Hi Jay~

Glad you got back in…Sorry for the deletion…

With the temps you give I'm thinking pressures might be around 65-67 suction & 215-230 head with a clean condenser coil & full water flow…But since you bought the unit used & it may have a scaled up condenser coil they both could be higher than that…Head will affect suction some….And the size duct you installed can affect this too…But your brother likely already knows this…

To be sure someone did not put the wrong gas in (or mix it)…And since you do have a brother that is a tech and likely to have the equipment…I'd evacuate the unit, and go with a fresh charge of virgin R-22…

Again if he wants to weigh in the charge with a scale…That spec should be on the unit's data plate.

The main thing that you are looking for is a cold suction line back to the compressor (this cools the compressor) without the compressor itself getting cold…Most residential HVAC techs don't have this luxury of feeling the suction line at the compressor while charging because they usually can't get past the running condenser fan to reach it…But tell him while charging…Constantly hold the suction line…When he feels it change from cool to cold…Stop charging…

Also he can charge by Superheat…Were looking for around 12-15 degrees…Cold cabin as much as 20 but no more…

If he can't get a cold suction at those pressures I mentioned above (or without the head climbing way high) then I would say that the condenser coil is scaled up (hard water scale) & will need to be acid washed…

Let me know how it goes…

Steve~

32avanti said:

Jay~

I'm thinking your "VRE" 16K unit, because of it's age (90-91) is a piston type compressor unit, as opposed to a rotary compressor…Rotary's run Hot…Piston's should Not…I need to confirm which type your unit has…If it is a piston type the model # on the top of the compressor should read AK 8515E…

Steve,

 

 My brother and  I spent a few hours on this yesterday….. upon initial hook up of the gauges the pressures seemed close to what you suggested but a bit high,my brother insisted on a complete reclaim,evacuation and weigh in of proper amount of refrigerant (17oz)so he had a fresh start to base things off of. After performing the above mentioned the pressures seemed to right on the money with your suggestions but the unit still is affected with the same condition no restart after temp is satisfied. pops main breaker on boat.…This is all good…Except the breaker tripping…I don't feel we have a reversing valve problem with those pressures…More on the breaker in a minute…

 

My brother asked me to report to you the following,after recharge we have suction psi of 65 head psi 220 cooling properly with a cool suction line,pumping solid stream of water overbaord,compressor and suction line extremely hot.…This statement is confusing Jay…Which is it ?…First you say Cool suction Line…Then you say Extremely Hot…The refrigerant suction line where it enters the compressor should be "Beer Can Cold"

 

Once temp is satisfied and unit calls for cooling again the compressor becomes loud and slugs, pops breaker.

How do we know it slugs ?

 

Once unit cools it will start back up and properlly cool.

 

Some of the "old timers" on his crew are suggesting lack of cooling to the compressor and saying if reversing valve was bad it would not cool that good?  I there some type of seperate "loop" or "Coil" thes sends water to cool the compressor that could possibly be clogged?…Dang those "Old Timers"…They are right almost every time !!!   …

But not quite this time…Yes overheating will cause a compressor to seize, but in this case the only cooling of the compressor is done by returning refrigerant (the seawater only takes the heat out of the refrigerant) that's why charge level is so critical…Home units have the condenser fan to help by drawing air across the compressor.

 

But we are not familiar with how it works and i dont want too many hands in the pot.

 

So brother and I will wait for your opinion.

 

Here is where we get back to the breaker thing…What breaker ?…Main shore or the A/C breaker ?…What amperage is that breaker ?

What kind of shorepower do you have ?…Are you in a Marina with 30 amp service, or is this behind a house with 15-20 amp service adapted to the boat ?

What is the incoming voltage, and do you notice it drop as the unit runs ???…Low voltage can cause overheated compressors too…

What could be happening is the shore wire was not sized for A/C load, and is overheating as the unit runs, thus dropping voltage…Then when the unit cycles it's not off long enough for those wire/connections to cool enough to supply the voltage/amperage needed for a re-start…50 amps or more (LRA on that compressor is 74) and Marine Air did not use a Start Relay & Capacitor to help either….

I'm assuming your brother has verified with his gauges that the system pressures are equalized before the unit tries to re-start ???…I'm sure he would have mentioned if not…

We can add a All in One Start Assist Kit (good) or a Dometic SmartStart (best) but First & Foremost you need to be sure about your shore power….Compressors hate low voltage, but if you have overheating wires & connections you could have a fire when they finally give out… 

An easy way to verify this is if you have a generator installed…Run the unit on generator & if it cycles ok that way…You know it's a shore power problem…Otherwise break out the meters & check for hot wires & connections….

 

S

 

Thanks again Steve!

 

Jay

Post edited 9:20 pm – June 7, 2011 by 32avanti

^Stupid Smart Phone^

Steve, I miss spoke suction line ice cold,liquid line and compressor very hot.

Boat is on dedicated 30a single circuit in a marina, The unit is popping the main shore power breaker on main panel inside boat the boat was pre wired for  electric heat from the Factory we used the 30a breaker in ac panel for the air install ,needle on panel indicates 115-120? Does not move at all when unit kicks on…….my bother mentioned that the compressor acts like its "slugging" that's all?? im kind of out of my realm here with terminoligy.

Unit is  powered on  a sepaerate  30a dedicated breaker in main panel.

I will be at boat after work on Wed and try to get model # of compressor and take some readings if I can find a buddy with a meter stay tuned and thanks again.

I guess its time to look at wiring, guess I will start on dock and work my way inward?

Funny thing I want to mention Boat across dock is same model and make and year we mimicked his ac install and did everything the same and of course his is fine 1st thing im doing is plugging into his shore power outlet.

I have been in the same slip for 11years and never tripped a breaker though?

Steve,

 Made it ti the boat last night alone checked Model # it is the VRE 16K.

 It was in the upper 90's today so I grabbed the meter and started at the unit with it running and cooling I checked the voltage on the power incoming into the large white control box I have a solid 117-119v with the unit running under a full load and within 2-3 minutes a VERY hot compressor. The wires from the breaker panel to the unit are room temp.

 We then tried the shore power in the boat across the docks recepticale and let the unit cool down and rechecked with the same results,so unless there is a wiring problem between the control panel and the compressor I think the electrical power supply is ok?

What would I check from the control box to the compressor except for loose or corroded wiring,wich I plan on doing over the weekend.

Just as a side note mounted on the side of the white "control box" i discovered a "kick Start" capacitor im assuming this is for the compressor?

You mentioned the run capacitor is that under the grey plastic cap on top of the compressor,if so it appears to look fine?

I guess at this point we need to figure out what would cause the compressor to get so hot so fast this is obviosly why it wont restart until cool,if there was a pro in the area I would have called them in but we have nobody that I know of.

Any other thoughts are welcome as my brother who is way more mechanically inclined than me will be up at lake for the weekend and this is driving him nuts so I know he will be all over it.

Thanks!