DEMETRIC AIR - Formally Marine AIRRRRRR

[Al B]

I have a 9000 BTU Marine AIRRRRRRRR now Demetric
Unit is 15 years old ,
Cabin always super cold , Other evening I woke too a pool
of my own sweat , Was 100 in cabin , Not a live a board but will sleep
aboard at times , This happened once before last season , ICE on the condenser ,
Water pumping out the side of boat ,
Closed ,
During a few days I called a number of marine a/c guys ,
Figuring it needed service , NOBODY returned calls , Typical of most marine
people working in this industry , After a few calls too the same
company , I left a annoyed message , DONT YOU RETURN CALLS
Within a few hours a return call , SORRY , was out of office ,
Telling them it unit froze a few times , They tried too walk me thru some basic stuff , filter, all clean , Possibly heat outside too low temp setting
within cabin , I did have a hat blocking thermostat , and thermostat set at
low seventies ,
I am now keeping thermostat 85 seeing what happens
GET THIS , A/C company said 6 week wait , HUH , adding insult too the situation , this company has satellite shop ( Daytona )
1/2 mile from me, next marina ,
They charge 150 service call , 125 hour plus parts , I can see this
turning out too be $ 700 bucks , I can purchase a new one $ 1500
Boat is a 2004, little by little everything is being replaced , including engines ,
Never messing with this type , is it straight forward , hook up
30 amp on my boat hooked up too generator & dockside
Biggest issue is getting it out of aft cabin ,
any thoughts

[jt11791]

Marine Airrrrr is now "Dometic".


Is yours a self contained unit with compressor and evaporator mounted together? These are fairly simple to replace. If the compressor and evaporator are mounted separately with copper lines connecting them, it's a bigger job and you may be better off going with a professional installer.

[Gary S]

Did you confirm that the unit had iced over again? It is the evaporator by the way that would be iced, not the condenser.

Typically there are two reasons why the evaporator will ice up: insufficient airflow or low refrigerant charge.

First check filter, intake grill, fan operation, ducting, and discharge grill(s) to make sure everything is sized and installed properly. I have seen blankets or bedding unknowingly blocking air intakes before, causing the unit to freeze up.

If that's all good, then you need a service tech to check your pressures/temperatures/subcooling to determine if you need more refrigerant charge.

[Al B]

Thank you for the quick response ,
Going too boat today , Will do a little poking
What iced up was the grill behind the filter ,
Can't see anything else , Have too re-move unit
Ac unit mounted in a box installed by boat mfg , In aft cabin ,
like anything else on this boat getting too everything is challenge
When it froze it had a sheet of thick ice on the grill , don't know if ice was on other areas
Later that morning , noticed a hat was hanging on a light covering thermostat , Could the blocking hat effect these type of thermostats ?
Unit is a self contained unit ,
I am in the restaurant business , refrigeration techs at my
restaurant all the time , I am considering removing , unit, taking too my
restaurant having techs check the Freon level but when I talk too them
saying its water cooled , they zone out ,
They know refrigeration but marine is a foreign too them , Don't know if it needs too be running and cooling too properly service
Might be smarter too replace , then pay high labor on a old unit
Was at boat other day , Cabin temp reading on thermostat 110
Turned on A/C and cabin within the hour cabin temp was 84. comfortable , Its a small cabin , only one vent blowing and makes cabin extremely cold , sometimes too cold needing blankets
I raised thermostat temp too 85 , see what happens

[MV Wanderlust]

Originally Posted by Gary S

Typically there are two reasons why the evaporator will ice up: insufficient airflow or low refrigerant charge.

Typically. But I have seen an exception and that could be what's happening this time. The thermistor, the little part that senses the ambient temperature, sends a signal to the circuit board to regulate the flow of refrigerant by turning off and on the compressor. If the thermistor is defective, or otherwise sensing the wrong temperature, the compressor may be continuously running until the coils freeze over.

It's possible, if the thermistor was covered, it might not be sensing the ambient temperature correctly. Possible. Maybe. It's also possible the circuit board isn't switching off the compressor like it should. Thermistors are cheap and easy to replace. A circuit board is a little more complicated to replace but would be far cheaper than a new unit. IF you could get a technician out there, they might be able to diagnose it. Big IF, it sounds like. My technician could diagnose it but he's on the west coast of Florida.

