A/C quits underway

B

Boatdreamer

Well-known member
Joined
Jan 15, 2012
Messages
266
Fluid Motion Model
C-28
Non-Fluid Motion Model
17 Keywest
Vessel Name
Gratitude
I have a strange problem. Our a/c will run all day and all night on shore power or gen power while at the dock or anchored out. If I have the a/c running on gen power while underway, the a/c will quit after 35 to 42 minutes. It doesn't show any code on the display, it just stops working. The Mase 2.7 just keeps humming along just fine, but the A/C won't start back-up for awhile. I have check the strainers for clogs, all clear. I have noticed the newer R 27 has a larger sea water pump and larger sea strainers for the A/ C, could our smaller pump be overheating? The Admiral refueses to use the boat until this issue is fixed, she had heat exhaustion the last time we were out. Our dealer had a tech onboard and he said it could be an airflow problem but didn't fix anything. That doesn't explain why it works fine when we aren't underway. Any ideas?

Tim
Gratitude
 
Don't know why you are not getting any codes. When there is an issue you get a code on the thermostat. Either a low water flow, low voltage etc. I am suspecting that it may be a water flow issue since it only happens while underway. When you wait the 40 minutes and then it starts up again are you still underway? Was the tech from the dealer or Dometic? I would say a Dometic tech would be much more capable of resolving your issue. I found them to be very responsive when I has an issue with my unit. They had a tech drive all the way down to Key Largo and he took care of my problem. If you are in the Stuart area I am sure it will be much more convenient.

Let us know progress as it develops. In the meantime a Tom Collins and raft with a drink holder is in order for the Admiral.
 
Just a thought... Try using A/C with generator while at the dock and see if the sAme thing happens then you will know if power or water flow.
 
Boatdreamer,

Your comment that caught my attention is, "...The Mase 2.7 just keeps humming along just fine, but the A/C won't start back-up for awhile."

That statement suggests that the A/C starts working again on its on after some time period. If this is true, then I suspect you have an icing issue. Assuming you have the Dometic A/C, check out this section of the Passport I/O Digital Control (for DX systems) manual - Dometic Marine Rev. 20091102 L-2231 English:

"P-8: De-Icing Cycle
The de-icing cycle prevents ice build up on the evaporator coil during extended periods of cooling operation. Installation variables such as grille sizes, length of ducting, insulation, and ambient temperatures determine the run time required to achieve set point. Factors that substantially increase run time include operating the system with hatches and doors open, and programming an unrealistic set point (e.g. 65°F/18.3°C). Such situations can cause the evaporator to form ice on warm humid days.
• For software revision A13 and older, de-icing is accomplished by switching the reversing valve into Heat Mode while the system is cooling. The valve remains energized for the programmed cycle time. The cycle is programmable to “OFF” or to a period of 1, 2, or 3 minutes.
• For software revision A21 and newer, de-icing is accomplished by closely monitoring the room air temperature in 10-minute intervals during a cooling cycle. Depending on the parameter value and the change in room temperature during these monitoring intervals, the control performs various actions to prevent ice from forming or to melt ice that has already formed. This is accomplished by short compressor shutdown periods combined with a one-speed increase in fan speed, and by periodic Heat Mode cycles with the fan turned off.

The parameter setting for the de-icing feature depends on whether you are using the optional alternate air-temperature sensor or the display’s built-in room air-temperature sensor. Installation of an optional alternate air temperature sensor (located in the return air path) greatly increases the effectiveness of the de-icing feature, and this option should be considered whenever the display sensor cannot read the room temperature accurately.
• If using an optional remote air-temperature sensor, set this parameter to “1” to turn the de-icing feature on, or to OFF to disable.
• If using the display’s built-in room air temperature sensor, this feature has two selectable behavior modes. Both modes attempt to compensate for any temperature discrepancy the display sensor experiences. (Although discrepancy is not typical, installation variables such as where the display is placed inside the room—near an open door or in direct sunlight—can affect how accurately it reads the actual room temperature.) Set this parameter to “1” to assume the display sensor may be reading the room temperature as much as 5°F (2.8°C) greater than the actual evaporator temperature (standard). For more extreme installations, set this parameter to “2” to assume the display sensor may be reading the room temperature as much as 7°F (3.9°C) greater than the actual evaporator temperature. The setting of “2” should only be used if a setting of “1” does not prevent evaporator ice from forming."
 
The only thing I can think of that would make it shut off without a code would be if the AC thought it had reached the temperature you set. Perhaps water is causing an open/short? Another option is that the signal is being sent to turn on the compressor but faulty wiring is causing the signal not to reach the compressor. I think you would get a code on this one though.
 
Dale,
When in deicing mode the A/C still operates the only difference is that it actually will go into the heat mode so that the evaporator coil heats up and defrosts the ice. I am assuming when he says off, it is not running. So perhaps a more succinct definition of "off" will help.
 
I have experienced a similar problem with the A/C on my R25. Occasionally when under way (usually on a hot humid day) the A/C will just quit blowing cold air. The A/C fan is still working, no codes are set on the A/C display, the temperature in the boat is well above the thermostat setting, but the unit acts like it has reached its target temperature. The compressor just cuts off. Thus far I have been able to clear the problem by powering the A/C unit down and then powering it back up again. I did have this happen once at dockside on a hot humid night when running on shore power but all other occasions have been while underway when running on the generator.

I have always assumed this problem was caused either by a faulty thermostat that is slowly going bad or a defrost cycle built into the A/C unit that is not mentioned in the literature.

