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~

Unit model VRE16K-H (Rotary Compressor) 16,000 BTU 115 volt.

This unit new with control & cable would retail for over $3000.

$700.00 + Shipping…Price reduced for quick sale…$600 + Shipping

This system is priced lower than a digital control retrofit kit from Marine Air…It’s like you’re getting a 16K  A/C unit in good shape for nothing…

If local can demo on bench.

Join the forum discussion on this post

Recently I was on a boating message board and came across a discussion about pumps and some troubles folks had experienced.

The original poster had a March magnetic drive pump that would not pump water, and after the usual back flush & priming sugguestions he could still not get it to pump water…Just before I read the thread he had found that either something had gotten past the strainer (or he didn’t have one) and had lodged between the impeller magnet and the pump housing stopping the impeller from turning, but not the motor from running…

Then the questions & discussion centered around how their systems reacted to loss of water flow and how & when their pump ran…Some of it was info that was a bit misleading for others depending on what type of system & control they have…So I posted these two posts below to try to help out…It’s good info so why not share it here on my own site too ?

• My first post…

I’m glad the Chief Alen sorted out his pump problem but I thought I could add a bit of info to the thread…

If it is a single A/C system installed (not more than one compressor or control) there will be no need for a pump relay.

If it is a older Cruisair 3 knob type cabin control…Yes the pump will run with the fan and not cycle with the compressor unless it has been changed or is a newer digital control.

The thought back in those days was that when wired to the fan circuit…The owner could verify flow over the side before switching the system to run…They have since re-thought, and have changed that practice/wiring…

Yes it can also be wired to the compressor circuit so that it will cycle with the compressor…
It can be a simple change, but first you need to find where the pump wire runs to…Some run to the unit, and others are run to the terminal strip that should be within 3 feet of the cabin control….You then just remove the black pump wire from under the red terminal (Cruisair) and reconnect it along with the purple compressor wire…The pump should then cycle with the t-stat/compressor.

The other thing to watch for with the March Mag drive pumps is if they are run dry for very long…They will heat up enough to melt the plastic on the back side of the impeller around the ceramic shaft, and also the impeller mating surface of the plastic head itself…
The impeller may appear to rotate fine when the cover is removed but it won’t when the pressure of the cover is against the impeller with the cover installed…If this is the case…The housing & impeller can be replaced, or you can also get the complete head without having to replace the whole pump.

Steve~

• Then another gentleman posted…

“I guess I must have the ideal system. If the water flow is disrupted on mine…the breaker trips.”

• My reply…

That is a good thing…But not actually a function of design of the A/C system or control.

I’ll try to explain…

Most Marine A/C units with manual cabin controls have what is called a “Line Voltage” automatic reset high pressure switch (meaning it is actually carrying the compressor current) that trips around 425 psi, but then resets itself at around 325 psi…

Mermaid was one exception…They had/have a Manual reset Hi PS Switch with a push to reset button…Anyway…

Normal system operating high side pressure is somewhere between 200-250 psi depending on water flow & the temp of that seawater…

Also…In a Normal startup (system has been idle for a few minutes) the low & high side pressures will be equal (or very close)
This pressure will depend on ambient air temp but it will not ever be much over 196 psi (that’s assuming a 100 degree cabin)and usually much lower.

The compressor has a fairly easy time getting rolling against that kind of pressure….But at where the pressure switch resets (325 psi) it has a much tougher time and thus draws much more amperage (than normal) in trying to re-start against that High pressure…Therefore tripping the breaker…

Units that didn’t come with a start relay & capacitor have a harder time starting than ones that did come so equipped…

The ones that came equipped usually will start on lower dock power, and also may re-start at that 325 psi if the breaker is not closely matched to the size system it is powering…

Breakers are most often spec’d for wire size & distance to any given piece of equipment (under normal load conditions) for that equipment…The wire is also sized to be able to carry that projected load.

So you might see…There are trade offs…

Tripping that breaker weakens it a bit every time…Yeah I know…It shouldn’t happen that often…And it does protect my A/C & Pump…

But having a unit that did not come with start components can mean the difference of being cool, or not being cool with marginal dock power (Like at a lot of backwoods marinas, and behind many homes) It can also mean a given unit may or may not start on a smaller gen set or inverter with other essentials running…

Tanqueray…I’m not saying your unit does or does not have start components…I’d have to know what you have to know that, but I can also say to everyone that a start kit can be added very easily to most all systems that don’t have a relay & capacitor already installed if your situation warrants it…

The reason most manufacturers didn’t use them was cost…I can also add that up until a few years ago Cruisair had them on all their units.

Note: The digital controls of Cruisair/Marine Air handle Hi/Ps much differently than manual controls….But that’s another post…

Steve~

Join the forum discussion on this post

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~

They do provide the same function as in home systems as they are designed to keep the temperature in the cabin/room at a selected temp within a few degrees…

But different than Home…They can (and most do nowadays) offer more/different features than we use at home depending on the type of marine control that is installed…We can cover some of those features here but first we need to define which type of control is installed…Although there have been and are many types and models of controls with several variations…

Lets first describe the most popular two main types…

Manual Controls…

The old standby that has been around for many years is the three knob manual control (non digital) it has/had 3 control knobs each with a different function & was/is available in either a vertical or horizontal, rectangular form factor…

The typical function of each knob was as follows…

• The first knob was a function knob with Off, Start (sometimes labeled Fan) and Run positions…

The functions of each position were pretty much self explanatory except that the Start/Fan position ran the fan but also started the seawater pump so that you could look over the side of the boat to verify it was pumping water before selecting Run.

