I got 4 Mitsubishi a/c units all working fine for 6 years.
My house has pre-drilled points for a/c units, and pre made drainage pipes leading to the outside.
While the 3 ac's drain through the pipes normally, one of the a/c's doesn't seem to drain anywhere (not through the pipes, not at the compressor outside and it doesn't of course have a separate drain pipe , none of them do, they use the pre-built ones).
There is no moisture on the walls so WHERE does the condensation drain on the 4th ac?
Thanks

Weird! Would seem the drain is clogged inside the case. Water pan could be tall enough to hold considerable condensate and fan is blowing a lot out through the condenser coil. I think poke up that drain a bit and see if you get a response. Otherwise take it out and do a look see inside for what's going on. Maybe it's low gas and not making much water.