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Old 06-07-2012, 06:41   #1
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a few cruiseair AC questions

a few cruiseair AC questions for an older system with rotary knobs

I recently fixed my cruiseair 16,000 btu AC dual split system
I recharged with HC22A and low is 70 to 75 and high 225 when it is 95 degrees outside.
I must put the rubber insulating cover on the suction lines. This will make it more efficient and it also aids in cooling the compressor.

It is back where originally installed sitting about 2 feet away from a HOT generator.
It cooled the boat well, especially at night. We took boat out for the fourth and it was 100 degrees outside.

A couple times the cruiseair compressor shut off, after the first time I opened the generator hatch cover to get more cooling for the area as I was worried about it overheating. Other time was returned to slip and gen set bogged down when microwave turned on and the cruisair shut off.
Otherwise the cruisair ran fine on constantly for 24 hours.

Is the location acceptable for the condensing unit
or can this cause the compressor to overheat?
If the compressor overheats does it have an overheat thermal shut off?


It does have a high pressure cut off.

I have read that the seawater must flow about 5 gallons per minute and the tube cleaned with muriatic acid this cools the compressed gas. I noticed the discharge water felt warm.
The compressor is cooled by returned gas and ambient air which is why you should cover tubes with insulation. Should both suction and discharge tubes be covered with foam insulation?

I am worried about the gen heat soaking the compressor.
If I made a thick foam barrier pink or blue like 3 inch thick to shield the condensing unit from gen heat would this be worth doing?
It would run from front to rear and mostly block the gen heat. Imagine a gen set and condensing unit sitting side by side in an enclosed space.
What about an air blower in the lazarette?
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Old 06-07-2012, 11:23   #2
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Hello there friend,
I've worked with industrial/commercial refrigeration systems and domestic AC units on occasion but never with marine units so I'm not familiar with the actual equipment your using. Theoretically they're all the same. I might be able to help.
We may need some more specific details, but these are my initial thoughts;
Insulating the return line to the compressor will indeed help with internal compressor cooling. Insulating the discharge from the compressor to the condenser unit may even make the situation worse. If the compressor is tripping an internal thermal over load switch there could be a number of reasons why, most likely the compressor is being overloaded i.e working harder than its design to:
Dirty / inefficient heat exchanger (water cooled condenser?)
Pinched refrigerant lines
Alternatively it could be a lack of oil inside the compressor (sometimes the oil is pumped out and restricted from returning).

I would be surprised if the ambient temperature around the compressor, determined by the operating genset would be a problem. The internal working temperature of the compressor is relatively high anyway.

Check the lines are ok, not pinched/bent
If you can, clean the heat exchanger sea water pipes and make sure that there's no scale/salt build up on the inside.
If the condenser is exclusively water cooled it might help to insulate it from the ambient temperature created by the genset.

What type of refrigerant throttle does the system have? Is it a thermostatic expansion valve / capillary tube or otherwise? And at which point in the system is it located? I imagine


Cheers....
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Old 06-07-2012, 16:53   #3
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Re: a few cruiseair AC questions

I think it uses a capillary tube.

How hot should the compressor get when operating normally? And if it is already in 140 degree air, then too hot to touch?

I added about 6 ozs of oil because the copper suction line cracked where it enters the condensing unit valve. I watched it happen and estimated a certain amount of oil came out. I added it by sucking it into the suction side of the unit drawing a vacuum on the discharge line. The compressor was replaced in 1993 by a prior owner. I noticed in the coil line on top an additional filter drier was fitted. (looks like a cigar)

I have read that these can be operating in ambient air to 140F

Quote:
Pumps & High Pressure…With Manual Controls & Hi Pressure Switch | marine-ac.com

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…
What I was wondering is there an external overload mounted on the compressor? Parts list suggests one. And then it could be tripping because it is old. I have not removed the clip and cover on the compressor side to have a look. I have read compressors have an internal overheat switch. So is the external one just for current overloads? If it has one, does anyone have a source to buy this?
http://www.mabrumarine.com/marine_ai...sor_overloads/
lists overloads

It is a type f condensing unit. They are affected by moisture as in rust.

http://www.boatelectric.com/L-0200-F.pdf
Quote:
The unit is not affected by moisture, vibration or ambient
temperatures up to 140F (60C). No ventilation is needed
and all components are ignition protected.
just more info
Quote:
http://forums.sbo.sailboatowners.com...ad.php?t=41425
Usually in any of these A/C systems the high pressure switch will shut down the system before the overload will. It's designed to cut out between 400-425 psi and cut back in at 250 psi. The overload cuts out on temperature at the eqivalent of the noted pressure. A set of pressure gauges and an amp meter should be used to check pressure and amps when the compressor goes off. This will help you diagnose what the possibilities are. Here's what needs to be checked:1. Pump: Even though the pump is running, that doesn't mean it's pumping to capacity. You need 3 gpm per ton of A/C so you should have at least 4.5 gpm @ 10 feet of head (vertical rise of hose taking into account any elbows used). The impeller should also be checked for wear.2. Condenser coil: Acid wash the coil using a 5% muratic acid solution in a closed loop until the water flows clear. Be careful and dispose of carefully. Also make sure all hoses are free of sea growth.3. Compressor: If the amps are high but the pressures are normal, the compressor motor might be going bad. Ohm out the compressor. Measure from common to start, common to run, start to run. Add the first two readings they should be within one ohm of the third reading. Also make sure that the run capacitor is good. A bad run capacitor can make the compressor overheat. Low Pressure: If the pressures are low there won't be enough cooling gas coming back into the suction port to cool off the compressor. It won't go off on low pressure if there's no low pressure switch installed.Hope this information helps,Barry

