AC Motor going

[timjet]

I was out on the boat this week and tried to turn on the AC and the water pump didn't work. I took a screwdriver and turned the motor armature by moving the cooling fan blade and it worked, but this motor is probably on it's last legs being 12 years old and being on a FL boat all it's life. The motor is connected to the water pump which looks OK. The pump has a name plate listing FASCO as the manufacturer but no model number. It does have a serial number.*Anyone know where to get a replacement motor? I would think the pump would be OK.
Thanks guys.


Tim

 

[bluebyu]

http://www.fasco.com/index.htm

http://www.fasco.com/DistLocDetail.asp?opt=1

Grainger carries also carries some Fasco motors

-- Edited by bluebyu on Saturday 4th of September 2010 05:36:51 PM

 

[FF]

Three & One oil might get another decade or two.

 

[timjet]

Thanks guys. Lots of distributors near me, so I should be able to get a replacement. Since there is no model number I guess I'll have to take the unit in and see if they can get a close match.
FF, I'll oil it as you mentioned and keep it as a spare.

-- Edited by timjet on Sunday 5th of September 2010 07:50:20 AM

 

[Larry M]

We just bought a spare for our 2-16,000 BTU units.* We run one pump for both.* It's a March-AC-5CP-MD 1080GPH pump.* We bought it on EBay for about half of what*the local AC guy wanted.

For more pump information take a look at: *http://www.depcopump.com/catalogs.htm*

Larry/Lena
Hobo KK42
La Paz, BCS, MX

 

[sunchaser]

The motor may be going because the pump is gunked up or BO. You may want to consider changing out both at same time.

 

[Roostor]

...Might want to try cleaning your system first..may have some blockage from marine growth. I had some issues with my a/c; had the system flushed with "Barnicle Buster" and now all is fine. just my $.02.

 

[timjet]

Larry,
That is the exact same pump that I have. Depco located only about an hours drive from me sells the pump for about $100 more than e-bay.
Thanks

 

[timjet]

FF wrote:

Three & One oil might get another decade or two.

Don't know if I can get a decade or two, but I did oil it and will put it back on the boat. I've got some engine issues that is costing me plenty, so I'm going to wait on the replacement.

 

[timjet]

Ok guys, I can't figure this out. My air conditioning pump/motor finally quit this last weekend. It hasn't started on it's own for a couple of weeks and I could get it started by using a screwdriver and moving the fan blades in the motor. Last weekend that wouldn't work.
So I brought the motor/pump home it's a March-AC-5CP-MD 1080GPH pump, installed a plug on the wires and plugged it in. Works every time.

What am I missing. Is there some sort of control circuit on the Air conditioning system that perhaps has failed. What happens is, I turn on the air conditioning system, it takes about 15 seconds and the blower and pump then turn on. Now after 15 seconds the blower comes on but no pump and about 10 seconds after that it pops the breaker.

What gives??

 

[Shoalwaters]

Tim, this sounds similar to my Cruisair setup. An a/c unit decides it needs cooling water and sends a signal to a trigger (solid state relay) in a box near the pump. The trigger in turn sends a signal to a heavier relay which handles the pump current and turns the pump on. Several a/c units can communicate with the pump in this way. I suspect one of your triggers is faulty. Thus when the a/c unit needs cooling water, doesn't get it and trips a breaker or its own thermal protection.

I had a similar problem with one of my a/c's. I condemned the trigger/relay box and connected the pump directly to it's breaker. The pump now runs whenever the breaker is switched on, regardless of whether any of the a/c's are running. One less thing to go wrong and it let's me run the pump without involving the a/c's. Handy for burping the system after cleaning the strainer.

Edit: Hmmm, after reading your post again, I'm not sure your problem is the triggers after all. However, if you bypass them, you will be able to eliminate them from the list of suspects!

-- Edited by Shoalwaters on Monday 4th of October 2010 04:20:21 PM

 

[Keith]

You need to hook up a voltmeter with the pump installed on the boat to see if it's being energized, but not turning. It it's getting the voltage but not running, it's bad. If it's not getting the voltage, it's the relay system upstream. Probably the pump though.

 

[Phil Fill]

I would take the motor in and have it repaired/rewired. But I am cheap!* *We have 60 year old electric motors in our plant, some are not made or replacable anymore so we take to a local motor repair shop.

The amount of time you putz with it, you could have pulled it, had it repair and back in by now!

 

[RickB]

timjet wrote:
What am I missing. Is there some sort of control circuit on the Air conditioning system that perhaps has failed. What happens is, I turn on the air conditioning system, it takes about 15 seconds and the blower and pump then turn on. Now after 15 seconds the blower comes on but no pump and about 10 seconds after that it pops the breaker.

That motor is a capacitor start (or run) and most likely has a start winding and switch. Since it is a magnetic drive unit, even if the impeller was locked tight it would not prevent the motor from starting and running.

It is likely that one of two things have gone wrong. The capacitor has failed, or the internal centrifugal start switch is failing or has failed. The switch is mounted on the end bell and is operted by a flyweight that opens the starting winding ciruit when the motor is up to speed. If the switch does not close or has corrosion on the contacts it will create an overload on the motor, prevent it from starting, *and the thermal cutout will then open and you have a temporarily dead motor.

