This is just a note to confirm that I offer FREE Troubleshooting help for your Marine A/C & Refrigeration issues…But I ONLY do this in the FORUM section…If you can’t take the time to register & ask in the FORUM…I usually won’t respond…(this section is not setup for dialog/discussion…it’s only setup for comments)

My only request in return is that you Consider me when buying replacement parts, or units…And that if local, you also consider my services….But how’s they saying go ?

No Purchase Necessary…That price can’t be beat at half the cost !!!

All you need to do is join & ask in the FORUM section most relative to your issue  http://marine-ac.com/forum/

Post your own title (thread) in the section that applies, and I’ll be happy to respond with my best honest advise…

Thanks Again,

Steve~

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Due to new 2010 EPA regulations regarding the phase out of our long used R-22 A/C refrigerant systems…

Here’s what I can share at this point from the Cruisair/Marine Air perspective & what I have been told.

Self Contained R-22 units are no longer in production…sort of…

Since 417a is a drop in replacement for R-22 you can get the R-22 units (but they are shipping charged with R-417a)

We are told that the R-417a drop in replacement refrigerant for R-22 is 17% less efficient than the R-22 in the same unit (like running 60Hz equipment on 50Hz power)

So if you bought a new R-417a unit…You can evacuate the R-417a and re-charge that unit with R-22 to realize the same performance as a R-22 unit that was purchased before the production change…

You can also evacuate a older R-22 system & recharge with 417a…But the 17% performance drop still applies…

R-22 refrigerant should still be available for quite some time yet…But…The price will climb pretty quickly.

The new R-410a cannot be used in a R-22/R417a system even with evacuation…It’s not compatible with the oil in the 22 system & the pressures will run too high in that system (metering devise is not set for it either)

My distributor has about 3 months worth of sales of units with R-22 available, but after they are gone he will only stock the new R-410a units….And is now only ordering Self Contained unit with the new R410a.

Split or Remote systems are a whole different story…

One thing they are the same in is that none of the existing systems can run the new R-410a, but they can run the R-417a with the 17% drop in performance….but the problem is bigger with small split systems.

Typically the 16K & smaller split systems have always used piston type compressors as opposed to the rotary type that have been used in self contained units for many years now…

The reason for this is that the rotary type compressor does not lend itself well to long copper line runs…
Rotary crankcases don’t hold enough oil for the migration of oil with the refrigerant throughout the longer line runs in split systems…
It’s my understanding that the rotary can run out of oil before it has a chance to return with the refrigerant, and thus can ruin itself in a split system from lack of lubrication.

The compressor manufacturers are being forced to phase out production of the lower efficiency piston compressors by the EPA or whomever…

Scroll compressors would be a great alternative, but as of yet…The compressor manufacturers have not developed Scroll compressors in the smaller sizes that are required for our smaller Marine split systems (the larger than 16k marine units are using scrolls now)
I guess they figure the Marine market is too small to develop new small scrolls for, and that the rotary’s are fine for the home window unit market (which is what the the rotary’s were developed for)

I know that Dometic Cruisair/Marine Air has been testing small splits using rotary’s for quite some time now…So far they aren’t saying much…Hopefully we will get more info at the Miami show next month…

Until then…They are only offering the same piston type smaller split systems and shipping with R-417a (the drop in replacement for R-22) to meet the new regulations….The Larger splits (over 16K) will be available as either R-417a (mainly for replacements of the older R-22 units) or the new R-410a units, but to utilize R-410a condensing unit you must also change the air handler…No need for new copper tubing runs.

Who knows…We may end up not having split systems under 16K available in the future…

Steve~

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It’s the time of year that we all need heat…Even here in Florida this year…Global Warming My…?

