New owner 1987 Wellcraft St Tropez 3200 noise in AC, shower not draining and toilet not flushing well

[Sparks]

Hi! We are new to cruiser type boating and was cleaning the shower to find out it wouldn't drain, installed a new shower sump...nothing. Are we looking over a valve before the sump pump that may be closed? I think we've figured out that the water wasn't on when we tried to flush, turned on but seems to still have difficulties flushing..we have pumped out but couldn't tell if anything came out, then found a macerator...what am I doing wrong? Last question..i just noticed the AC was making alot of noise and didn't notice the water draining out that I originally saw the last time it was running properly but I could be mistaken I'll follow up with you on that. Any help will be appreciated!

[Billm]

No valve in line between shower and sump pump. You must have a clog. So disconnect shower drain line at pump and pour some water into shower. If it does not come right out, try using a snake back to shower. You may have to poke out the drain fitting itself to get water flowing out.
If your toilet is not flushing, it needs rebuild kit. Now as regards pump out, make sure your y-valve is in the correct position. If you are legally pumping overboard, the holding tank needs to be pretty well full to prime the macerator pump. You can tell from the sound if anything is coming out. If there is just a “whirring sound” then it is not working. It should be more like a heavy bubbling sound that changes when the tank is empty. If still not working, then you have a build up of solids at the bottom of the tank. Disconnect at the y-valve and snake back to the tank to free it up. Be sure to keep the end of the hose higher than the tank or you will have unpleasant surprise when free up occurs.
The holding is only 13 gallons which is a problem. I recommend installing a holding tank level guage. I like the one by Scad Technologies.