No Heat from Dometic Cruisair 16K

[samoorelex]

Hi All,
I have a Cruisair 16K btu system on our sailboat that has been working for the past 5+ years. We used it intermittently. Now we are liveaboards.
We are in SC so it's not below freezing but when we turn on the heat "as of tonight" it's blowing cold air. Before we could feel warm air circulating throughout the boat from the air vents.
I can feel the water pump running. I'm seeing no errors. Where should I begin to diagnose the issue?
Brrrr.

Cheers and thanks for any input.

[BillKny]

We are in Charleston, SC, so I feel your pain... it's chilly...

With these units if you don't switch them back and forth between "heat" and "cool" occasionally the valve that does the reversing can get stuck, this is most likely what has happened to yours.

Try switching back and forth between heat and cool several times.

If that doesn't work, try tapping on the unit, gently at first, to see if you can free up the stuck valve. I don't know the 16K unit well, so can't tell you exactly where the valve is.

[samoorelex]

Thanks! - Will do.

[Coolerking]

What is the seawater temp there?
You feel the pump, but are you sure the water is flowing?
Check programming to ensure it is correct and will allow reverse cycle heat.
Check setpoint and temp as sensed by the system.
If all else fails, check for output voltage at the reversing valve outputs on the control board.
What is the exact model and thermostat type?

[samoorelex]

The water temp is about 50
I'll get more info tomorrow morning.
Thanks

[GreenWave]

There is a reset procedure that you can do. Unfortunately, I don't have it memorized and I am not near my boat at present. If you have the manual that should be there. Also make sure it is set to AUTO cycle betwen heat and cold. I literally just ran into this problem on one of mine a fewe weeks ago.

[Coolerking]

50 degree water will take time to generate heat, up
to 20 minutes, how long did you run it?
While the above advice regarding tapping on the valve assembly is correct, it rarely fixes it.
Be very careful and be sure you are tapping the correct part.
Checking all the other stuff I mentioned should be done before hitting it with a hammer.

[Dave22q]

Had same issue and finally replaced valve which worked for a month or so. eventually gave up and used a $50 space heater for the week or two Keys winter.

[Tracyandkimo]

just had the same issue w/0ne of the units on our boat. Even if the pump is running, make sure to look outside and confirm that there is water being discharged. Our coil had frozen. Fortunately, it didn't rupture. I think our problem originated due to lack of airflow where the unit was housed beneath the master birth where we had a foot of blankets draped down the the floor.
And, as others had mentioned, the reversal valve may be stuck.

[rhirwin]

Sea temp makes a huge difference in heat output. At 50F sea temp you are right at the limits of heat output for your Cruisair Dometic. I have the same unit. One trick the distributor showed me for the heat cycle was at the start to manually put the fan on the lowest speed for 5-10 min. Unclear the physics of why this works but in marginal conditions it can work. BTW, I installed an Eperspacher diesel heater for such conditions its great and I use the fan mode from the Cruisair to help circulation

[samoorelex]

Here are a couple of tidbits so far.
The unit is a 16k Dometic Turbo(STX16-410a). It's about 6YO.
I have an SMX II controller.
We've figured out how to set it to auto. Press heat and cool simultaneously.
Good learning.
We've been lightly tapping on the solenoid valve... see picture.
We can hear something clicking as we adjust the temp from 62-85 for testing.
We'll leave it at 85 for a bit to see it if heats up. I had not anticipated the time it takes to get up to heating. I didn't recall it taking that long.
Thanks for all the help.

If the picture doesn't come up here is a link to the file.
https://drive.google.com/file/d/1oJf...ew?usp=sharing

[garychurch]

If you don’t have an error “Service” light on the master control you may have a stuck reversing valve that’s controlled by a solenoid value on the chiller.

As mentioned you may want to tap on the solenoid to see if you can unstick the reversing value.

It is recommended you occasionally change from heat to cold to ensure the reversing value doesn’t get stuck in either heat or cold positions.

If you have an air handler there is a bypass value activated by the temperature control on each unit that either circulates hot or cold water. If this value is not working you can circulate hot water but it can bypass the air handler. At least this value can be manually manipulated to ensure circulation through the air handler.

I apologize I am not familiar with you unit, so these suggestion may not apply.

[Tin Tin]

Our reversing solenoid failed, gave all the same symptons. Replacement of solenoid is easy enough and not very expensive, can buy on-line, it should have the part number on it.

[Coolerking]

If the coil is bad, that's easy, but, you need to confirm with a meter that the coil is being energized by the system calling for heat.
If the valve assembly is hung up, that's a huge repair, especially on that unit which is very compact.
Both parts would need to be purchased from the mfg as they are oem.

[samoorelex]

More info.
We have plenty of water pumping in both hot and cold.
We switched to cool and set the temp to 61F. The air coming through the vent was not cold. It's circulating the interior air and not cooling it either.
I'm not sure on how to remove the solenoid and how to test it.
I'm guessing that is the problem. We are hearing 2-3 clicks when we turn the unit to cool or switch from cool to heat. I would have thought we might see some magnetic pull from the solenoid when activated. I didn't detect any.
I saw from one of the comments that changing the solenoid should be easy.
Thoughts?

Thanks!