Reply
 
Thread Tools Display Modes
 
Old 04-24-2016, 07:41 PM   #1
Member
 
City: Lake Charles
Country: USA
Join Date: Aug 2015
Posts: 17
Air Conditioner cycling often

I have a Dometic Airrr system in my 2004 Mainship Pilot II.
It seems to be cooling well, but it cycles on and off very often.
Also, the temperature reading seems to be higher than the actual cabin temp.
When the unit is running I can check the AC outlet vents with my laser temp gun and it reads around 45 degrees, which I'm told is good.
I have to set the cabin temp to around 67 degrees to get it to feel comfortable inside. When the unit reaches this temp, it cycles off, which seems normal, but then it will cycle on and off at approximately 15-30 second intervals to maintain
the temp.
Since the unit is under our berth, it is difficult to sleep with the constant cycling.
The raw water pump seems to be operating normally.

Someone suggested the thermostat may be bad. Any thoughts are appreciated.
__________________
Advertisement

altouchet is offline   Reply With Quote
Old 04-24-2016, 07:43 PM   #2
Member
 
City: Lake Charles
Country: USA
Join Date: Aug 2015
Posts: 17
Air conditioner cycling often in my Pilot II

I have a Dometic Airrr system in my 2004 Mainship Pilot II.
It seems to be cooling well, but it cycles on and off very often.
Also, the temperature reading seems to be higher than the actual cabin temp.
When the unit is running I can check the AC outlet vents with my laser temp gun and it reads around 45 degrees, which I'm told is good.
I have to set the cabin temp to around 67 degrees to get it to feel comfortable inside. When the unit reaches this temp, it cycles off, which seems normal, but then it will cycle on and off at approximately 15-30 second intervals to maintain
the temp.
Since the unit is under our berth, it is difficult to sleep with the constant cycling.
The raw water pump seems to be operating normally.

Someone suggested the thermostat may be bad. Any thoughts are appreciated.
__________________

altouchet is offline   Reply With Quote
Old 04-24-2016, 08:20 PM   #3
Guru
 
Bacchus's Avatar
 
City: Seneca Lake NY
Country: US
Vessel Name: Bacchus
Vessel Model: MS 34 HT Trawler
Join Date: Nov 2014
Posts: 1,407
Do you have the A/C manual?

From the manual
"Program Cool only and cooling only will be supplied. The
cabin temperature will be maintained within 2F (1.1C) of
set point. "

"P-5: Temperature Calibration
Use this feature to calibrate the ambient sensor. Select P-5
and the ambient temperature appears in the display. Use
the Up and Down Buttons to set the correct reading. The
temperature in the display will increase or decrease as
required. "
__________________
Don
MS 34 HT Trawler
"Bacchus"
Bacchus is offline   Reply With Quote
Old 04-24-2016, 08:23 PM   #4
Senior Member
 
Duvie's Avatar
 
Join Date: Nov 2011
Posts: 177
Sounds like a low suction issue

If the unit has a low suction cut off the unit would cycle as described for a few reasons. If the filters are extremely dirty or something else is restricting air flow like closed dampers or a crushed supply duct. The unit would also do this if it was low on refrigerant. If the unit does not have a low suction limit then the above does not apply.
Duvie is offline   Reply With Quote
Old 04-24-2016, 09:37 PM   #5
Guru
 
djmarchand's Avatar
 
City: East Greenwich, RI
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,877
I agree. Something is causing it to trip out every 15 seconds: low suction pressre, high head press, etc. Usually there is a diagnostic code indicated in that case.


David
djmarchand is offline   Reply With Quote
Old 05-05-2016, 11:05 PM   #6
Veteran Member
 
LongJohn's Avatar
 
City: Watts Bar Lake, Tn River
Country: USA
Join Date: Apr 2013
Posts: 65
If the unit cools normally to its set point, then it is unlikely a refrigerant problem. There may be a 'remote' thermostat sensor that is dangling somewhere in the air flow path. The remote sensor is the primary sensor and will override the sensor in the control unit on the bulkhead. If like mine, the remote sensor was taped directly in from of the unit's air intake under the bed. Mine was being impacted by hull temperature. Unplug the sensor from the circuit board and control will shift to the bulkhead control unit sensor. Then you can calibrate the control unit per Don's suggestion.
__________________

__________________
LongJohn
LongJohn is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 06:29 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012