Anyway…

Below is a post I answered in the Hatteras Owners Forum, and it seems to be a subject that many of you all are searching for answers to this time of year…It also applies to cooling in the summer, but is mostly about system Icing & the causes…I’m also going to  link this article to a Forum post here on this site so that anyone that may have questions or need further clarifications may ask away there… 

Quote:

Originally Posted by SeaWhisper Don’t mean to jump on this thread ! Steve if your following, I have been experiencing an a/c problem also but on the heat mode side. I have 4 A/C system with one giving me a icing problem on the compressor unit. Starting on the suction side and loop tubing of the remote unit is freezing up with heavy ice. The compressor is hot to touch. Check air handling unit… High fan, clean filter giving out warm air. Water flow thru compressor unit and 3 other unit’s has a high flow rate. Water temp is around low 50’s. I can switch the unit to cool mode and it will melt the ice of the compressor unit… Your thoughts on what may be causes the heavy icing…. Low freon? Unit is a 16,000 btu maybe 2 years old, with smxir controls. Thanks…

Mike~

First I need to clarify what you mean by…”Starting on the suction side and loop tubing of the remote unit is freezing up with heavy ice. ”

Do you mean the water coil ?

If so…Then it would be hard to know that the unit in question is actually getting proper water flow by looking over the side…Since all the 53 MY’s I can remember, had a single overboard discharge fitting with a 4 unit manifold attached.
You would need to remove the hose for the unit in question from that overboard manifold, and either let it run into the bilge or a bucket…It’s not uncommon to have a blockage or some kind of growth restricting one unit’s seawater flow….This can cause what you describe.

Yes the compressor will run a bit hotter in the heat mode…

Icing is always an indication of Low Pressure…What is causing that low pressure is key to solving it…Duh ?

First…Pressure & Temp correspond with refrigerants…The lower the pressure of the refrigerant…The lower the temp of that refrigerant…

If you place a jug of refrigerant in a room and connect a pressure gauge to it…then let it get to room temp by just sitting there…
With a pressure temp chart for that particular refrigerant (in this case R-22) you can tell the temp of the room by the pressure shown on the pressure gauge…If that room is 32*…The gauge will read somewhere around 56-58 psi. (the chart I have with me right now jumps from 30 to 35 degrees so I’m guessing a bit but that’s close)

When running in heat mode the water coil is the evaporator and is on the low side of the system (cold part) the air handler is the high side (hot part)

In cooling they switch duties because the Reversing Valve will send the refrigerant around the system in the opposite direction.

Thus a “Reverse Cycle” system also known as a Heat Pump…

Back to what I started saying about Icing being an indication of low pressure…

Air Conditioning is what we call a High Temp System…Designed evaporator temps above freezing (32*)…Therefore “Low Pressure” in a R-22 A/C system is defined as below that 58-56 psi I mentioned earlier…Which will cause icing by freezing any moisture that is in contact with that surface thus blocking flow…Either Air or Water (depending on which mode you are running in)

A/C (and refrigeration) is all about moving or removing heat, since there is no such thing as Cold…Just the absence of Heat…Making it feel Cold…

In the heat mode you are picking up heat from the water with the water coil and dumping it into the cabin, using the refrigerant as the truck to carry it, and the fan in the cabin to dump it out of the truck…Cooling is just the opposite, and uses the Cabin coil to load the truck with heat, and the water to dump it out.

Any restriction…Ice, Air Flow, Water flow etc…Will affect how much of that heat can be picked up by a designed size coil in both the heat & or cool modes.
This is why icing is not good with A/C…Refrigeration is another story since it usually has defrost timers & heaters…A/C does not, or should not need due to the temp range it was designed to operate in…with Above 32* evaporators.

The biggest problem with icing the water coil in heat mode is the danger of freezing the seawater in that coil & blocking flow completely…Thus causing expansion, and a rupture of that water coil…
This will allow the freon to leak out into the water, and the water to leak into the freon circuit, effectively ruining the complete system by pumping that seawater throughout the system with the compressor.

Low amount of freon causing icing ?…Yes this can also act the same as flow restriction…

Either way…Low freon, or Flow restriction…If the truck/s can’t get full for every circuit (restriction) or don’t start full (low freon) you are not moving the designed amount of heat that the system was made to transfer…Both of which will cause Low Pressure on the on the suspension of the trucks…

Back to:
Low pressure = Low temp = Icing…
Icing = Restriction = Less Flow = Lower Pressure…etc…etc…
One compounds another.

I know that was long guys…But I hope it helps in a lot of these questions…I know it can be confusing, or boring to read but it’s all part of understanding what is happening…
I tried to put it into the easiest layman’s terms I could think of…If you have any questions on what I said just ask & I will try to clear them up.

Steve~

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I notice from the Google searches…That A/C System Icing is a search done often..