Since I can clear the problem by cycling the power, I have not investigated it further.
 
Thanks for all the responses. The A/C has never just shutoff at the dock, shore power or gen power, just underway. I"ll be taking the boat out this week, I'll check and see how long it takes to come back on after it shuts down. When it does shut down, the fan and compresser are both off, but it still displays the temp inside the boat. I've tried to restart it as soon as it shuts down, but nothing happens. I let it stay off for awhile then it will start up again. The problem then is it's so hot inside, the A/C can't get it cooled off before the next shut down. I do like knotflyings idea though, but with the South Florida water managers draing Lake Okeechobee, I wouldn't put my big toe in our local waters now!!! I'll try to get more information this week. I thought about the de-icing issue, but wouldn't that happen at the dock or at anchor too?

Tim
Gratitude R27
 
Ken: A power cycle is the normal way for clearing and resetting computer electronic ECUs/Chips to their proper settings. I wonder if this is what causes your A/C to behave properly after a power cycle ?
 
Tim,
Did you try turning the breaker off to the A/C so it had no power and then see if it would start up? I have found that the controller is very sensitive to any minor electrical changes. Perhaps when underway the genset has such a variation in power wave frequency and the controller is kicking it out. Turning power off to the A/C should reset everything and perhaps it will restart. This won't solve your problem, but it may start isolating the cause.
 
I have experienced similar behavior. I had several conversations with Andrew and the Dometic rep., and Dometic sent me a new control unit with the newest software. This did NOT fix the problem. We agreed that the AC thought it was iced up, when in fact it was not. The problem is the software algorithm that Dale777 described so well. If the temperature sensor does not detect a lowering trend in the temperature after some period of time, it concludes that there must be icing and turns off the AC in favor of a heat cycle. Note that this indirect method of determining an icing condition is easily fooled. For example, if the sun happens to be shining on the temperature sensor, it may not indicate cooling and will then decide that it needs de-icing even if it is really working just fine. The solution, at least in my case, was to go into programming mode and disable the de-icing feature. The instruction manual tells how to do this. Disabling de-icing means that you must be alert to the possibility of actual icing and be prepared to shut the unit down manually until the ice melts.

-- John H
 
Knotflying and Baz, next time it happens I'll turn off the A/C breaker and try to start it back up. Now I'm wondering if I have a lose wire somewhere. Thanks for the tips. I'll report back as soon as I try some of your ideas. This has to get fixed, as my warranty is just about up. We also have some trips planned for the rest of the year and the southwest Florida rendevous in February.

Tim
Gratitude R27
 
Sometimes mine when using dock power will do the same thing. If I turn off the breaker and wait about 1 min and turn it back on all is good .. Didn't dig any deeper ... It works all day after that
 
Irish Mist":1pqwz08s said:
Sometimes mine when using dock power will do the same thing. If I turn off the breaker and wait about 1 min and turn it back on all is good .. Didn't dig any deeper ... It works all day after that
Click to expand...

It sure sounds as if the A/C unit has electronic gremlins at work. 😉
 
After thinking about everything said, I think the de-ice feature might be the problem. John might have hit on something about the sun hitting the control panel. When we are docked, I usually have the screen on the windows, so the sun doesn't hit the control. All good information, thanks. I'll let everyone know what happens.
Tim
Gratitude R27
 
We got the A/C problem fixed!!! Here's what I learned. First thing is don't panic, let the onboard systems do their job. When the A/C quit I would shut the system down BEFORE it had a chance to thow a code so the problem couldn't be diagnosed. Tommy from Seagate Marine and I took Gratitude out, he kept an eye on everything while I drove. After about 40 minutes the A/C stopped working just like every other time. He left it on until it sent a code of HPE, low water flow. He waited a couple of minutes and restarted it. Everything looked good, except the sea strainer was only half full and the amount of water coming back out was much less. At that point it was determined that the A/C was fine but there was a water flow issue. Our boat is an early 27 with the smaller sea strainer. He installed a larger sea strainer and educated me on how the de-icing process works. We spent this past Thursday and Friday on the boat with no further issues. Thank you Tommy, now we are cool again and I'm a little bit smarter about how our boat works. Thanks to all that responded with ideas about fixing our issue.

Tim
Gratitude R27
 
Here's the model number for the new sea strainer: Groco WSB-750. It worked very well without interfering with anything else on that side of the engine.
 
Boatdreamer":11tpawf0 said:
We got the A/C problem fixed!!! Here's what I learned. First thing is don't panic, let the onboard systems do their job. When the A/C quit I would shut the system down BEFORE it had a chance to thow a code so the problem couldn't be diagnosed. Tommy from Seagate Marine and I took Gratitude out, he kept an eye on everything while I drove. After about 40 minutes the A/C stopped working just like every other time. He left it on until it sent a code of HPE, low water flow. He waited a couple of minutes and restarted it. Everything looked good, except the sea strainer was only half full and the amount of water coming back out was much less. At that point it was determined that the A/C was fine but there was a water flow issue. Our boat is an early 27 with the smaller sea strainer. He installed a larger sea strainer and educated me on how the de-icing process works. We spent this past Thursday and Friday on the boat with no further issues. Thank you Tommy, now we are cool again and I'm a little bit smarter about how our boat works. Thanks to all that responded with ideas about fixing our issue.

Tim
Gratitude R27
Click to expand...

Was it the Vetus 140 strainer that wad replaced? thanks.
 
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