SailNet Community banner

1 - 18 of 18 Posts

·
Registered
Joined
·
355 Posts
Discussion Starter · #1 ·
Can an auto parts store AC kit be used to add refrigerant to a 12500 btu Cruisair AC unit? I'd like to do it myself, if possible.
Thanks, Marc
 

·
Registered
Joined
·
5,067 Posts
An autoparts store AC kit will or 'may' be sufficient to do the job you require. Id opt for those 134a kits that indicate and 'correlate' ambient temperature for the correct pressure (vs. ambient temperature) delivery. Such is indicated on the gage (pressure vs. ambient temperature) of the 134a charging kit/unit.

That stated, you will not be removing any air or excess moisture in the refrigerant lines, etc. of the unit, as that needs a vacuum process to eliminate such contamination that can/will cause inefficiency of cooling. So, if your DIY 'refill' does not work out for you, then consider to have a refrig. tech do a 'complete' refill job for you. Best course is always 'do it the right way the first time'.
 

·
Old enough to know better
Joined
·
4,346 Posts
Also depends on the refrigerant it has now if R12 you will want to convert the system first replacing seals and the old oil. I have used the "kit”,on an old car that it would have cost more to do it right than the car was worth and it worked for a year without issue. But if you want it to last do it right.
 

·
Registered
Joined
·
1,547 Posts
IF you know what refridgerant it takes, and how much and where to insert the "can" and whether to hold it upside down or not....you might make it better. Might make it worse.

What is it doing that you feel it needs a recharge?

For the cost of a service call, I would have a marine air tech come out and do it right, the first time.
 

·
One of None
Joined
·
8,040 Posts
Marc, I'm saying this as kindly as possibly if you have to ask please, don't even try. It may be a 410A unit. although 134A is most likely.

Marine AC units, are like home refrigeration and window ACs, they are factory built under controlled conditions and very unlikely to ever need "a shot"

As they age, electrolysis, rough, handling,cleaning with sharp objects may cause it to loose refrigerant but it's more likely to not work at all or freeze up. Low water flow, blocked air filter, clogged heat EX, water not pumping, closed or forgot to open the water valve/s all can cause problems making the lay person think it needs a shot of gas ;)

Please try to describe what is happening, not happening, age, model number, pump, strainer, locations, . Heat exchangers on AC units need cleaning. White vinegar is one of the best "acids" to use.

Hope this helps!
 

·
Master Mariner
Joined
·
9,055 Posts
You might be better served by hiring a professional because you need to find the leak. Refrigerant does not just up and disappear, nor does it get used up. If you need a recharge, then you have a leak. If you have water or air in the system, then you could be putting a $2000.00 unit at risk for the price of a service call.
 

·
Registered
Joined
·
3,157 Posts
Yeah it's not really a DIY job, because it is not just a case of "topping up" a system. It needs a specific amount of refrigerant in order to work correctly. Too much or too little and the system will not work properly, and could easily be damaged.

You really need to have the right tools and the right knowledge to fix refrigeration systems.
 

·
Registered
Joined
·
22 Posts
I am a professional hvac tech.if you need refrigerant then there is a leak. First make sure the coils are clean if they sre not ckean you will not get true pressure tempitures. Dirty coils will cause a lot of problems. Use good gages the cheap gauges are not very accurate. Check for leajs if it is low on freon. Common easy to fix leaks are Shrader valves but the tool is 49 dollars. A cheap one wull work.. if it is low use soapy water wher there are welds it will make bubbles where the leak is. The new refrigerants are a much higher pressure than r22 or r12. Going to 134a you will not be happy. Imho if it is more than cleaning coils replace it. Why you ask. The old refrigerants are getting expencive. A newer system will be more efficient. Make sure the fan blades are clean.
 

·
Registered
Joined
·
355 Posts
Discussion Starter · #9 ·
Thanks everyone. It seems this is not a DIY project. I guess I'll have to get a Pro to look at it.
Thanks, Marc
 

·
One of None
Joined
·
8,040 Posts
Marc we could run you through the basics like making sure you have the right water flow, pump working, etc.. what caused you think it may need refrigerant?
 

·
Registered
Joined
·
4,985 Posts
A quick look online shows the current Cruisair units use R-410a, not R-134a. Putting the R-134a you get from the auto parts store into a unit using R-410a would be a disaster. Would require complete recovery and proper disposal of the mixed charge, followed by evacuation and then proper recharging.
 

·
Registered
Joined
·
3,157 Posts
If it is old, it likely isn't 410a, but if it is it should be well marked.

I agree, we may be able to help you save a service call, or at least have an idea what is wrong when you call him.

Is the compressor definitely running and it doesn't cool? Does it stop and start a lot? Can you measure the air temps?
 

·
Registered
Joined
·
845 Posts
I would recommend a service call from a pro. Like previous posted shrader vales have a tendency to leak. A pro with a "sniffer" will find the leak pretty quick. Keep in mind that it should be a quiet day or on the hard so the scale will work right if the tech is weighing refrigerent as he is putting it in.

