDA guidelines and it is required. The closed loop is for cooling of our production machines, not for comfort cooling.

I read the manual, and everything checked fine...based on Navigator readings. This chiller has worked flawlessly for the past 3 to 4 years and there has been no change to the closed loop, no repairs, no additions, no flow reductions, no machines down...nothing.

I went through all set up parameters, as we have to document all settings because it is a "Validated" machine, and all settings were as they have been for the past 4 years.

While running, all pressures were good and no reason to believe that the compressors would or could short cycle. Unit was calling for 35%-50% capacity until it shut off on set point and never even called for compressor 2/3rd and 4th stage. The unit ran for aprrox 20 minutes before it achieved set point.

Anyway, yesterday morning I plugged in the Navigator to do more troubleshooting and just about the same time, the unit kicked on and has been working perfect.

So for now I will chalk this up to a software glitch or stuck relay or something in the MBB because I can not duplicate the problem now.

Thanks for all the input.

[madhat]

This sounds a lot like what I call the, "Carrier Sleeping Chiller Syndrome" The chiller satisfies its load, the EEV goes fully closed and the chiller shuts off. On restart the EEV is not shown at 0%, instead it is being read at somewhere arond 98% even though it is fully closed. turning the unit off and on causes the unit to "jog" all its controls. The EEV reads 0%, and the unit restarts.

[djken]

This sounds a lot like what I call the, "Carrier Sleeping Chiller Syndrome" The chiller satisfies its load, the EEV goes fully closed and the chiller shuts off. On restart the EEV is not shown at 0%, instead it is being read at somewhere arond 98% even though it is fully closed. turning the unit off and on causes the unit to "jog" all its controls. The EEV reads 0%, and the unit restarts.

This unit doesn't have an EEV.

[elvis66]

Correct, no EEV, and Chiller is still working flawlessly...maybe it was just mad at me for having it in 2nd position for a month and a half and it was just paying me back...BASTARD...maybe I should put it back to teach it a lesson...ha ha...

[davemaldo]

I had a 15 ton aqua snap board go bad. everything read okay but the chiller would just not restart. after replacing and configuring the MMB It worked beautifully.

[maggio]

I had a 15 ton aqua snap board go bad. everything read okay but the chiller would just not restart. after replacing and configuring the MMB It worked beautifully.

have you had any problems with TO-77 alarms?