If you are getting no flow after the pump this will cause high pressure you could ohm out the windings but if its original I'd just replace it if the motor won't run that is a start run capacitor that could be the problem it should have a uf rating on it they are less costly then the pump some times the capacitor will bulge if its no good. Pump won't run if star capacitor is no good.

 

I posted answer to a fresh water pump issue instead of AC pump issues. :smt021

 

Bypass the pressure switch if it won't start. If it starts, you will need a new switch.

Is there a pressure switch on the A/C pump?

 

Looking at the pick there is just the line voltage and start run capacitor no flow switch the pressure error was from the refrigerant side of the a/c I believe due to no water flow causing high head pressure

 

it could be the trigger switch in the control panel. to test put a plug on the wires and plug it into a receptacle.

 

Line dirty from the pump through the A/C unit?

 

Get a multimeter with ohms reading and test the leads. If any go to ground, it is likely a bad motor. If all have resistance, then also check the capacitor to make sure it hits the right uF ratings.

 

good question. I didn't check that. I just assumed that since the motor was completely silent that it was either a dead motor or the motor not getting a signal to run (electrical). In my experience, usually the motor will at least humm if it is trying to work through a clog. I'll check the lines though - easy enough. Thx

 

will try that. Thx

 

Thx gerryb. I didn't have an tester with me, but you suggestion is first on my list when I return to the boat. Thx.

 

I would replace the pump with a new water cooled totally in-closed unit, your current unit is not worth repairing you want reliability

 

great suggestion. Can you point me to it? I assume it only needs be 115v, minimally capable of the same flow (approx 1000 gph), and compatible with the input/output connections.

 

Is your boat having a mutiny? First its the head, next its the AC. lol...

Should be easy to test byconnecting the motor to an AC cord, and then hooking up a hose to the inlet with the other end in a bucket of water?

 

Too hot out to cheap out on a new pump. Don't overthink it. Hook up power to it, evaluate, have a sip of rum, bite the bullet, buy a new pump, move on and enjoy the rest of your boating season.

 

I agree electricaldoctor! Looking for the replacement unit now.

 

thanks skibum - I was so convinced it was the motor.... I just bench-tested it and it's NOT the motor. Something else is causing the motor not to kick-in. ideas?

 

Great news that your AC pump motor is operational. My AC pump has a separate breaker and it runs all of the time whether both of the AC units are working or not. There is obviously something wrong with my control box, but that is not a deal breaker at this point in time. Have you checked to see that you have the proper voltage leaving your breaker? You can have a bad breaker. If your breaker checks out okay, take the previous advice and follow that wire from the breaker to determine where it terminates and go from there. The follow the wire from the AC pump back to where it terminates. In both cases, these wires should terminate in a control box of one type or another.

 

I had a high pressure error on mine once while sitting at the dock. My Dometic manual said that the high pressure warning could happen if there was a lack of water flow. I took the water hose from the dock and stuck it in the hole that the water from the AC comes out of, and filled it up. It started working fine after that, and I have never seen the problem again. Not sure if it will fix your issue, but there might be some crud in the lines after the pump that you can clear out with the back pressure. Worth a try for a $0 fix...

 

I'll could try that. But that doesn't explain the motor not kicking in when. the AC units blow but the motor doesn't kick so it gets no water and signals the high pressure reading. maybe a breaker somewhere or the actual controller not sending a signal to the motor?

 

No, it doesn't. When it happened to me, I opened the ER hatch and didn't hear the motor running either.

There should be a relay somewhere that uses the DC signal from the control panel to turn on the AC circuit to the motor. The motor works, so I would follow the AC power lines from it. I suspect that you will find a relay, or an SCR (silicion controlled rectifier - fancy name for a digital relay). Once you find the relay, turn the system on and try to measure the DC voltage on the control side of it. The panel should send either 5v or 12v to it. If you see the voltage on that side, but the motor still doesn't run, the relay might be toast.

 

I know that this is not helping "gspaid" but my 1988 390 EC has the original "3-knobber" controls on both units and the AC pump may have worked as you described when new. I do believe that the control box is defective on mine because the pump runs 24/7. We have 2 water exits on the port side.

 

When you say the motor runs are you sure that it also pumps water? Because if the impeller in the pump is bad the motor would run, but not pump enough water to cool the A/C unit. You need to hook up the pump to a bucket of water and make sure it pumps. If it is a 985 gallon per hour pump, it should drain a 5 gallon pail in about 20 seconds.

According to the cruiseair manual, the schematics for the unit are in the units electrical box and there is a pump relay with it's own 20 amp breaker. I snipped this from the manual which I down loaded from the Searay website for my 400 DA. yours might be slightly different.

Electrical
• The wiring diagram is located in the electrical box. If that diagram is damaged or if you need a copy, please call Dometic with the unit part number, serial number, and wiring diagram number, all of which are located on the unit data plate.
• All butt connections on pumps wire tightly crimped and heat shrunk
• AC power source installed and grounded/bonded in accordance with ABYC standards
• Control wires connected to terminal strip with captive fork or ring terminals
• Circuit breakers sized according to specifications on the data plate label
• Digital display cable is connected at both ends
• Pump Relay Panel (if used) has a dedicated circuit breaker sized for the pump but not to exceed 20 amps maximum

Hope this helps,

Pete

 

The same thing was happening to my a/c units. I replaced the 1 hp motor unit with a 1.5 unit. Water flow was much improved; however, this did not completely solve my flow problem which was triggering the high pressure turn off switch. Had to flush the raw water cooling system with acid. My A/C service guy dose this. There is a do it yourself way I have started doing. Take the line off from the strainer to the pump; hook up a water hose fitting and attach a water hose. On the other end hook up a pump that is drawing from a bucket/container of muriatic acid. (There is a way to hook up a simple acid flush devise using standard PVC fittings and a water hose. Look at some whole sale a/c supply stores and they will be listed for such devices. I made my own from all of $25.) Pump the acid in the system until it just starts coming out through the out flow vets. Let it sit for 3 to 5 minutes; then flush with clean water. Repeat; I do this until there is just clean fluid coming through the out over boards. I am in salt water and calcium build up is an ever present problem. I do this procedure several times a year. There is no damage to the plastic pump or the a/c condensers.

 

thanks Pete. The motor and pump housing are fine and it pumps water. I will definitely look for a circuit breaker in the system, but though that the A/C Pump Relay switch on the control panel acted as the circuit breaker.

I plan to go do some more on-site troubleshooting next week and will post the results. My fingers are crossed that it's something simple like a overlooked breaker.

 

So I'm at the boat: The water pump is fine. the problem is the signal from the Salon AC unit TO the pump. The forward cabin AC works like a champ - when it kicks in, it sends a signal to the pump and the pump purrs like a kitten. In fact, as long as the forward cabin AC is running (making the water pump supply water to both AC units) the Salon unit runs fine too. However, when the Salon AC tries to run by it's self, it doesn't send a signal to the water pump. Any thoughts or advice before I take the covers off the Salon AC electrical to see what might be happening?

 

Check this sight out too

http://www.cruisersforum.com/forums/f115/how-to-flush-a-c-cooling-water-40396.html