Though there can be many reasons for system icing…There are a few that the DIY boater can rule out before calling the service guy ( I can discuss other reasons in the forum but here are a few of the basic answers)

• Direct Expansion A/C (as opposed to Chilled Water) systems rely heavily on Air Flow across the evaporator coil in order to pick up the designed amount of heat the system was engineered to remove (BTU) and any loss of that designed air flow can cause the system to Ice.

Regardless of freon charge (explained later) the system must first and foremost have the correct amount of air flow…So air flow should be the first thing to check…Below are some reasons for reduced air flow…

• Dirty or clogged Return Air Filters…Some systems may have two filters installed…One at the Return grill, and a second that shipped with the unit on the evaporator fins ( folks tend to forget this one, or never knew it was there in the first place)
• Dirty or clogged evaporator coil/s due to not cleaning, or No/Poor return air filters installed.
• Fan Speed Adjusted Too Low (Sometimes done to attain a quiet blower)
• Undersized Return or Supply Ducting for the BTU System installed…This was the installers responsibility to size correctly, but all too often there is not sufficient space for where they want to run to size it properly…Thus a problem for the systems life, which is most always shortened dramatically from this practice…They should find another way, or reduce the size of the system to match the installation…Blowers can only move rated flow thru the proper sized duct.

 Another reason which sometimes is overlooked…

• Very Cold Cabin…The colder the cabin…The less heat there is to pick up…Thus more Air Flow is needed to increase the amount of heat (that’s now not there) being picked up…A/C systems are called “High Temp” systems…they are designed to do exactly as the name implies…Air Condition…Not Refrigerate…That’s what Refrigerators & Freezers are designed to do…Your A/C system is not designed to cool much below 68 degrees F…Though it will try to do so if you ask it…
• Most of the newer Digital Cabin Controls have algorithms to “help” with this by shutting off the compressor for short periods until the desired room setpoint is attained, but they are not defrost cycles with coil heaters like you might find in a system designed to run at lower temps. 

Last but Not least is…

• Low Refrigerant Charge causes Icing…You Ask Huh ???…Why would low freon cause it to ice ?…I thought the more freon the colder…Not So with refrigerants…I’ll try to explain briefly…

Pressure & Temperature Automatically Correspond with Refrigerants…The Lower the Pressure…The Lower the Temperature of the refrigerant ( and Vise Verse) Regardless of how much is in there…I’ll leave it at that for now but can explain further in another article, or in the forum if requested.

• The question here is…Why is the system low on freon ???

These systems are sealed, and should not require seasonal charging, like automotive systems that tend to leak because they have rubber hoses, o-rings & compressor shaft seals…These systems are all copper tubing, with soldered & mechanical flare joints.

• Did someone let out freon because the unit was running high pressure ? (usually an indication of  loss of seawater flow, or a dirty condenser)
• Has the system started leaking due to a poor connection (Flare or otherwise) or maybe electrolysis eating away at solder joints ?

If So…Then the leak needs to be located & repaired to save burning up the compressor…The compressor is the heart of the system, it’s expensive, and relies on the proper amount of refrigerant return to stay cool…It will run Very Hot without enough Freon return regardless of seawater flow…and even if the system (air handler or tubing) is icing…The compressor will run hot from that lack of freon.

Hope this helps answer a few questions, but if not…Or if it creates more…Drop me a line (preferably in the forum so that others can benefit as well)  Always glad to answer.

Steve~

Everyone can access it, but registration is required to post…I don’t share that info…You can find the link at the top of any of Marine -AC.com’s pages…Just click on “Forum”…Or you can click on this http://marine-ac.com/forum/

We are slowly growing, and I seem to notice from the searches what folks do to find Marine-A/C.com. I also see that many are either not finding the forum and/or asking their questions…

So again I would like to offer the suggestion that you “Check It Out”

Please don’t be afraid to ask anything you would search for answers for in any search engine…In my experience there are Not a lot of sites (if any) offering personal answers out there for the Marine A/C & Refrigeration field, and it’s one of the main reasons I have offered this forum section.

Join in with questions and comments…Hopefully together we can make this a one stop source for your marine a/c info,  experiences & troubleshooting.

I personally look forward to interacting with everyone…

Note: If you do decide to register & participate…Please input your location in the space provided as it helps to know your climate without having to ask.

Steve~