Changed my garbage disposer several months ago. Hooked up the lines like the instructions showed. I have a double bowl sink with the air gap emptying in to the right sink. If the sink stopper is plugged into the drain in the right sink, the dishwasher puts water through the air gap. If the drain is open in the right sink, the dishwasher does not put water through the air gap.

I have did not have this issue before I changed the garbage disposer.

Any suggestions would be helpful.

Changed my garbage disposer several months ago. Hooked up the lines like the instructions showed. I have a double bowl sink with the air gap emptying in to the right sink. If the sink stopper is plugged into the drain in the right sink, the dishwasher puts water through the air gap. If the drain is open in the right sink, the dishwasher does not put water through the air gap.

I have did not have this issue before I changed the garbage disposer.

Any suggestions would be helpful.
I'm unsure exactly where the hose from the counter top air gap's connected to. Is it to the disposal unit, (see image) or to a branch tailpiece?(see image). Let me know. Tom

It is hooked to disposal unit not tailpiece. The slope to disposal is not as steep as shown in image.

Is it safe for us to assume you knew about the knock out plug in the disposal and have removed it completely, Just checking.

My next question was going to cover the knock out plug. Bob just beat me to it. Remove the hose from the disposal and check to see if it isn't blocked. If it is then this is a "knock out plug " and simply whack it with a hammer and screwdriver to remove it. Be sure to retrieve the plug before operating the disposal. Good luck, Tom

I had a bad disposal that acted a bit like yours. The owner installed it himself and hammered a scrwe driver againist the knock out. They are very much like a knock out on an electrical box, they hang by two tabs and the rest of the circle is cut. The screw driver broke one tab and the other acted like a hinge with the knock out folded back. Worth a peek.

There is no knock out plug on my disposal. It has a one inch ridged pipe which the hose fits and is then clamped. I removed the hose and ran water from the air gap on the sink through hose. Very little came out.
I fished down the sink air gap with a plastic piece I use for cleaning sink drains.
I also reamed out the hose and removed some slime from the walls.
The hose is not kinked but it does make a 90 degree turn to fit on the disposal.

Kozsa, I think we need to ask just one more question. That short pipe sticking out of the disposal, the knock is about 1" down inside that pipe and is not easily seen unless you know where to look. I have never installed a dispoal that did not have the pipe and the knock out.

I reamed that pipe to a depth of two + inches. No plug.

Could the hose be kinked from that 90 degree turn causing back pressure?

Hose isn't kinked. After cleaning and reinstalling hose, the dishwasher ran without any water from air gap. Thanks to all of you for your advice. All was helpful.

Koz,
What's the brand name of your disposal? You say that in place of a plug the pipe was capped off.

If the sink stopper is plugged into the drain in the right sink, the dishwasher puts water through the air gap. If the drain is open in the right sink, the dishwasher does not put water through the air gap. This makes no sense to me. You say you're discharging into the disposal? Try this. Disconnect the hose from the disposal and put it in a bucket and cycle the washer. Does it drain through the air gap now? Let me know, Tom

Kozsa, Tom and I have been hesitant to make the next suggestion because it can start two camps of thinkers to start a debate. The air gap may or may not be code in your town. However, most dishwashers can be installed without an air gap and will work just fine as long as you make the drain hoes to form a very tall loop between the machine and the disposal. The air gap is there to stop back siphoning into the dishwasher, the loop does a nearly equally good job of preventing back siphon. You could always abandon you gap, maybe turn it in to a hand soap dispenser or install a chrome cock hole cover.