Good advice
I am a professional hvac tech.if you need refrigerant then there is a leak. First make sure the coils are clean if they sre not ckean you will not get true pressure tempitures. Dirty coils will cause a lot of problems. Use good gages the cheap gauges are not very accurate. Check for leajs if it is low on freon. Common easy to fix leaks are Shrader valves but the tool is 49 dollars. A cheap one wull work.. if it is low use soapy water wher there are welds it will make bubbles where the leak is. The new refrigerants are a much higher pressure than r22 or r12. Going to 134a you will not be happy. Imho if it is more than cleaning coils replace it. Why you ask. The old refrigerants are getting expencive. A newer system will be more efficient. Make sure the fan blades are clean.
 

·
One of None
Joined
·
8,040 Posts
OMG I remember a gadget called a halide sniffer. it used a torch and a tube to the flame and if there was CFCs in the air being drawn up the tube by the flame's convection the flame would turn green.. very "hi tech" LOL NOT suggested using it in flammable environments!
 

·
Registered
Joined
·
1 Posts
I have a danfoss compressor and my boat is 200 miles from the nearest "qualified" technician.

I need to know the part number for the adapter that will convert the danfoss shrader valve to the ones that work on automobile compressors. I have the complete instructions for the danfoss and a vacuum pump and a complete set of gauges. "yes the expensive ones"

I tend to give stuff away that I can't fix, and since the people around where my boat is only know Diesel engines I just get a blank look when I mention hvac, I really could use the info.

If it is not available I'll have one made and post it. I'm sure I'm not the only one who could diagnose a leak and top off "correctly" a refrigeration circuit in an emergency.

It's not just beer people have to keep cold.

Thanks
 

·
Master Mariner
Joined
·
9,055 Posts
We were warned by a refer guy that the "auto" refrigerant has oil in it which should not be used in a marine system, as there is plenty in there already. The 134a can be had in the 12 oz bottles with or without oil (lubricant) at the same price.
Also, be sure your gauges are for 134a if that is what your system uses. It should say right on the face of the gauges. There are different manifold gauge sets for each gas.
Good luck.
 

·
One of None
Joined
·
8,040 Posts
air conditioning is more forgiving with diyers. since you mentioned a Danfoss compressor I can only assume its refrigeration, that being the case the refrigerant charge must be exact and it is usually under or around 5 ounces there is no adapter it's a simple quarter inch flare connection with Schrader insert most likely. older automotive Schrader valves were 3/16th Schrader. The new 134 Quick Connect schraders come with adapters in134 conversion kits. 410A units tend towards 3/8 flare w/Schrader insert. 3 foot refrigeration hose holds 3 ounces so you can see the problem the only and best way to recharge a small refrigeration unit is with an electronic bathroom scale that can read fractions of ozs
 

·
Registered
Joined
·
3,157 Posts
Denise is right, if it is a small refrigeration system with a Danfoss compressor it is likely a fairly "critical charge" system. Too much or too little refrigerant will drastically affect performance and reliability.

Having said that, there is no reason that someone equipped with the right tools cannot charge a system at least well enough to keep their food from spoiling until they get back to civilization. All you really need is a set of refrigeration gauges and a good thermometer.

Most small boat refrigeration systems are Capillary Tube systems. They are very sensitive to charge since, unlike TX Valve systems, they don't have the ability to modulate refrigerant flow. Here are some tips on charging a cap tube system.

The biggest concern is over-charging since that can result in liquid refrigerant flooding back to the compressor where it can damage valves. The way to ensure that you don't over charge is to do it with no load in the box, and monitor the temperature of the suction line leaving the evaporator. The Gauges likely have temperature scales for a number of different refrigerants marked on them as well as the pressure scale. If they don't have a scale for the refrigerant you are working with, you will need to download a pressure/temperature chart for your refrigerant. The temperature/pressure relationship on that scale ONLY applies when the refrigerant is in a "saturated" condition, meaning that both liquid and vapor are present at the same time. That is telling you your evaporator temperature. Then you compare that temperature to your suction line temperature, which is the temperature of the suction gas going back to the compressor. The difference between those two numbers is called Superheat. So if your gauges say 20 degrees, and your thermometer says 30deg then you have 10 degrees of superheat. If you run your empty cooler box down to it's coldest setting, and you still have 5-10 degrees of superheat then you can be pretty sure that you are not going to get liquid flood back. The closer you get to 0deg SH the greater the chance of flooding back. Once you load your box up your SH will go up as well. Some people might charge until the suction line starts to frost up since that is a sign that there is liquid refrigerant still boiling off, but it is also possible for pure suction gas to be below freezing as well, so using a good thermometer is the better way.

Of course all of this is assuming that the system does indeed just need to be charged up, and there are hazards involved. For example, if a system is really low on refrigerant the low side could easily be in a vacuum, and if you put your gauge hose onto that low side port, all of the air and moisture in the hose could be sucked into the system, and there it will cause havoc until you get the system properly vacuum pumped. If you connect your hoses with the system off, there is less chance the low side will be in a vacuum. Always bleed your hoses by cracking the gauge end so the system pressure can force the air out of your hoses.

Of course what I have described is fairly basic, but it should be enough for someone to keep their refrigeration going in a pinch.
 
1 - 18 of 18 Posts
Top