Air Conditioner Went From Big Blast to Small Blow

[Fly at Night]

Turned a/c on for the first time a couple of days ago. Was really putting out a good blast of cool air, especially when on high.

Today there is barely a breeze (when on high). I turned the temp. up in case it was overworking to 69F - still is barely putting anything out.

And help/hints?

[bellastream]

Evaporator coils could be frozen up this would block airflow.

[cwf]

What is park voltage? Check the plug on post for overheating! Try not to run until figured out. If on 30 amp you can test most any outlet for voltage.

[Pileus]

Mine does this a lot. Run the unit "fan only" for an hour or so to defrost the coil. Then you will have your full blast again.
Sure telltale sign of frosted up coils is a stuffy sound and poor air output--with no condensation dripping from the outside drain.

[TLBIJOU]

Which is usually caused by dirty coils that cause it freeze up. If the system has been opened and someone charge the Freon and overcharge it, this will cause ice build-up on the coils.
CLEAN THE COILS!

[Fly at Night]

Okay. Have a/c on "Fan only."

Trying to find link that will tell me how to clean coils.

[Fly at Night]

Do I have to get onto roof like this?????

Cleaning the AC coils - (Lots of pic's) - Sunline Coach Owner's Club

[gr.austin]

You are right to run the unit fan only for a while. If your unit is a heatpump turn it on heat set t'stat for as high as it will go and let it run for 3-5 minutes. This should defrost the coil very quickly.

two more possible problems:

1. Make sure the indoor air filters are clean. Leave out when in heating mode to speed up the defrost.
2. You need to check the wiring connections:
a. At the breaker. The screws should have about 50 lb-in of torque on them
b. At the unit. To check these you have to remove the indoor grill 6-8 screws on mine. You can then see the sloppy wiring. Find the non-metalic cable feeding the A/C it is usually connected with wire nuts. I have found that the wire nuts that they use are not suited for mobile applications and will vibrate loose very easily. Make sure the breaker is off when checking these connections. A crimp connection is the best when properly installed. However, in a pinch I like the Buchanan B-2 RED wire nuts. They are flexible so they conform to the wire insuring a good strong tight connection if properly installed.

Just to be on the safe side do a visual inspection of the outdoor coil to make sure it isn't plugged with leaves.

If making sure all is wired properly and coils are clean, the next probable cause for the freezing coil if that is what the problem is would be an under charge of refrigerant. An over charge would cause high head pressure and then shut down and then warm air blowing. But sense you said that the air flow starts out strong and then dwindles to a weak blow this is a classic sign of a frozen coil.

Please be careful when checking the connections to the A/C.

[JCWDCW]

Be careful about getting onto the roof. Use a blanket or big towel to protect the aluminum sides from the ladder. You can only support yourself on the roof where there are ribs. They are spaced quite widely. I was easily able to work from the ladder.

JCW

[Pileus]

Two BRAND NEW 15,000 btu units (This is TEXAS). Coils are virgin clean. Lots of humidity in the air due to recent weather events.

[Fly at Night]

Thanks for all your help.

But, I'm afraid the thought of getting onto the roof to look at the air conditioner makes me freeze!

Will try the fan only cycle again tomorrow, then see how it blasts.

[Fly at Night]

Originally Posted by cwf

What is park voltage? Check the plug on post for overheating! Try not to run until figured out. If on 30 amp you can test most any outlet for voltage.

I'm driveway camping - plugged into outlet in garage which is 20 amp, I think.

Is this too weak for a/c?

[paiceman]

Yes, for one A/C you must have true 30AMP, for two you need 50AMP. 20 is not enough.

[Fly at Night]

paiceman, the a/c also did this when I was plugges into 30 amps at RV park.
I will look into getting 30 amp outlet, though.

Anyway, did the fan only setting for an hour and tried it again this am. She is blowing hard and cold again. For how long? We'll see. Maybe I'll get lucky and the trailer will resolve the issue itself again.

[jcanavera]

Also be aware that if everything looks clean, coils freezing up can also be an indication of low refrigerant which may mean a leak.

I did have a freeze up on my SOB when it was new when I was down in Destin Fl. Air conditioner guy did weekly trips through the campground and stopped in to see me. He told me that running the fan at low speed in high humidity climates can cause the coils to ice. He told me to make sure the fan was in high speed to promote air flow. Did that and never froze up again while on that trip.

Jack

[Fly at Night]

jcanavera, come to think of it - the recent problem started after running all afternoon on low!

The first day I used a/c, was on high all day. No problem.

Thanks for telling us about your experience.

Holding my breath.....and the air conditioner is still blasting cold and hard.

[cwf]

Originally Posted by Fly at Night

paiceman, the a/c also did this when I was plugges into 30 amps at RV park.
I will look into getting 30 amp outlet, though.

Anyway, did the fan only setting for an hour and tried it again this am. She is blowing hard and cold again. For how long? We'll see. Maybe I'll get lucky and the trailer will resolve the issue itself again.

Sounds like a freeze up.. Did you have it on max cold? Can you set fan speed? If so, set high fan, but not as cool as you want it at first... Let the AC remove a lot of moisture from air then Drop Temp.

Make sure filters clean.

[Lumatic]

Originally Posted by Fly at Night

I'm driveway camping - plugged into outlet in garage which is 20 amp, I think.

Is this too weak for a/c?

Running an AC on 20 amps can damage the unit even though it initially seems to run OK.

[lewster]

Not really....... After all, it IS connected to a 20 amp circuit breaker at the trailer, breaker box........but I would ONLY run the A/ C and nothing else.

Full load running amps for the Dometic units are around 3 for the blower motor and 12-13 amps for the compressor. That totals 16 amps, and this is measured at 90 degrees F. at lower ambient temps, the compressor draws less than that.

Since the start spike of up to 50 or do amps is transient, super short and covered by the start capacitor. There should be no problem with a true 20 amp circuit.

Just be very aware of the size and length of any extension cords you may use. As too small a wire gauge will result on noticeable voltage drop.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[Lumatic]

[QUOTE=lewster;1636528]Not really...
Lew Farber

Not saying you are wrong. I am not claiming expertise, but the question if 20 amps is sufficient to run even a 13.5 AC has been asked on the forums a gazillion times. Every time I can remember the answer was no. If I remember correctly the claim was the initial start up draw put a strain on the compressor.