[mkeith54]

When you say it is not working, which mode is not working. Have you lit the pilot light? For that matter did you pull a me and not have enough LP? My pilot would light but then go out when the burnner kicked in because the LP was low. Is the trailer totally level side to side and fore to aft? The older units are very finicky about this.
If you are running on electric check the fuses and ohm out the heater element.
Another thing to look for is green corrosion, the green comes from the amoninia leaking out. This is youmight surmise is not a good thing. If it has leaked you might be able to replace the cooling unit , but you may have to replace the entire unit.