poor seal

Question: I had a clean and check done on my ac. The company’s tech that did it said he needed to check the internal temperature of the furnace inside the house. He then pried open the metal casing of the unit to stick a thermometer in at various points. Unfortunately, he did not do a good job of replacing the seams (big gaps). He instead put aluminum tape over it. More tape was added by additional techs. But the unit immediately produces condensation when turned on. Water forms when left running. Is this normal? Should the unit have a better seal? What should they have done?