20 Most Recent American Standard 4021 White Cadet 3 Toilet Tank Lid - Page 3 Questions & Answers

Run a short snake thru the line. Somewhere between the drain and the tee into the line with the sink is a clog.

Be sure to pull the plunger all the way up when diverting the water between the the tub and shower if ti keeps giving you a problem it's faulty

depress and release button and whirlpool will stop

It's possible you installed the valve upside down, all values should be labeled in some way marking either hot and cold or it will say the word up where the riser tube port for the shower head is. If that's not the case remove the tub spout and check for any obstruction sometimes during tile or constructing debris can get into the pipe for your tub spout. Lastly the diverter on the tub spout could be bad. Try a new tub spout