Tropical guttering overflowing from aircon discharge

After our house was built, an alfresco was added along the complete length of one side of the house - this alfresco has a high gable roof of colourbond. The house roof is tiled.
The gutters are the tropical type with slits in the body of the guttering.

We had a few instances of overflowing gutters during heavy and/or prolonged rain and took remedial action to deal with causes - perforated metal gutter guards fitted to prevent leaf build up from neighbour's trees (!!) and the downpipes enlarged - this seems to have resolved the problem for the most part.
BUT, over summer, we noticed that when the evap aircon discharged, there was significant overflow along about 1 metre of the gutters - water pools on the decked floor and anything else in the vicinity of this section of guttering.
We think it would be too difficult (and expensive) to replace existing gutters so seeking advice for a simpler solution.
Thanks in advance.

 

You may need a spreader on the drain as it sounds lie it is overshooting the gutter. Got any pics?

Tools

 

Thanks for your reply.
Sorry no pics and can't test your theory as we're not likely to be using aircon any time soon (very cold here now).
The water might be overshooting the gutters but could also be due to large volume of water all at once and coming faster than the gutter/downpipe can handle.

What is " a spreader on the drain" and who could do this - a roofer, roof plumber or could a handyman do it?

 

All AC produces water which should discharge to gutters and stormwater. Plumber should advise. If i could guess ours inSydney may be 15 litres a day. 30 in summer.10 in mild spring,/autumn. None winter. Its humidity more than temp. AC drains varybl have plumber check gutter fall so it drains