I have a AR 48-1 Goodman Furnace where can i get information on it? Size..etc

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.

There is no right answer for that. The bigger the better, ideally 4 ft long by the dimensions of your unit supply.

If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

http://www.goodmanmfg.com/Portals/0/pdf/SS/SS-GMH95.pdf

Power is there, or no lights would blink. Steady blinking or flashing three times, stop, three times Etc

not much to go on.dianogstic light will tell you whear to start.these are sensitive to polairty.check to confirm hot 110 is black wire.I put one in that had on off switch on gas valve.turn on.did you bleed air out of supply? did furnace try to light?

if it is a fuel furnace the pump may have air in the system. here is a web site that will give you the information you will need to to help you fix the problem, there is a manual that will take you step by step to resove the problem, if you need more help understanding the troubleshooting of the system post to this e-mial you will get.
http://www.aircondition-units.com/pc-72-25-gms90703bxa-gas-furnace.aspx

JUST SAND THE FLAME SENSOR LOCATED IN FRONT OF THE LAST GAS PORT.

What part of the country?
How many square feet in the house?
Insulation?
Single pane glass?
Many factors should be considered by a professional.
However if the old unit worked OK, a new 80% 70,000 unit will most likeley replace a 24 year old 60-70% 75,000 unit.

If your running gas heat it's 5/8 3/8 tubing.If it's elec. heat it's 3/4 3/8 tubing. Etheirway 3/4 3/8 works for both. Use 6 wire for tstat from tstat to furnace or air handler, and you need is 2 wire from condensing unit [outside] to furnace or air handler or anything more than two.

At what point does the pilot blow out? Within 5 seconds after it lights or when the room air blower turns on?