Full pressure, no hot water in shower

[ucsbgaucho]

We have a guest bathroom shower that we hardly use, probably once since a year ago. A month or so ago, guests tried to use it and found the water when turned to hot would trickle out, cold was full pressure. Sink in the same bathroom has no problems. My father-in-law came to look at it, opened up the knob (I believe a Moen single-arm valve) and was able to get full pressure coming out of both the hot and cold sides, but still no hot water. Is there any suggestions? We have guests coming tomorrow, and while we have an additional guest shower downstairs they can use, we'd love to get this one working!

 

[johnjh2o]

What you have is a Moen posi temp valve. You need to replace the stem. If there not used for a long time the balancing spool becomes frozen. If you call Moen's 800# they will send you a new stem free of charge.

John

 

[IFIXH20]

A small tip I give my customers to help prevent problems like yours. I recommend
running water at all fixtures that are not used regularly every two weeks, this keep
your plumbing lube and in working order , it also replenish your traps.