A/C coils keep freezing up...suggestions?

jjherber

I have a 2004 270FV with a Marine Air A/C/Heat unit.  This past summer, the A/C unit coils kept freezing up and blocking the air flow on the vent.  Had to either use a hair dryer or turn on the heat to unfreeze...then would work fine...temporarily.  When the unit is operating normally and coils not frozen up, the unit works great and will cool off the cabin nicely.  Strainer is clean and unit has great water flow / stream.  I'm guessing that it needs to be recharged with refrigerant...but was wondering if anyone else has experienced this problem.  By the way...the screen / filter is clean and there is nothing blocking the opening to prevent airflow to the coils.  Any suggestions?  Thanks...Jason

randy56

@jjherber, welcome to the forum, sounds like its low on Freon, 

Handymans342

There's only two things that make a coil freeze that is low on freon or the return air is blocked

Dream_Inn

I agree with the other comments, but will add that you can change the parameters so that it will defrost it every hour for amount of time you select (i.e. 5 minutes).  What it does, is run heat cycle every hour for a short period and defrost.  You may also be opening the cabin door often, causing excessive humidity.

Ian

I found the same with freezing up when cranked down and the humidity is high. Haven't checked the refrigerant level though so maybe I should next season.

jme097

Lack of air flow or low on gas. 

PartsMan

I had the same problem. Got a couple of small fans to help move the air around. Problem gone!

Handymans342

jme097 said:

Lack of air flow or low on gas. 

Why does everyone keep repeating me? LOL

Liberty44140

X3 or X4 (echoing Handy of course) on air flow. My in laws power boat kept freezing up and the issue was the air filter on the intake was full of tree cotton from the spring drop!

jjherber

Appreciate the comments. Through process of elimination, I have to believe it is low on freon. I will try that first and see if that corrects the problem. Thanks for the suggestions!!

davidbrooks

Adding Freon isn't a do it yourself job.  I would recommend getting a local AC guy to come out.  I would not go to a local parts store and get a can of Freon.  It needs to be the right pressure and needs to be checked on the low side and high side of the compressor.  Most folks using the cans either let more gas out than in or add in contaminants to the system.  It is worth the service call.

rasbury

That's what u say...could be an expensive lesson...

bry1429

Your Freon should never just go low, if it's ever low that's an indication of a Freon leak somewhere. 

Dream_Inn

If it's blowing cool air, it's not the Freon. I'm betting you should try messing with the settings first.

jjherber

Thanks.  I wouldn't mess with the freon myself....would definitely have a professional handle it.  Dream_Inn...I will try the different settings first to see if that does help.  I did notice that it was more prone to freezing when I would arrive to the boat and it was 90 degrees and high humidity and I would turn on the a/c on.  Seems like I would have to "step" it down 5 degrees at a time rather than just set it at 72 degrees and let it run.  Like it said, when it runs, it blows cold air but then when the coils freeze up, the air flow virtually stops.  Great ideas.  I appreciate all your suggestions.

raybo3

Dream_Inn said:

If it's blowing cool air, it's not the Freon. I'm betting you should try messing with the settings first.

Sorry DI I dont totally agree with you. If your low on freon you will get some cooling then it will freeze. I do agree that it could be a setting and he should try that first.

Dream_Inn

Well, with the added comment that it happens more when he first gets to the boat, especially at 90 degrees and trying to drop it down to 72.  I know believe even more the change in settings will work.  I'm betting that thing is running more than hour at full cold when you first get there.  It needs to have a break and the change in setting will defrost it extremely quick.  I also agree that air flow could help and definitely keeping things closed up- not going in and out continuously (and covering hatches from the sun initially as well).  I know when we first get to our boat we are loading up going in and out quite a bit.  Most of the time it's a Friday evening so the temp outside is starting to cool off (or if it's my Friday off then I'm there in the morning)

Liberty44140

There is a master reset process in the marine air manual to re set to factory settings. Maybe that is step one? 

rasbury

I know there is a re calibration for the ambient temperature which was wrong with mine when we first purchased- you can google it as I don't think I printed anything out and it was simple. Heat worked real well and the air would not cool. Could easily be the other way as well...

califco

Run a self diagnosis test, press the power button while the power is on.
I agree with calibrating the ambient sensor as well, hold the power button while the power is off, P1 will apear, move to P5 using the arrrows, adjust the temperature to the ambient temperature. Also check The setting on P8, this is the deicing cycle, ensure it is not off, default should be 1.

jjherber

Thanks califco. I will definitely try that when I put her back in the water. Still a little early yet here in Chicago area but we are only about a month or so away, optimistically speaking!!!