Strange Shower Issue

[bmidlam]

We are preparing to leave on a 2 month trip in the middle of August and our new-to-us Flying Cloud 30FBB is having a shower issue. The hot water works in the sinks but in the shower it goes from cold tap water to room temperature at best. I'm okay with it but the kids aren't overly thrilled. If a sink is turned on to hot while the shower is in use it goes from room temp to cold immediately. I have also noticed that the bathroom sink doesn't get that hot when the kitchen sink is also on hot.

A few things to note:

• I have tried it on electric, propane and with both turned to on and nothing changes. The light does not indicate any issue with the heater firing.
• I have checked the bypass valve and it's set to on not winterized (obviously since sinks get hot water)
• I have played with the water pressure coming into the AS to try to see if that helps but no change
• We do have a Clear Source set up but we tried it without the filtration system and nothing changed.

My last plan is to fill the fresh water tank and turn on the pump to see if it works that way but otherwise I'm out of ideas and not that handy with plumbing. Also, most service departments are so backed up we can't get an appointment before we leave. Any suggestions would be so greatly appreciated!

[GetawA-S]

It sounds like the mixer valve for your shower needs adjustment. Find out the A-S part number and manufacturer/model, and download the manual from the internet. Chances are it is accessible from a wall panel held on by four screws.
No shame in calling a plumber.
Good luck!

[bmidlam]

Thanks I will try this next!

[CMHM]

This happened to us when camping in winter, when it is freezing outside the water gets heated on the opposite side of the Airstream and then travels all the way to the shower (see pipe diagrams to see the long distance) and it cools down. Not sure if this applies to you because its summer right now.

[Mollysdad]

Is it possible the shower fixture itself is not allowing the hot water through?
Some handles have a cartridge to replace.
There might also be a device to maintain a certain temp which is not functioning.
Mine looks like this and I have to crank it about 190 degrees for a hot shower.
Might be worth a peek inside.

[sheriff1]

Make sure the outside shower valves are off. If they are on and the shutoff in the handle is closed you will get some strangeness.

[Gene]

There may not be enough pressure to feed more than one faucet with hot water. If at a campground with low pressure, or medium pressure plus a pressure regulator, pressure can be low. Some recent models, I think, have an internal pressure regulator, so checking whether you have that and whether it is lowering pressure too much, may be one way to go.

The mixing valve may also be the problem. I found that the one in our 2008, after I had shut off the water to soap up and conserve hot water, would send out cold water for about 15-20 seconds (seems longer when it hits you) before I got hot water again. I learned to direct the shower away from me for that period. It could also be a bad cartridge on the mixing valve. Some mixing valves may have adjustments. And it could be a blockage in the hot water line to the shower. We have an external filter for city water because you never can be sure what campgrounds have and we have known people who got giardia. You need a 5 micron filter to remove giardia. It can also prevent blockages in the lines.