http://www.samsmarine.com/forums/sho...or-not-running
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Old 07-07-2012, 02:35   #4
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You've got a lot of information the to help you!

What's the compressor running current at midday? What the surface sea temperature at that time?
Underneath the plastic cap and clip there may be a bi-metal external thermal overload. I've very rarely had any problems with these unless the wire terminals are burnt due to excessive current. If I'm not mistaken they have a trip rating above 80oC. Too hot to touch a working compressor in that state!
Check the resistance between the three compressor terminals as was suggested.
It's common practice to change/install an in-line filter/dryer when you put a new compressor. You might consider to replace that now since you mentioned that you have subsequently repaired a cracked line. Make sure that you do a very good vacuum on the whole system before you recharge.
Are you still using R22? If you can't measure the refrigerant by weight when recharging (according to manufacturers specs), then aim for an evaporator pressure (return) of around 62psi (I don't have the refrigerant charts on hand but if memory serves... 75psi seems a bit high)
Again, the efficient heat exchange properties of the condenser unit is most critical. Be sure it's clean inside and the coolant sea water is flowing properly. Ie. 20l/h
One more thing, the reversing valve... I think you said 75psi low / 225psi high. I'm not certain but the one seems high and the other low to me. I've had situations when the RV valve didn't completely isolate the high side from the low side. In other words it leaked from one side to the other. If you don't run the heating cycle very often it might be an idea to energize the RV solenoid on-off a few times in the hope of it finding a better seated position.
In conclusion I think it's unlikely that your problem is the ambient temperature around the compressor. More likely there is a system fault that is making the compressor work harder than it normally should.

Check again for pinched/bent/restricted refrigerant lines. A poorly welded union with excess flux on the inside will restrict the flow of refrigerant causing a pressure drop in turn forcing the compressor to work harder...!
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Old 07-07-2012, 10:53   #5
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Re: a few cruiseair AC questions

I have read the reversing valves can get stuck and very light tapping on the very end helps to move them. Dont tap middle, might deform valve body.
When had unit out at home, I activated valve and heard loud click but found reversing valve was stuck in heat mode and did not switch to cool mode till I tapped on it. Then it was sucking on suction and pumping on discharge very well. When valve is energized = heat mode, non energized = cool mode.
Newer boat heat pumps exercise the valve when unit is turned on.

I would think you should not activate or deactivate this valve if the refrigerant is flowing. Would it not suddenly reverse the flow and cause a refrigerant pressure wave of some kind?
So how could you design a circuit to move the valve so it wont get stuck.
I would think before compressor starts send current to the valve, then do whatever is appropriate for heat or cool. Then start compressor. How could that be done?

Think on that cause you might suggest turn thermostat to high heat but even if that works you wont remember to do it so needs to be automatic done for you. I also noticed it is too hot in the cabin for the thermostat to call for heat mode.

Went to boat this AM, we are having a heat wave and outside is 100 today for Americans, 50 for Europeans.
Water temp is about 80 to 82

I checked pump flow with a 5 gallon bucket and got 5 gallons in 50 seconds so that is good. My pump is a 12 volt centrifugal bait well Attwood pump I power off a 120 volt relay in a metal box next to the condensing unit. This pump works very well and not too expensive. Outlet uses a 3/4 inch hose. IF you snug the 3/4 hose all the way up the condensing unit pipe it fits well with a clamp.

I will get some muriatic acid and clean inside of condenser. People say use 5% and recirculate over and over. However not sure how to do that with a below water line centrifugal pump? I could though take lines off pump and outlet and hold them up use a funnel to fill coils with 10% muriatic and let that sit, flush and repeat.

Started up AC unit and it was cooling. I need to check all the refrigerant lines and coat them with PL Premium polyurethane since they have some outward corrosion where they run through the lower bilge area. Then put on an insulating cover. Since it is both heat and cool, both lines should be covered and some are but over the last 40 years insulation has disappeared on much of the copper lines. I never use heat mode so I might not bother to cover the discharge lines.
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Old 07-07-2012, 10:56   #6
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Re: a few cruiseair AC questions

here is a picture of the unit.


here it is all rusty before I repaired the rust.
I turned it upside down, removed base plate, removed compressor support plate.
Scraped off all the rust.
Coated all the metal with PL premium polyurethane.
painted it.
The compressor bottom was very rusty, so also used some fiberglass tape with the PL on its bottom which gives it some strength and thickness. PL is 100% waterproof. Tip is to clean off hands or what ever you get it on you dont want it on with 91% rubbing alcohol.