It would start when you flipped the armature by hand because that got the thing moving, which is the role of the start winding. It probably worked fine at home because the voltage was higher, the movement from removing it made the switch contact, or a combination of the two.

You might want to test the circuit before spending money on a new pump. That unit should draw about 2 ams, take a clamp meter and see what you get when it tries to start. Disconnect the motor and replace it with a 250 watt light bulb and see if the system works OK otherwise.

It is hardly worth rewinding the thing, few motors are these days except for large multi HP industrial units. If you are handy at all you can look at the start switch and test the capacitor before giving up on it. Start switches are easy to replace and inexpensive as are capacitors.

 

[timjet]

The unit I have is a Marine Air, 12000 and 16000 BTU units. There is one pump which has its own CB along with a CB for the 12K unit and one CB for the 16K unit. These 3 CB's make up one of the two alternating current circuits on the boat, it is 30 amp. The other 30 amp AC circuit runs everything else which has AC on the boat.
My current location has only 15 amp service so I can run only one air conditioning unit at a time, unless I run the genset. I have been at this location since May and it has worked OK until recently.

The pump is plumbed so that when on, water is pumped to both units regardless of which one is on. I talked to the Marine Air people and the tech said that my unit has a history of failure. The part prone to failure is a circuit board with the pump start relay on it. He suggested like you guys have mentioned, to check voltage at the pump when I turn the unit on. If no or low voltage he suggested replacing the board with the pump start relay on it.

However, I thought that like Mike mentioned to simply rewire the pump directly to the pump CB by-passing the pump start relay. I would have to manually turn on the CB when I use either air conditioning unit, but I have to anyway with the current setup.

Like Rick mentioned the start capacitor may be weak and that is easy to replace, as long as one can be found, shouldn't be too difficult. It definitely has a start capacitor. So far I'm inclined to believe the pump is OK and the fault is in the pump start relay circuit board for two reason. The tech mentioned this part has a history of early failure and as I mentioned, when I try it at home, the pump works fine. Incidentally Rick, when I run the pump at home the motor runs fine and I can see the pump impeller turning. As far as the internal centrifugal start switch, I didn't know a small motor like this would have one, the start capacitor taking its place.

What I will do is check to see if I'm getting the same voltage at the pump that shows on the AC meter on the boat. If it is low or 0, I'll rewire the pump directly to the pump CB. Hopefully this is the problem, for I think the pump start circuit board will cost more than the pump itself. Of course wiring the pump directly to the CB may be more difficult than I envision.
Thanks Guys.




-- Edited by timjet on Tuesday 5th of October 2010 08:01:37 PM

-- Edited by timjet on Tuesday 5th of October 2010 08:03:20 PM

 

[C lectric]

I don't know your ac unit but.

What you posted last sounds reasonable when you say there are three C.B.s, one specifically for the pump, and you included what the service guy said and the motor works fine at home. Before you do a work around ask what a new board or a reconditioned one, if available will cost.

How comfortable are you with wiring? You could get a replacement board mount relay and replace the burned one if that is what it turns out to be. Folks like Digikey and Newark electronics can offer an amazing supply of these things. You may find if you check the board that there is a mfgr name and model/part # on the relay.

Either way, if you repair or purchase a board, then I would suggest that the new board mount relay then be used to drive a small CONTACTOR/STARTER with a 120V coil and a SNUBBER which will protect the board mount relay. The board mount relay will no longer directly control the motor. The Contactor will then be controlled by the board mount relay*which is much , much heavier and able to withstand the motor current and backflash from the motor upon disconnect.

Anyway, just a thought.

-- Edited by C lectric on Wednesday 6th of October 2010 06:46:49 PM

 

[timjet]

Well I just got back from the boat and put a multi tester on the motor leads. I'm showing 120 volts when the pump CB is on. This seems strange because before when it was working properly there was a delay of about 10 sec from when the CB was on and when the motor would start.
So, I'm now thinking that maybe the start capacitor is at fault. The dock service is only 15 amp and am thinking that maybe there is just not enough amps to start the motor if the start capacitor is weak.
In looking at the circuit board, it would be easy enough to install a jumper from the power in terminal of the board to the motor output terminal, but as I said above that may not be the problem.
Any Idea what a start capacitor for a small motor like this costs and where to get one?
I'm generally against just replacing stuff and see if it works, but in this case that may be the direction to go, if the capacitor is cheap.

-- Edited by timjet on Thursday 7th of October 2010 08:37:34 PM

 

[markpierce]

Fortunately, I live in an area where mechanical air-cooling on a boat is economically unjustifiable.* (The cost doesn't justify the impulse to have it.)

 

[C lectric]

The capacitors are cheap compared to as you say just replacing stuff. I'll guess $10.00

Take the old one to a motor shop and they can match it. Just be sure it's discharged.
I've replaced them at work but never payed much attention to the actual cost.

I'd also look at the centrifugal switch which connects/disconnects the capacitor. If that isn't working the motor won't work, good cap. or not, good voltage or not. The two pieces must both work for the motor to start. Reread Rick's post.