No cold water in shower even after cartridge replacement

Question

A couple weeks ago we realized that there is no cold water in one of our showers. When you turn the shower on, it is fully supplied with hot water. When you turn the handle all the way to the cold side, the water turns off.

Overall cold water supply to the house is fine, including cold water to the other fixtures in the same bathroom, the other bathroom, and the kitchen. So the problem seems to be localized to this specific shower. This morning I tried replacing the cartridge as that seemed the most likely problem, but the same thing is happening with the new cartridge, suggesting that the problem is upstream.

This is an American Standard single-handle faucet. The cartridge type is a 47mm 023529-0070A/H.

At the store, I also saw a pressure balancing unit which seems to be a more internal component, and wondered if that could be the problem, but wanted to ask for advice before taking more things apart...

Thanks!

Answer 1

I have encountered this problem with the culprit being either the pressure balance unit, ( usually incorporated into the cartridge)

Or a foreign body in the cold water line. ( found a screw lodged in the cold water inlet.)

Remove the cartridge and have someone turn the cold water on slowly to verify that you have water supplied to the cartridge.
If you do then the problem has to be in the cartridge/ balancer. The water out of the cartridge is mixed. ( if there is both cold and hot in.)

Answer 2

I had the same problem. I bought a new cartridge thinking that was it. I think my shower/bath faucet is a Delta 1600 or of the same design with the same parts. Replacing the cartridge did not help.

As a test I turned the cold water on with no cartridge and not a drop came out of the cold water inlet hole. The sink in the same bathroom worked fine. I figured something must have clogged the water line near the shower, or maybe the entire faucet assembly would have to be replace which would probably require removing tiles.

I learned about the pressure balancing spool (Moentrol valve). Apparently it can get corroded and then the piston can get pinned all the way to one side. I found the part on Amazon (I found at least two different styles so you have to make sure to get the correct part).

After I removed the old part I inspected it and noted that it requires quite a lot of work to remove or insert the piston inside of it due to corrosion (even after I tried cleaning it a bit by soaking in vinegar overnight). With the new part the piston inside will easily drop to the floor if you don't hold it in. When installing the new part I didn't do it right at first. I was worried about it being too tight, but I found I had to tighten it such that it "bottoms out" and the cap is flush against the housing.

Originally I was concerned about over tightening, but if you leave even a little gap the o-ring will escape under pressure. If that happens best to turn off the water again, remove, the part, reseat the o-ring, and do it again because if you try to tighten it after the o-ring "escapes" you will pinch the o-ring. Now about 24-hours and no drips, I kept the outer cover off so I could verify. Based on things I read I put a little silicone grease on each o-ring to try to make them last longer.

Maybe it's possible with some sanding or other measures I could have restored the old part, the key is that the piston has to be very free to move inside. Also, the five o-rings need to be in good shape (which mine were).

Also, I mentioned the piston can easily fall out if you tilt the new part, so be careful you don't accidently drop the piston behind the wall (luckily I didn't do that but I realized it could have easily happened when I was repeated removing the part due to not having it tight enough the first couple times because I did drop the piston into the bathtub each time). Also, make sure you have your drain plugged so you do not drop any screws down there.