1 HANDLE TUB/SHOWER. WHEN YOU TURN THE SHOWER ON

remove and turn cartridge 180 degrees then re-install

Even if the cartridge looks good from the outside I have had them plug up internally with mineral deposits. I would remove cartridge and replace it.Hope this helps.Thank you

Sounds like the cause of your problem is the pressure balancing spool. Call Moen at
1-800-289-6636 and explain the problem. They will send a repair part to you free of charge. the link below is a "blow up" of your valve.

http://www.moen.com/shared/pdf/t3113pt.pdf

Hot on left.
Cold on right.
Some single handle faucets have bleed-over where both hot and cold enter mixing valve each time handle is turned on, even when faucet calls for just cold or just hot.
Otherwise maybe a do-it-yourself plumber got pipes backwards... or maybe the tub used to be on other side of wall, and tub was moved during remodeling but pipes were not changed.

To fix problem:
First of all, turn off shower faucet. Turn on Hot at sink and put ear against shower faucet listening for sound of water flowing through the mixing valve.
If mixing valve is working fine, you need to open wall and investigate more.
For example if you have access door, reach in and feel which pipe is hot.
Pipes might need to be reversed if problem comes up in home inspection, otherwise the problem will not harm anything.

these valves can be adjusted by removing the handle and adjusting the white gear that regulates the hot and cold that come out, try going more to one way if it gets colder then go the other way.

Can you remove handle , behind handle there should be a dial to move to increase hot or cold supply.

Remember where you start and remove it and replace a 1/8 to 1/4 turn counter clockwise, just put handle on try it and see if it changes and adjust accordingly.

Here is a quick check to see if the cartridge may be at fault allowing the cold and hot to mix. Turn off the hot water supply, with hot water supply off turn faucet on. Turn to the hot and cold sides, If you have only cold water then your faucet cartridge is at fault or the cartridge housing is worn. Shut all supply valves and remove cartridge and inspect housing for signs of wear. If wear is visible a new shower valve is needes. If none visible replace cartridge. I have included a link of a PDF file an exploded parts list. I hope this helps in solving your problem. Please rate if the answer helps in any way. Good Luck and have a great week. Jeff

adjust ur anti scold the setting is set to low when single handle shower units are shipped they are set in cold mode for safety ur install/instructional paperwork explains such and also advises on how to adjust---remove handle and on shaft will see a blue and red plastic clips that are adjustable slide towards u and move red for more hot water test water continue till comfort level is reached for hot water

Behind the handle there is a dial to adjust water temp cold and hot you can remove it and replace it a 1/4 turn til you can get both cold and hot. It is a anti scald it may have been put in wrong.

Make sure the cold water line is not blocked coming to valve and is open .

Hello, first if any water supply hot or cold is turned off, you will experience trickling as you mention. You must have both cold and hot in order to adjust the temperature on your valve. if you had a plumber intall this unit you should ask him to adjust it. Otherwise here is how:
Rotate the handle counterclockwise to stop and let water run till cold water is purged, check
temperature. Rotate handle to off, remove handle parts (see Disassembly in your manual) and temperature limit stop, rotate clockwise to decrease and counterclockwise to increase maximum hot water temperature, reinstall temperature limit stop and handle (TIP: Do not screw handle in until desired maximum temperature is achieved) Repeat steps until desired maximum
temperature is achieved