Do you need brackets for outside wall installation for the frigidaire 15000 btu air conditioner.

googled:
"suburban air conditioner 15000-48254C966" and got specs right here:
http://www.adventurerv.net/coleman-15000-btu-roof-air-conditioner-top-unit-p-1332.html
good luck.

For an RV 15000 BTU air conditioner the size being maximum for 115 volts ac you will need to have a independent circuit breaker for it only and rated at 20 amps. The average amps depends on serveral factors like actual supply voltage somtimes 110 to 120 volts and wire size and length feeding the air conditioner. To answer your question the average Amps will be near 13 Amps. Click Here=>

Dometic RV Air Conditioner Installation Manual and Specifications
Click here for a photo of the Electrical Spects.=>

Dometic_RV_Air_Conditioner_Electrical_Specifications
If you have any questions I will be here to answer them for you, Thanks, Sea Breeze

The AC your landlord installed is rated at 8000 btu which is way too small for 900 sq ft. You need at least a 15000 Btu Air conditioner and a 'well insulated' house to be cool.
A good rule of thumb in the AC business says you need 1 ton (12000 btu) of Air conditioning for every 600 sq feet (if the house is well insulated) - if not - then you will need 1 ton (12000 btu) for every 400 sq feet.
So, if you have 900 sq feet and the house is well insulated you should have at least a 15000 btu unit.
If it's not well insulated you will need 24,000 btu.

15,000 BTU stating current 18 to 20 amphs. And running amphs will be around 6.5 to 7 amphs.

Yes... no problem... just need to use cardbord of something to seal off the open spaces around it...

heatman101

What are the walls made of? Some details there would better help us t advise you on what to do. Also, this being a window unit, why not just mount it in the window?

Whinny noise is probably motor which needs some motor machine oil (hardware store).

Freezing is probably caused by bad de-icing switch or poorly insulated de-icing switch.

If you want to further pursue, let me know.

It must be installed in a window openeing or through the wall.
A load bearing wall is no problem.
Cutout the opening larger than the unit and install a header in the wall cutout.

It is called a mounting kit and can be purchased at Home Depot, Lowes, or an appliance store.

Purchase an "L" shaped shelf bracket (heavy duty of course) and fasten it to the outside wall under the window. You should be able to now use the support bracket against it. You can even get special plant hangers that will serve the same purpose. I have seen many people do this and it seems to solve the problem!