My 2000 jeep wrangler A/C stopped blowing cold air ? It is blowing air but nowhere near as cold as it was. What could the problem b ? freon ?

Low pressure switch or clutch switch if assuming clutch is not engaging when cold air is not being supplied.

Was it getting cold before the compressor was changed ?
Could be a list of things including low on freon, restriction in the lines, cooling fan, restriction in air flow thru the condenser, etc.

your auxillary fan is not working. this fan is responsible for cooling the freon that is being circulated in your cooling system... check if there are any loose wires in front of the engine bay.

the auxillary fan is located right beside your radiator fan.

Heater blowing cold air,indicates towards low or no coolant or the coolant flow is getting obstructed or the heater core is clogged or hot to cold moving flap/ door is stuck in cold mode. There are many possibilities, that needs to be checked. Click the link below for step by step details:--- http://technoanswers.blogspot.com/2011/10/heater-blows-only-cold-air.html ---------- This should help.Thanks.Helpmech.

replace termastat

there are 2 lines coming off the compressor put freon in the larger of the two

Check coolant level

You have a leak in the AC system, have it tested and repaired.

How often has the coolant been changed? My only guess is that it hasn't and the hoses and the heater core are plugged up with goo and a flush is needed

This may be the AC compressor cycling switch is defective. It is located in the larger of the 2 AC lines coming from the compressor, it has a wire connector to it with 2-3 wires. To verify this is the issue jumper the connector with a small piece of wire and see if the compressor runs.