Why does moentrol bath valve give hot water pointed to "C" and vice versa?

A bit more information is needed; is this a Moentrol or a Posi-temp valve? You will need to shut water down to the shower. If it is a Moentrol, it could be an issue with either the cartridge or the pressure balancing spool. If you are at least getting water, I am going to assume that it is a Moentrol.
You will need to turn water off to the valve. Pull the cartridge and examine as to whether or not debris is blocking the supply holes of the cartridge. If your valve has built in shut off screws, you can slowly turn water on to clear any debris that may be inside the inlet port. I typically use a piece of PVC to go over the valve body so that water does not leak between the wall and the shower. Again, just turn water on enough to start it flowing.
If you do not notice anything amiss with the cartridge, it could also be the pressure balancing spool. If that is on your valve, it will be a flat head screw about the size of a nickel. Water will need to be off for the removal of the spool as well. Again, you will be looking for debris that is blocking water flow.
If this is an older Moen faucet, you may just want to replace the cartridge while you have it removed. If it is a push/pull, it is a Moentrol. If you have to turn the handle for water to come out, it is a Posi-temp. In my area, the cartridges run from $20-$40. However, Moen does offer lifetime on their cartridges. Lately, I have had a few more hoops to jump through to get the replacement cartridges from Moen, but they are still very pleasant to deal with.

You should be able to find a manual on Moen's website if you have the model number for the valve. www.moen.com.


Regards,

DIYpro

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

Assuming that you have hot water at other faucets the problem could be a varnish buildup in the cartridge. After shutting off the hot and cold water either by turning off the main or at the faucet stops (if equipped), remove the cartridge and soak it in white vinegar to break up the varnish. You can clean it up with an old toothbrush and make sure that it is working. It should rattle when you shake it. new cartridges are not very expensive so you can just buy a replacement at any home center as well. If you are the original owner of the faucet Moen will send you a free replacement cartridge if you call them.

You have water going to it just like a regular valve, but you run the water out of the 3 function piece to your different water features.

Balancing spool is froze up. If it is a moentrol valve then it has a separate spool that can be removed and replaced. Sometimes you can take it out and get it to break loose and working again by tapping it on a hard surface a few times. If not then it needs replaced.
If it is a positemp valve the spool is built into the cartridge and it will need to be replaced.

there is a clip holding the cartridge in place. You need to remove that and then there is a little plastic throw away tool that comes with a new cartridge that you use to break the seals loose on the old cartridge....then you use a pair of channel locks to grab the stem and pull it out. The new cartridge should come with detailed instructions.
If it is a moentrol valve...the part number is 1225 and if it is a posi-temp it is a 1222. Moentrol you pull out to turn on and then left and right for temp adjustment. Posi-temp just turns to turn on and you turn from cold to hot to adjust through the temp range.

Did you change the cartridge? Only use a genuine Moen 1225B cartridge the off brands do not last call Moen they will send you a new one for free

Something is caught in the stem. Make sure the stem is free of debris. Also check that the valve or cartridge is intact.

http://www.moen.com/contact.cfm?location=TopNavCustomerSupport

You will find a quicker answer and free parts for your bath room faucet at link above . I am sure it is the mixer valve assembly. If you are not a plumber I suggest a pro be called.

John