Cruisair AC Relay 1989 300

K

Karen S Little

New Member
Jan 9, 2021
28
Boat Info
1989 SR 300 Sundancer
Engines
twin Mercruiser 5.7
Hi Hope this is the correct thread. We have a 1989 300 Weekender with the original Cruisair 10000 BTU AC system (three knob control panel).

I flushed the system with Barnacle Buster and replaced the wet section of the circ pump. I did not re-prime the pump prior to turning it on (I know - I calling myself the same names), and it ran - with a loud noise - four times I switched it on and off, until the unit will not start at all now. I've done enough research to know there could be a fuse (not normally on a single system installation), possibly a open no flow relay, or a open pressure switch relay.

My question is, are these relays re-setable - can I reset them (after re-priming of course) . Thanks for any help
 
Last edited:
The pump won’t run or the ac unit? You don’t need to prime the pump. The high pressure cutout will reset by itself when ac unit cools down. There is not a fuse but should be breaker in main panel.
 
Agree, what pump won’t work? Are we talking the Mach pump that draws water from the strainer or the AC’s circulation pump that moves Freon?
 
Mark.60 said:
The pump won’t run or the ac unit? You don’t need to prime the pump. The high pressure cutout will reset by itself when ac unit cools down. There is not a fuse but should be breaker in main panel.
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thanks Mark the system did reset - next to prime the pump correctly
 
dwna1a said:
Agree, what pump won’t work? Are we talking the Mach pump that draws water from the strainer or the AC’s circulation pump that moves Freon?
Click to expand...
The March water circ pump after the strainer
 
You don’t have to prime the pump, make sure the thru hull valve is opened and the hydraulic pressure is all you need.wish i needed ac as the outside temp is about 30.Hope it works
 
Strange, Unless I loosen them on the outlet side of the march pump she is no seawater to either AC
 
The March pump has a magnetic drive , if there is a restriction inlet or discharge side the pump will decouple from the motor. The motor will run but the pump will not spin, I have seen more than one pump be replaced when it wasn’t the problem. You can put a garden hose in the hose going to ac unit to check for good flow. Hope this is helpful
 
Ok Karen if you are in a warm environment go to the discharge outlet on the outer hull of your boat, put a garden hose to it and push the water into the system, all while the pump is on. See if it will prime. Another trick is to use a wet/dry vac and draw the water thru the system. If you can take the boat out on the water then cut the system on and run the boat thru the water, it will displace the air. Make sure the strainer is clean and the seacock is open

let us know how it goes
 
Mark.60 said:
The March pump has a magnetic drive , if there is a restriction inlet or discharge side the pump will decouple from the motor. The motor will run but the pump will not spin, I have seen more than one pump be replaced when it wasn’t the problem. You can put a garden hose in the hose going to ac unit to check for good flow. Hope this is helpful
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will try this. after i primed it yesterday, there is a small amount of water exiting the overboard discharge but it is tiny and sometimes stops.
 
Karen sometimes it takes a bit more than once or just a few minutes. Remember that these pumps do not move air. Also be sure the seacock is open and the strainer basket is clean.

Always start with the simple stuff. Start at the strainer, then the pump, and then to the unit.

I do have SOME of the parts at the AC. Keep us informed please
 
Karen,try to flush the line from the strainer back through the ball valve and out the bottom of the boat. Use a hose and let it flow hard. Better than a haul out. Don’t be concerned about air in the line, just no leaks. Keep me posted
 
Thanks everyone. Update:
Seacock - open
Strainer - clean

I did have some water coming out the hull exit (about a pencil width/no where near 5gpm) but it stopped after about 35 minutes.

I did try and prime again today - I am priming from the hose that attaches to the AC Inlet pipe. Ive dumped a little more than quart into that 5/8 inch hose - reattached the hose and turned on the circ pump. Nothing

I checked the strainer again - clear

The circ pump does run. at least the elec side

I have not yet tried the previous idea of garden hose or wet/dry vac. will do that tomorrow

Is it possible the 5/8 inch line from circ pump to AC has a split and is leaking water?
 
If you had a split in the hose you would see lots of water in the bilge, could be a bad pump. On last thing is to take hose from discharge side of pump. Attach hose from discharge side to a bucket and make sure pump is moving enough water
 
Karen we take the garden hose with the nozzle on it. Pressurize the system from the discharge on the side of the boat, wait for a minute while the air is forced out, and have somebody cut the pump on. You are basically back flushing the system until you cut the pump on. IF it does not prime it’s the pump.
 
Mark.60 said:
If you had a split in the hose you would see lots of water in the bilge, could be a bad pump. On last thing is to take hose from discharge side of pump. Attach hose from discharge side to a bucket and make sure pump is moving enough water
Click to expand...
 
thanks everyone. i tried the back pressure method and the best I could get was a pencil size stream of water at the discharge point. i replaced the pump, primed, and now have full water discharge (garden hose in size) at the exit point. Appreciate everyone's advice and time.

If it is not too much trouble, and if you have the same Cruisair 10000 BTU system, could I trouble you for a jpg of the temp control switch from the back side. I am trying to ensure I have each wire connected at the correct point. Again, thanks so much.
 
Karen S Little said:
thanks everyone. i tried the back pressure method and the best I could get was a pencil size stream of water at the discharge point. i replaced the pump, primed, and now have full water discharge (garden hose in size) at the exit point. Appreciate everyone's advice and time.

If it is not too much trouble, and if you have the same Cruisair 10000 BTU system, could I trouble you for a jpg of the temp control switch from the back side. I am trying to ensure I have each wire connected at the correct point. Again, thanks so much.
Click to expand...

Wiring diagrams start on page 25.

https://www.dometic.com/assets/27/52/installation and operating manual_62752.pdf
 
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