Low Pressure Alarm on AC Unit (290 Dancer)

[Bateau Ivre]

The platform is a 2000 290 Sundancer. Upon entering the winter season and switching the AC unit from cool to heat I began having a low pressure alarm. I have done on the usual checks, cleaned the strainer (again and again), ensured the hose clamps are tight all around, blew air through the system from strainer thru ac unit out exit drain and ensure that I have good water flow through the seacock. I have to assume that I don't have any air leaks since the system has to be primed. I leave the boat in the water year around (South Carolina) with exception of pulling for general maintenance.
There is water flow out of the exit fitting but not at the rate that I think it should be as it appears that a brisk wind will interrupt the stream (i.e. low pressure). One item I noted was a sharp bend and kink in the hose at the entrance of the AC unit in the cabin behind the steps. I assumed that this was causing a restriction and replaced a section of the hose and ensured proper bend radii of all hose lines. This did not correct the problem. I did note in the hose section that I replaced was some sediment that was clinging to the sides. Was thinking that the impeller in the circulation pump might be munged up. Before I replace the circulation pump (about $200), I was wondering if anyone has had a similar problem or any suggestions.
Thanks/Dave

 

[Four Suns]

Since I don't know your location other than South Carolina, I don't know if you are in salt water or fresh water. If you are in salt water, have you ever had the system flushed with acid? The lovely little barnacles will grow inside the entire system and it has to be flushed from time to time to keep the heat exchangers clean and clog free.

I use Rydlyme ( http://www.rydlyme.com ) on my system once a year and it works really well. You'll need to build a flush kit also. Dominic is the king of that. Rydlyme works great on the engines as well.

 

[Bateau Ivre]

Charleston is the location and the boat sits in a mixture of fresh and salt (bracish). I have not flushed the system with any type of acidic solution other than fresh water. Thanks, I will give it a try.

 

[Four Suns]

If you don't want to DIY on this... You can probably call a service company in your area to do it. Check around at your dock and see what other people do.

 

[mooredriven]

I've had a similar issue, however, I am on a fresh water lake. It's seems to pop up more in the summer months than winter. It has never occurred when we are on the boat. Only after we have left for more than a week.

For winter, I've now switched to a ceramic heater to eliminate any potential for it shutting off, other than loss of power.

Dale

 

[Hampton]

I was told a trick which seems to work. Get a Chlorine tablet used to keep pools chlorinated. Break it up into small chunks. Put them in your strainer. Turn the system on to whatever mode will keep the pump operating continuously for 2 days. It will flush the system and kill any growth. Do not let the tabs sit idle in the metal strainer. The chlorine will erode it.

 

[Skip]

I also had a LO PS error code in my 420DA this fall. Low freon was the culprit. CruisAir rep came out and charged the system and that took care of the issue.

regards
Skip

 

[Four Suns]

A LO/PS error code typically means low freon or the water is too cold to use the heater. A HI/PS error code means no water flow if the AC is being used... but he said he had no water flow from visual inspection so that's why I said to look at flushing the system. It is possible to get a LO/PS error code in heater mode if the lines are restricted and the water in the heat exchanger gets cold from restricted water flow... if that makes sense. The heat being is being extracted out of the water faster than it can get more water to extract heat.

In addition to those error codes, I've also had the LO/AC error code which happens when there is not enough juice at the dock and there is only like 200 volts available which happens on the end of the dock T head on 110 degree days.... but I digress....

 

[Bateau Ivre]

Problem solved. Long story version. I disconnected all of the associated water lines. Ran a 1/2inch snake through each of them and then flushed all lines with fresh water. Lots of silt and muck. As noted previously, I did replace a section at the input to the ac unit as it was kinked due to bend radius. With all of that complete, still had a low pressure alarm. Checked the freon pressure levels and it was in fact low as "Skip" mentioned. Added a bit of R22 to the system setting the correct hi and low pressure levels and voila, success. The techinical documentation for the AC Unit doesn't mention this as a possible resolution. I most likely had the same proplem in the summer months but with the drop in temperature relates to a drop in pressure as well. Oh, by the way, checked for freon leaks with a sniffer and wasn't able to detect anything at the coils, capilary tube, compressor connections or in the drain base. Might have a leak that is being discharged out of the waterflow system. I will continue to monitor and provide updates. I appreciate the feedback from all. As a side note, I don't recommend using alternate heating sources (i.e. ceramic heater, etc. - "mooredriven") as this has the potential of causing a fire shipboard if unit is knocked over or fails. I would recommend that you contact your dealer and have your system checked by a reputable source as it should work as designed. Again thanks for the comments.

 

[bahamabreisus]

Glad your problem is solved. We live on our 500 DA in Wilmington NC. (salt water). We have constant barnacle issues in our system. Flushing the system with a garden hose monthly keeps the system fairly clear, but we do use acid every other month. Some of you that have the red A/C pumps, they are magnetic drive. If you remove the discharge housing, and clean the magnets, the water flow will increase greatly. This is helpfull in both fresh and salt water.

 

[Robski97]

Guys ,
When charging the unit u cant be in heat pump mode. Also a clogged condensor in heat pump mode is like a dirty filter in a/c mode. Also water temp is a huge factor . Charging a water cooled unit with low water temps will casue u to overcharge the unit. So just keep an eye on it in the spring and summer. Its best to use a amp meter while charging as well . once u reach the FLA of the compressor only stop charging!!!

Rob

 

[jg300da]

Also, adding refrigerant only solves the problem temporarily. The leak needs to be found and fixed.