You may be seeing leakage from the condensate drain, which could indicate a leaking evaporator. Happened to me. The refrigerant and oil can come out there and leave a puddle on your garage.

Obviously you need someone to accurately diagnose this problem before you'll know what to do about it. If if is a bad evaporator, that's a pretty big repair.

Good luck, and do a search on "evaporator".

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Steve
'93 400E