Kitchen Large Electric Appliances - Dishwasher NOT draining

We just moved into a used house that has a Whirlpool dishwasher and it's not draining. It had a pressure valve piped to the little spewer on the sink, but I unhooked it because it leaked water all over the sink/counter. Anyway, I ran the line directly into the disposal and bypassed the valve. What and how can
I check out why it's not draining. I do hear the pump running and it may just be slow draining. My old unit worked fine piped this way, so what gives? Thanks for any suggestions.

Was there anything hooked to the disposer before? If there wasn't the plug needs to be knocked out of the disposer so the dishwasher can drain. Check for any clogs. If that doesn't work, you can have the dishwasher drain hose in your hand and hold it into a bucket, then cycle the dishwasher to drain and see what happens. If it still doesn't drain, things need to be looked at either a clogged hose, or clog in the motor/pump area. If this dishwasher uses a single motor/pump and does not have a seperate drain pump, I have seen these clog at the little plastic tube that comes out, that the drain hose is hooked to. There is a check valve housed in there that can get clogged with debris. The tube unscrews from the motor/pump and can be cleaned out.

Thanks gdoug...I'll unplug the line that goes to the disposal and make sure it's knocked out. Yes, there was a 1" black hose going from the pressure relief spewer to the disposal and a smaller plastic drain line that came from the dishwasher also going into the spewer. The part is about a foot long and looks like an inverted Y. I just unplugged the smaller line and crammed it into the bigger one, then ran into disposal. That's the way it was set up and my old house. I guess I have to pull out the dishwasher from under counter....fun.

I suppose I have to access the line from under the unit? I might be able to get the shopvac and suck it out from the drain that's at the bottom in the tub part. I never mess with dishwashers, so maybe I can find a diagram online. Thanks again.

Good news, the dumba$$ that had the house built didn't know to take out the drain plug from the disposal. I removed it and punched it out and it works great. I did bypass the spewer on the sink though. Wife is happy now.