air con issues

[Pascal]

I'm having some issues with 2 of my ACs... Ocean Breeze 16k condensin units (about 4 years old) with 1 or 2 year old cruisair air handler.

on one of them (rear saloon), the compressor shuts down and restarts every few minutes (5 to 10) even though set temp has not been reached. the electronic control still shows the compressor is running (little dot next to temp) but checking it in the ER, i cna see it's not running. after a while, it starts again...

I'm suspecting that an overheat sensor on the compressor shuts it down. The compressor is hot when running, 150/160 deg on the top

Another one, master SR, is taking forever to cool the room.. even after 3 hours in the late afternoon, temp only gets down to 79... late into the night, it will get down to 76 but no lower than that. Water temp is starting to creep up but it's not even at its peak...

what bothers me is that the compressor runs VERY hot, as in too hot to touch... about 200+... yet no temp safety kicks in... like is suspect on the rear saloon.

water flow is good... I checked each discharge individually, plenty of water coming out. they were cleaned about 2 years ago, so they're getting there but that doesnt' explain it all since one unit is working perfectly...

i've also noticed that temp on the water / gas tubes vary... on one good running unit, i noted 130 deg on the tubes... the master SR tubes run cooler, about 100 degrees...

I dont' have a set of gauges, yet, and have lost all confidence it the guys that I've used in the past.

question... what causes a compressor to run hot ? low pressure ? high pressure ?

[fixin-to-cruise]

Your compressor in the master stateroom that runs a long time and doesn't cool well sounds like it could be low on refrigerant. It's working hard but there's not enough fluid to do the cooling.

The cycling problem in the salon could be a thermal overload at the compressor. This is a guess... The compressor on light at the control is applying power to the compressor. The auto shutoff features in the thermostat control should turn off that compressor light, so if they don't and it is still on it could be the compressor.

I had a compressor that was working hard like that with poor cooling and an AC contractor replaced it. Still had the same problem. He wanted to replace the reversing valve next so I did that myself. Turned out it was the reversing valve. That could be your problem too. Best thing to do is switch between cooling and heating by running the thermostat temp up and down. You will hear a loud hissing sound for about 3 seconds when the valve works properly. If the valve was stuck part way and leaking pressure like mine was you could see that high temperature.

Definitely get a set of gauges. They're cheap! Also get the special racheting wrench for the square drive pressure port valves (which turn backward- CW to open). If your pressures are in the 250 high and 60 low range you are OK. This is like taking your blood pressure at the doctor's office. Real basic but a very important thing to know.

[Bill Allen]

On the one if you have digital controls sometimes they get confused, turn off power wait and restart. Sounds like low freon on the other. Bill

[campbellde]

I second the low refrigerant diagnosis. The refrigerant not only cools the air, it also cools the compressor as well. The thermal overload is internal to the compressor and kicks it off at a certain internal temp. At a given point, low refrigent can not provide enough cooling to the compressor.


High pressure can cause the same symptoms. Malfunctioning seawater pump or clogged HE could cause this.

Dan

[Pascal]

thks guys...

no reverse cycle on these Ocean Breeze... so cant' be the reversing valve.
yes digital controls, but i checked and there is voltage at the comp. run terminal when the compressor stops.

water flow/pump is good. I disconnected each outlet hose to the sea chest to make sure they all had flow. I'm still going to flush them just because it's time to but i'm sure that's not the issue. I had each outlet hose in a bucket and flow was the same.

[Bill Allen]

I've just went through the same compressor issue i've got coastal climate digital controls, which I love. In the midst of topping off the freon the compressor would run for a little while and shut off, although the controls showed it running (it wasn't). Checked every control on the damn thing everything was fine. Thought since the controler is a compuer maybe a reboot would be in order. Shut the power down at the ac panel for a minute, totally removing electric from the control panel. Waited a minute or two repowered and they worked perfectly. Also cleaned the condensors and found a funny fan pattern in the aft cabin (would run high than low evey few minutes) also went away. Bill

[krush]

The compressor housing is usually going to be slightly warm to the touch. Feel the suction (return line) to the compressor. It should be cool and maybe even have a little condensation on it. The returning refrigerent is what cools the compressor, so if you do have enough in the system you will overheat the compressor and will not have the proper cooling capacity.

The cycling one is either because of a overtemp (it sounds like it is a lot hotter) or because of a low pressure or high pressure safety shutoff....it's hard to tell what your system has.

Some of the compressor will run very hot and not overtemp cuttoff unless they are on fire...or the overtemp safety is broken. It's hard to tell.

And fixin, please stop advising on the L60psi H250psi way of recharging. You'd be better off to say "charge the system untill you feel the suction line getting cold back to the compressor, but not the entire compressor housing getting cold"...and honestly, that is a MUCH better way to charge.

And a system low on refrigerant doesn't "work the compressor hard". The compressor gets hot, but quite to the contrary, it's actually "working" much easier and pulling less amps.


Cliff notes: get a set of gauges. hook them up and run the system for awhile and take notes of the readings and how they move up/down and come back here with them. Try to get water temp, cabin air temp, and coil temp (measure cold air in vent closest to evaporator).

[Bill Allen]

Actually depending on water and air temps the suction pressure can be over any 60-65 psi reading. Since my water temps are 75 and air was 80 I set mine at 75. There is a sheet in the op manuel which will give you both hi and lo pressures at water/air temps.

[Pascal]

i took some temp readings yesterday

on the master (the one not cooling very well and with the hot compressor, I'm only getting 71 air out... temp on the evap coils average 68/69, condensing tubes in the ER average 103

when it runs, the rear salon shows same temp as the fwd salon... air out around 61, evap coils around 60/62, condensing tubes around 130.

[Bill Allen]

When eveything is running well I get about a twenty degree drop in air temps in/out. When only one unit is running it takes forever to get any real diffrence in the air temps. It still sounds like you need to put a gauge on the suction and see what your getting. Considering where your at you should be in the mid 70's or more. Consult the chart and set it accordingly. Also I'd depower the ac side of the boat for a minute or two making sure the control has no power, I swear it worked for me, no more short cycling either the fan or compressor. Bill