There's goodman air handler in attic space, think it is CK36-1A ,of purchased home. i need a filter size, someone just put in green cut out media.

The model number you listed is for the outside unit which does not have a filter. The indoor part of this system (the furnace or air handler) is what has the air filter. The size varies because the installer usually makes a bracket to hold the filter when the furnace is installed. Need to locate the filter and replace it with the same one. Size should be marked on the old filter.

If this is a case coil, they do not have a filter area, the filter is normally either installed in the return air grill or needs some type of filter installed just upstream if in a down air installation in a closet. If it attached to a furnace, there is a space provided by most manufactures for a filter installed just before the air return. If the furnace is in the attic or in a crawlspace, I never install a filter in these areas, but put a return filter grill in the return path.
Hope this helps

THE FILTER IS THE AIR FILTER . IN THE RETURN AIR GRILL EITHER IN FLOOR OR IN THE WALL / SOME ARE INSTALLED IN THE UNIT IN THE AIR HANDLER COULD BE INSIDE A CLOSET OR ATTIC OR UNDER FLOOR / FIND AND CHANGE IT . IT WILL BE WHERE THE AIR IS PULLED INTO UNIT ON RETURN SIDE AS I SAID SOME IN FLOOR GRILLS , SOME IN WALL GRILLS . SOME IN CEILING GRILLS . JUST TAKE OUT AND GOTO LOWES OR hd GET SAME SIZE AND REPLACE

There are a few variables that determine the size needed to cool your home - the size of your home, type insulation, are just two. I have a 2600 sq ft home - about 1300 sq ft per floor. I choose to cool the entire second floor (bedrooms and baths) and two of the largest rooms on the first floor (kitchen & living room) via flexible ducts from an air handler installed in my attic. My house was built in 1960, and at the time had electric heat. This means it is fully insulated. I replaced all the windows with energy efficient types, and vinyl sided. I installed soffit, ridge and gable vents to keep my attic well ventilated. I can cool my house in Boston, MA to 70 degrees (when it is 85 degrees inside) with a 4 ton unit in a little over an hour with no problem (one ton of cooling is equal to about 12,000 BTUs). Your condenser should not run non-stop. If it is not cooling then it is not a thermostat problem, but could be a gas charge problem. If you haven't paid the contractor in full yet - that may be the reason why. The contractor should know how much cooling you need for the space you have and installed a properly sized unit. Make sure your air filters on the return are clean and replaced regularly. Call the contractor and explain the problem - he should be able to solve it for you very quickly.

it could be an air handler in the attic, do you have gas or ele. some are built into the water heater if it is gas, do you have base boards running around the bottom of your floor or air vents with am ac condesor outside if this is the case it could be either the crawl space or attic

If you have a shop vac (wet vac) I suggest finding the drain outlet and sucking the restriction out. However if you don't then you need to open the air handler (coil) and pour about a cup of Bleach, not drain cleaner in to the coil drain pan. The restriction is likely in the trap ( U shaped piece of pvc). Good luck!

The Air filter should be located under a grid in the ceiling somewhere in the house. That is where the air in taken and returned after it passes thru the air handler in the attic. There has to be an access to the attic in order to service the air handler if needed. That is Code. Your system, I presume, is a "split system" with the condensing unit outside and he air handler in the attic...

is the unit in a closet, attic, or basement. if the unit is upright it would be in the bottom of the air handler if you can't find a wall return air grill. in the attic it may be in the end of the unit where the return air duct attaches to the unit. if no luck then someone has removed it and failed to install a new one hopes this helps...

If your rooftop unit is self contained with no pipes leaving it except the condensate drain line there should be a narrow removable panel to access where the filters are located. If you have three pipes exiting the roof top unit two will go to an air handler located in the attic of the home. The filters will be located in the air handler.

These guys list the actual sizes of a good selection of goodman filters - just measure the old one or the space where it should be and match it to the right filter(should be a fairly tight fit). http://www.filters-now.com/products/dgb.html#skipmenu and this site describes what the different filter types available are http://www.oxyclean.com/goodman.html Hope this helps :)