Air Conditioning Circulation Pumps Problem

[RedSunByNight]

Hi, my husband and I bought a 1988 65MY extended to 73’ CPMY with twin 2010 Series 60 MTU’s. We liveaboard and love the vessel! Many updates completed, but issue Friday with AC circulation pumps caught us off-guard. Two Oberdorfer 104M-06 pumps positioned together under port side floor of engine room (which was made one room by prev owner) fwd of port eng. Pump #2 apparently developed a pin-sized hole thru front bronze plate, getting it and the other pump wet and throwing both breakers in panel #1 and #2 respectively, pump smoked and smelled burnt. So, we bought two new 104M-06 pumps yesterday and installed one late last night trying to get some air conditioning going in some of vessel at least. Pumps are 110/230 capable. Connected wiring following the diagram for 110v and hoses. Opened seacocks and flipped the breaker….and NOTHING!! Each pump is connected to its own ac manifold supplying both split and self-contained unit governed with a dedicated Cruisair ac switch. Any ideas on what is the problem? Could there be a fuse between the pump and the breaker panel? Could the two pumps be connected via the switches such that both have to be connected for either to work? Any guidance is really appreciated. Thanks very much. Sherry and Matt L.

[Captain Ralph]

There is a pump relay board between the ckt breaker and the pump motor. This controller receives a signal from the cabin AC unit and turns the pump on. This way, the pump does not run till at least one (any one) AC unit is turned on.
I am sure you tried to turn a few cabin AC units on.

This controller is usually in the gen-set room, after port bulkhead past the last A/C condensing station.

My comments next will have somebody working with a volt meter reaching towards live electricity. If you are not comfortable working with electricity, please find an electrician.


You may have two of these boxes. One from each of the ckt breakers.
Remove the cover to these approx 8" x 10" boxes, under the cover should be a schematic helping you identify the wire terminal connects. For example, the electric wires from the ckt breaker may go to the top right 2 terminal screws. This schematic will also show the connects providing electricity (when turned on) to the pump.
With a volt meter, verify 120Vac at the input terminals, if good, turn a cabin AC unit on and verify 120Vac out to the pump.
Here is where I fear your problem is. No voltage out to the pump.

If there is not any ACV out to the pump, Post a picture of the controller showing the connects, board and anything else in there.
Some of these are repairable (most are not).
We may be able to jump the wires to make the pump constantly run and offer some temporary relief.

[RedSunByNight]

There is a pump relay board between the ckt breaker and the pump motor. This controller receives a signal from the cabin AC unit and turns the pump on. This way, the pump does not run till at least one (any one) AC unit is turned on.
I am sure you tried to turn a few cabin AC units on.

This controller is usually in the gen-set room, after port bulkhead past the last A/C condensing station.

My comments next will have somebody working with a volt meter reaching towards live electricity. If you are not comfortable working with electricity, please find an electrician.


You may have two of these boxes. One from each of the ckt breakers.
Remove the cover to these 8" x 10" boxes, under the cover should be a schematic helping you identify the wire terminal connects. For example, the electric wires from the ckt breaker may go to the top right 2 terminal screws. This schematic will also show the connects to out put to the pump.
With a volt meter, verify ACv at the input terminals, if good, turn a cabin AC unit on and verify ACv out to the pump.
Here is where I fear your problem is. No voltage uot to the pump.

Thank you Captain Ralph! We will check as you suggest now! Really appreciate your help.

[firbanks]

Our 1988 67CMY (60’ MY with a factory cockpit) has the pumps in the same spot so I assume that would be factory. The pumps need to have one of the AC units that feed the cruiseair box to be in cooling mode and calling for cooling in order to turn the pump on. The key is that the unit can’t have any faults or it won’t call for cooling. Did you turn the controls to “off” then to “cool” mode to clear the “hi ps” fault that would have resulted from low seawater cooling flow? I don’t know of a separate fuse or thermal overload between the breaker and the pump motor (but it may have one!) but frying the motor could have also burned the relay that calls for cooling in the box. The previous owner to our boat installed what the ac guy called “bimini switches” that are toggle switches on the bottom of the relay box that bypass the relay and allow for direct powering the pump. This supports either troubleshooting or to bypass the relays when you just want to sleep through the night and not do ac maintenance (or when in “bimini” and parts and labor are in short supply!). I have a couple of pump trigger relays as spares - I’ve had good luck with Microair - something similar to this:https://www.microair.net/collections...-and-tr230Good luck!

[firbanks]

https://www.microair.net/collections...r115-and-tr230

[RedSunByNight]

Thank you firbanks on all. We are heading to generator room armed with info from Captain Ralph and you….. and come to think of it I found a spare ac switch relay trigger down there a while back…. Sounds like it may come in handy….will report back!

[Captain Ralph]

Luv to read good news.
Also glad you found a tech to help quickly.
All safe, cool and you don't have new curly hair..

[Bob Quinn]

I'm curious, do you know how they tested water flow?

[Pascal]

Speaking of flow measuring… has anyone ever fitted flow meters to an air con system? I ve often wished I could easily see the flow to each chiller (or remote condenser) to catch any issue before it eventually trips an HIPS error

After all, water makers have flow meters, why not air con ?

[Captain Ralph]

I'm curious, do you know how they tested water flow?

After cleaning my strainers, I watch the discharge. Usually 10 inches from the hull when it hits the water.
Now, Hatt vs Bertram.
For some reason, Hatteras keeps the AC water discharge at the water line.
FM, how do you know if it is flowing well?