View Full Version : Old Carrier Aquasnap - intermittent fault code 34.

19-05-2017, 01:48 PM

Apparently code 34 is either HP not reset or circuit A compressor reverse rotation.
HP had not tripped, reset fault & both comps on circuit A run normally - how does the Pro Dialog determine reverse rotation? There is no phase rotation module, other forums suggest it is 50psi pressure differential within 10 seconds - any additional information or insight greatly appreciated!

HP pressure transducer is in calibration, LP approx 0.4 bar low - could this be failing? All connections look good on transducers & PCB.

Many thanks in advance.

19-05-2017, 10:32 PM
The A series alarm 34 doubles up with HP and phase reversal. The B series gives each fault it's own alarm 33 for HP and 34 for phase reversal.
The phase reversal is done when the Pro Dialog sees no increase in pressure when the compressor starts. Does the compressor run ?

20-05-2017, 07:45 AM
Thanks for the reply Gibbo-
This is an A series - both compressors run without issue, every time I'm on site. They do have soft staters but I have no reason to suspect them, no volt drop across contactors, all terminals tight, run current reasonably balanced & stable etc.

Carrier tech say say there is a Pro Dialog firmware revision that can help with this issue, so I wonder if it's a known problem. They originally suspected poor continuities through the HP, but it's been replaced twice already to my knowledge- the last time only two weeks ago.

Were probably going to get Carrier to site, fit a new control PCB, flash the recommended firmware, and check operation with the laptop connected, just to reassure the client if nothing else. This intermittent fault has plagued this site (and me) for years!!

20-05-2017, 10:32 AM
Hi Laf.
I doubt it is relevant.
But I happened to be on a site once where the Maintenance Companies Engineer was onsite at the same time as Me.
We got chatting and He explained a similar intermittent fault.
Only on this one the whole switch room control panels would flash on and off.
With the Carriers showing the same alarms.

Call Me lucky, but later I was looking at the chilled water circuit pressurisation unit which was just at its set point pressure wise (Say 1.5 Bar.)
When this light display commenced! (Controls flashing on and off)

What transpired was the pressurisation unit on the chilled water circuit had virtually no set point differential.
So the pressurisation unit would randomly, violently switch on and off. causing the flow alarm to pulse.

The Aquasnap controlled Chillers would go into alarm. But the waterflow alarm was not the one that tripped. Widening the mechanical switches switch differential solved the problem.

A lot of manufactures electronic control systems when tripped on and off rapidly will trip on an alarm within the
chronological order of the programmed alarm settings.
You appear to have covered all the usual suspect already, so good luck and I hope the issue is resolved for you.

20-05-2017, 11:13 AM
There is a software update which included a fix for nuisance trips on aquasnaps pre 2004 amongst other fixes.
Regarding the phase reversal. The controller has to see a minimum of 1 bar differential between high and low pressures within a few seconds otherwise it thinks reversed compressor rotation.

20-05-2017, 09:03 PM
Many thanks Grizzly - but equipment is in a private property that has several alarm systems that (allegedly) sound if there is the slightest power cut/dip/surge etc.

Gibbo - that's what I'm hoping will see this one finally put to bed!