Is it possible that air in the line could blow the cartridge on a Moen single handle shower/tub faucet? Mine no longer works after having the water off in the house for a couple of hours. I have no pressure at all (small drips) when I turn the tap into the full position.

It is probably not air issue but sediment type issue if you shut a shut off off. This does involve both tub and shower pressure... yes?

Here, I would start by shutting off water to valve, then using screwdriver remove the access plate and then you will see a copper type clip on the face of the moen stem. This clip needs to be pulled up and out ( I use a small screwdriver) to release the stem assembly.

Then, pull the stem assembly out (pull forward.. kinda hard... I use pliers on the cartridge end and give a yank... usually works).

Then, observe the stem assembly and the interior body of the valve... anything obvious?

If nothing obvious I would then pulse the hot and cold water on to see if I could release any debris from the valve body (NOTE... here you can confirm water pressure is present at valve... if not, problem is further back). Then, being sure to align cartridge same as I took it out, I would re-install the cartridge and the clip (this can be a little difficult but if you push on cartridge and push down on clip it should go back in... watch alignment of clip).

Then, check the pressure again. This should do it... note... I think they make a special puller kit or something for MOEN valves... I am not sure though as I have never used it... but if you do what I said you should not need it.

If this did not fix it... remove cartridge again and again confirm good pressure by pulsing lines... IF good pressure may need to replace the cartridge.

ALSO, note that if you do restore pressure to the valve... BUT hot and cold water are reversed, you will need to remove the cartridge and rotate it 180 degrees to fix!

Let me know if this helped by rating the answer. Thank you.

tait007
New Member Join Date: Jan 2008
Posts: 1
Is it possible that air in the line could blow the cartridge on a Moen single handle shower/tub faucet? Mine no longer works after having the water off in the house for a couple of hours. I have no pressure at all (small drips) when I turn the tap into the full position.
If you've had work done while the water was shut off then minerals built up in the pipe walls has broke loose and is now clogging the inlet ports of the cartridge. The solution is to shut the water off to the valve, open it up and pull the cartridge. Check and clean the inlet ports and before you button up turn the water back on to flush out the valve body and supplies. Good luck, Tom

Is it possible that air in the line could blow the cartridge on a Moen single handle shower/tub faucet? Mine no longer works after having the water off in the house for a couple of hours. I have no pressure at all (small drips) when I turn the tap into the full position.
Any tricks for getting the stem out? Seems nice and stuck in there. I'm scared to pull to hard with pliers for fear of pulling the pipes

I think you would be just fine giving it a good yank... but I also have heard of a pulling tool specifically for MOEN faucets... would need to talk to speedball1 or other plumber on this site to be sure as I as I am not.

BUT I still think a good yank will do it and should not hurt pipes IF you hold against the valve as you pull stem.