There is probably a plethora of people on this forum who have much more air conditioning knowledge and experience than I and they may poke all kinds of holes in the above info. Have at it.

John

[GordMay]

Originally Posted by Gary S

Did you confirm that the unit had iced over again? It is the evaporator by the way that would be iced, not the condenser.
Typically there are two reasons why the evaporator will ice up: insufficient airflow or low refrigerant charge...

Indeed: Evapourator cold - Condenser hot.


A window type A/C

[Gary S]

The grill behind the filter is the evaporator.

The unit will need to be run to check proper charge level and operation. It could be evacuated and recharged to factory charge level if removed, but I wouldn't recommend that.

What controller (thermostat) is installed? A hat hanging over it shouldn't matter.

[ranger58sb]

Might also be that the reversing valve... isn't. Usually that will periodically reverse the cycle from AC to heat, in order to de-ice the coils. I've read sometimes you can "encourage" a temporarily-stuck reversing valve with a light tap from a hammer or some such.

Get the manual and diagram/schematic from the Dometic website, so you can identify the reversing valve..

In that era, the likely product would have been called a Marine Airrrr Vector Compact.

The newer Vector Turbo -- now Dometic's DTU -- is better and a relatively easy drop-in, if you have to replace.

-Chris

[stormalong]

If this unit is from 2004 and has never been out it might just need a cleaning. After a while dust accumulates on the evaporator, even with a filter. Try this: Remove the filter and vacuum the evaporator. If you see dust coming off you may have solved the problem or at least identified it. To thoroughly clean it remove the unit and take it to a garage and ask the mechanic to blow out the evaporator with an air nozzle. Do it from the exhaust side towards the intake side (reverse of normal flow).

[Cadence]

Originally Posted by ranger42c

Might also be that the reversing valve... isn't. Usually that will periodically reverse the cycle from AC to heat, in order to de-ice the coils. I've read sometimes you can "encourage" a temporarily-stuck reversing valve with a light tap from a hammer or some such.

Get the manual and diagram/schematic from the Dometic website, so you can identify the reversing valve..

In that era, the likely product would have been called a Marine Airrrr Vector Compact.

The newer Vector Turbo -- now Dometic's DTU -- is better and a relatively easy drop-in, if you have to replace.

-Chris

The reversing value can be wacked to shock it loose as you said. How long it will continue to work? Worth a try.

[GordMay]

Originally Posted by stormalong

If this unit is from 2004 and has never been out it might just need a cleaning. After a while dust accumulates on the evaporator, even with a filter. Try this: Remove the filter and vacuum the evaporator. If you see dust coming off you may have solved the problem or at least identified it. To thoroughly clean it remove the unit and take it to a garage and ask the mechanic to blow out the evaporator with an air nozzle. Do it from the exhaust side towards the intake side (reverse of normal flow).

A fin comb is often used to repair bent evaporator & condenser fins to improve air flow efficiency, and also removes debris that has accumulated over time.

[Coolerking]

Make sure the fan is always running regardless of the compressor being called for, make sure the tstat will actually shut the system off when any setpoint is reached, make sure to set it to a temp it can reach so it doesn't just run for hours, make sure the ducting isn't smashed, and lastly, turn it off on the tstat, make sure it actually turns off.

Some times the boards fail and this can cause the compressor to run as soon as the breaker is powered on, regardless of whether the unit is turned on at the tstat.

[Flagship Marine]

With only one vent and that the unit got the cabin very cold was that vent closed or blocked?

[alansmith]

Not to snatch the thread....but... the Dometic DTU mentioned earlier requires a start up amperage of 36 amps. Min/max amperage of 12/14 amps... can the Honda 2000 achieve that startup if unit plugged directly into Honda?

[OS2Dude]

If it is a self contained unit (like my Webasto FCF) it is sealed and there are no ports to recharge the unit. In theory someone can braze a port in to recharge it but that would likely be difficult to do in-situ.