I know the unit is old, hopefully the repairs today will carry me for awhile! Since I don't know anything(!) about air conditioning one has to rely upon what's said by the technician.
Response from Air Care Systems Inc.:
THANK YOU SO MUCH FOR CHOOSING US! WE HATE THAT YOU HAD 3 OTHER PEOPLE/COMPANIES WORK ON THIS UNIT AND WERE UNSUCCESSFUL IN GETTING IT RUNNING FOR YOU. GLAD WE COULD STEP IN AND HELP TO GET YOUR TENANT COOLING AGAIN! IN THIS CASE... THE 4TH TIME IS THE CHARM. KIND REGARDS, ANN POWERS, VP