The tall huge capacitor is the run cap. I have never seen one that big before.
Any ideas on these caps? Still good or not?
The short round one is the start cap.

there are 3 cans on the lines, do you know what they are called and do?
I think the top can is an add on filter-drier.
Is the left one a filter drier accumulator?

The one on the right is bolted to the bottom plate and is large round fat.
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Old 07-07-2012, 12:32   #7
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Do you have any more pictures? I'm fascinated by this now. It's not what I expected to see.
The 'cans' on top and on the left are likely to be filter/strainers. I would be surprised if they are filter/driers. On the right you have what appears to be a liquid line accumulator that feeds the evaporator.
I've never seen such a large running capacitor myself either. If you have access to a capacitance meter that'll give you an idea of where you stand (+\- 10% of rating is normally fine)
If your not going to use the unit in heating mode you might consider to remove the RV altogether, one less headache to consider.
Again, more pictures would be great, if not only for my own curiosity.
An American once told me of this great acronym he uses - KISS - I'm sure you know it yourself. It works for me 99% of the time also.
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Old 07-07-2012, 13:04   #8
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Re: a few cruiseair AC questions

I can take some more and post of the installed location in a few days.

Filter strainers? Good enough to catch debris and protect the compressor?

So there is no driers you think?
When I vac it down, I let it vac for 5 hours in the heat of a 100 degree outside day. Then let it sit overnight and vacuum stayed at 29.

Showing the discharge stem valve. A removable cap covers a valve. When the valve is all the way CCW the charge port is shut. So turn one turn CW to open charge port. The brass covered port has a shrader valve, I suppose to check pressure without opening the other valve.



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Old 07-07-2012, 13:52   #9
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That's a good vacuum technique you've got there!
The second valve may be a port for a high pressure switch or other peripheral component, I'm not sure.
Sounds like your have extraordinary weather at the moment. What would the normal range be at this time of the year?
I look forward to seeing the pictures of the unit in situ. I have some new thoughts but I'll hold on to them until we see the whole picture.
Much respect to you for sticking with this 40 year old unit. And of course, there's no reason you shouldn't. Many's a man in today's throwaway/consumer driven society would have gone with the 'upgrade' and discard option. Kudos to you my friend, whatever your motivation may be.
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Old 07-07-2012, 15:12   #10
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Re: a few cruiseair AC questions

normal high temp is mid to upper 80's this time of year.
Much of the USA is caught in a massive heat wave right now. They expect it to break early next week.
Weather Forecast Hampton, VA | Hampton Weather | Wunderground

Heat wave!

Actually my motivation is to do things myself and keep the old stuff working as long as possible. Price of this is around $2000 new. I do tend to like repairing the old and learn a lot as I go. I tend towards practical over appearance although prefer both.
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Old 11-07-2012, 21:16   #11
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Re: a few cruiseair AC questions

Ok, a few more photos

the relay box. This takes 120 volt Ac and switches 12 volt DC to run the sea water pump.


the pump I use is a 12 volt DC cheap centrifugal bait pump. It pumps over 5 gallons per minute which I verified. This Attwood pump is a 750gph and runs so quiet you can not hear it running.



the condensing unit fitted with 3/4 inch hose. They snug up tight when pushed this far up the tubing. I have double insulated the suction tubing, insulation on top of insulation every where. So two layers thick.


showing the tight fit of gen and cruisair.


showing my insulating piece of polyiso foam 2 inches thick foil faced. I tested when running and you can feel gen heat on gen side, other side stays cool. Bought this board at HD. Used aluminum duct tape to join the layers together.



main cooler in salon. Has the 3 knob rotary control and a loud fan.
Is there a way to make this fan quiet like the other fan?


slave unit in lower cabin. Very quiet fan.


showing backside of slave unit


Here i am covering the copper tubes in lower bilge.
These lines run to the lower cabin slave cooler evaporator.
These were installed in 1971 and had some corrosion on the copper. I cleaned this off. I am wrapping fiberglass wall board tape around the tubing. This has a sticky side so stays in place. Then I coat with PL premium polyurethane to seal. The tape bulks up the glue. This will be 100% waterproof and still quite flexible unlike If I had used epoxy.

Suction line is 3/8. Discharge line is 1/4.
Condensing unit is 16000 btu which calls for a 1/2 suction line. But the original install used 3/8?? Who knows what they did. I had to solder a piece of 1/2 to 3/8 when attaching the flare to the condensor. Some ape had managed to create a huge flare for the 3/8 tube which after a few decades cracked on me.

I figure realy it should be 1/2 inch suction at least to the first 'tee' where it divides to both coolers. Is there any penalty to using this 3/8 line??
I figure 3/8 after the 'tee' off split is ok.



hard to see but the glue is smeared on. I put tape on, smeared on glue, then did another layer and smeared on more glue.
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