The Run position sent power thru the thermostat which then would decide whether to start the compressor in the cool, or heat mode depending on cabin temp, and the position of the thermostat knob…(more on that in a minute)

• The second knob was a Variable Fan Speed control (not usually available at home)

It was useful at night for lowering blower noise to watch TV etc…(how low was low was adjustable but the control needed to be removed to adjust this parameter with a small screwdriver)

• The third knob was the thermostat…

This was the most misunderstood function of this control because it had no temp numbers (It was also the hardest to explain to folks)  Most would just crank it to it’s coldest setting thinking that the further they turned it…The colder the air would come out…That’s true in a way, but it’s not a function of the control, and A/C does not work that way…I will try to explain…

Regardless of control setting or type…All R-22 A/C systems work on a 15 to 18 degree temp exchange design…Meaning that the air coming out of the discharge grill should be 15 to 18 degrees colder than what is going into the return air grill (if it’s more, or less than that, there is likely a problem with the system or installation)

So if it’s 90 degrees in the space being cooled…don’t expect much colder than 75-72 degree air coming out the discharge with any R-22 A/C system…But as the room/cabin cools, that exchange is maintained, and the air continues to come out colder by 15 to 18 degrees of what goes in….Lower room temp=lower discharge air temp.

The thermostat tells the compressor when to run or not run, and energizes the reversing valve when reverse cycle heat is needed to maintain cabin temp of the setting on the dial (position of the arrow)…Generally speaking…A properly calibrated t-stat set with the arrow pointed vertical should maintain around 70-74 degrees cabin temp…Anything to the right is a colder cabin, and to the left of vertical is warmer…The T-Stat will allow the compressor to run until the cabin gets to the selected temp (on the knob) at which point it cuts power to the compressor until the cabin either warms or cools a few degrees, at which point it then again sends power back to the compressor/reversing valve as needed to bring the cabin back to selected temp.

These controls offered very little in system protection and thus it was not advisable to run the A/C system unattended for very long.

Digital Controls…

Started hitting the market in the mid 80’s…They at first like any new product, had a few weaknesses and thus some early problems, but as they matured they have now become the standard, and are very reliable…

 They also allow the marine A/C manufacturers to offer extended warranty periods when installed with new equipment because of the system fault protection/shutdown features they provide, along with the many other benefits/features…I can’t count the compressors & pumps they have saved for my customers…Many of them don’t realize it either, but they do help immensely…

The features & protections offered by these newer microprocessor based cabin/system controls are likely too many to mention here but I will list some of the more important below…

Protection:

• High Pressure Shutdown…Loss of Seawater flow…This can save a compressor and or seawater pump failure, from running without water. (Did you check that strainer & thru hull ?)
• Low Pressure Shutdown…Loss of Freon or a dirty air filter…Can also save a compressor….
• Low AC power Shutdown…One of the worst things for a compressor is low voltage.
• Seawater Pump shuts off with compressor (on single system boats) so that pump can be saved from no water burnout of pump head (this will also protect pump if only one system is run while away on multi system boats)
• Programmable Time Delays…So that multiple systems don’t all start at once when shifting from Shore to Gen or vise verse causing tripped breakers and/or heavy surges.

Features:

• Digital Display of Setpoint (Temp you want the cabin to be) & Actual Temp of that cabin.
• Much more accurate temp control. (when compared to the 3 knob control or others)
• Automatic Fan Speed control…Fan speed can be controlled by how far away you are from setpoint…Manual speed is also an option so that if you don’t want it to change it won’t.
• Ability to program Continuous or Intermittent Fan (Like the Auto fan feature at home)
• Humidity Control program…System can be activated to remove humidity only while away..This greatly reduces run time while keeping mold out (you probably won’t find this feature in most home controls)
• Some have IR remote control availability/operation.
• Some have networking ability…So that they can all be linked and controlled from a central (keypad) location, or from any individual control location aboard.

These are some of the most important features, but the controls are fully programmable for many more user adjustable functions (depending on model)

If you have one or more of these digital controls…The not so funny thing I find here in West Central Fl…Is that about 95% of the boats I go on have never had the digital controls setup for the boat/installation…

The A/C manufacturer has a set of Default settings they ship the controls programmed with…These are just that…Defaults that the manufacturer feels that all systems should operate safely with once installed…It’s generally thought that it’s the installers responsibility to perform the calibration…Unfortunately it’s likely that the boat builder or original installer did not do this for many reasons…One of which might be they don’t know about them ?…

Anyway as I said…Most of the boats I go on still have the factory defaults set in the controls, and a lot of these boats are many years old…They are by no means the best settings for each installation or system, and again if you have these controls, you may find that you will enjoy your system/s much more if you get your trusty A/C guy out to to go thru them…Or get the manual out yourself to take a look….

Many also ask if the newer digital controls can be retrofit to take the place of others…Yes they can…I have installed them on just about every application of marine A/C made in the last 40 years…Yeah…That’s longer than I have been working on marine A/C but I do/have seen some old stuff still in operation…and Usually after we install one on a boat and calibrate it…The owner almost always wants another…

If you are having troubles with either type control…We can help with troubleshooting in the Forum section…Just post your type control and problem and I will do my best to walk you thru it to an answer…

Steve~