Problem with ac/heater evaporation

I have a 1993 Toyota Camry. The ac/heater evaporation system is not working properly. Water is backing up onto the floor carpets.My mechanic has blown out the hose. The problem persists. What next?

Have you had any experience with this?

Does this water appear only after running the AC?

Tester

yes and now thatitis winter, it happens when I run the heater

Yes. and now that it is winter , it happens when the heater is running

It’s probably happening when you run the defroster rather than the heater as that’s when the A/C compressor kicks in unless it has acompressor switch that you have chosen to leave on. I suspect your mechanic didn’t get the obstruction out of the drain hose. That’s about all it can be. Have him try again for free, or try another mechanic.

The idea of condensation forming on a heater core is taking me a while to grasp. OP no one really uses the term “evaporation” when describing your problem, I think I know what you are trying to say but the word is “condensation”.

My mechanic says that he will have to remove the dash to find the problem…many labor hours seem to be involved, To old school…I was referring to the evaporator hose being clogged as the problem.
To.MG McAnick No, it happens whenthe ac is on or the heater is on; not the defroster.
Msytery???