A/C Pump Repair

Hampton

Hampton

Air Defense Dept
TECHNICAL Contributor
Nov 26, 2006
7,628
Panama City, Fl
Boat Info
2008 44 Sedan Bridge
Engines
Cummins QSC-500's
Straight Drives
My A/C pump/motor quit running recently. The motor is hot to the touch, so it seems to be trying, though it doesn't hum or vibrate. The strainer had some form of shellfish growing inside so my first inclination is to take the pump apart and check for a shell in the mechanism. Anyone ever had to do this? Any big concerns? It's a small, opaque, beige colored plastic pump attached to a motor like a tiny pool pump assembly.

Thanks in advance.
 
John, If a piece of shell has bound the shaft via impeller the motor would heat up like you mentioned. Have you popped a breaker which would indicate unit pulling hi " I" current ? I build DC motors for a living in Dothan,depending on design you could have a shorted coil in the armature or stator, etc.
 
has the boat been out of the water recently?
the pump may need to be "burped"
take the outlet hose off (the one on the top) turn the a/c on for a moment and see if you get a squirt of water out of the top of the pump. if you do, re-connect the hose and you are good to go.
If you don't you could take the pump section apart and see if it is stuck
usually you are better off replacing the whole pump if burping doesn't work.
once the get hot everything warps out of shape and fixing it rarely works or lasts
those pumps also have a thermal shutdown. if it is still hot when you try to burp it, it will not come on. turn the a/c off and let it cool first.

they are called march pumps
you probably have an LC3
 
That's magnetically coupled, water lubricated, all plastic pump. One of two problems occurred and probably can be corrected. Either something is lodged in the impellers as you suspect, or the pump ran dry and seized it's bearing. I had the ran dry problem on my previous boat and was able to correct the problem easily.

In either case, you can disassemble the pump and clean it out. I think I remember that the gasket is an O ring. The impeller is attached to a large ring magnet and that assembly spins on a plastic shaft. Be careful not to damage the O ring during disassembly; however, you should be able to get a replacement if you do. If you damage the impeller, magnet or housing, I doubt that the parts are sold separately.

Simple inspection will show you what the problem is. If there is no foreign matter, check that the impeller/magnet assembly spin freely. If not, try removing the impeller from the body and check the shaft and impeller body for damage. Usually you can clean up the shaft, and it'll work again.

If you just need to prime the pump, start the genny and bring the boat up on plane. Then, while on plane, turn on the air conditioning. The scoop fitting should force water into the pump, priming it.
Best regards,
Frank C
 
Thanks all. I dis-assembled the pump. It turns freely. I spun the motor - it turns freely. I started the A/C with the pump disconnected from the motor - It hummed, but wouldn't start even when I spun it by hand (carefully).

The motor has lots of corrosion all over the housing. I'm going to shop for a new motor. It's an A.O. Smith MOD JB1S105N Ser 22S U. 115V, 50/60 Hz 2.1/1.8A 2500/3000RPM 1/15 HP Class B iNS 0130-0140-1000. (Now I have the info at work via this site).
 
geriksen,

Shack! AC-3 or BC-3. The motor is corroded and I'm having a bear of a time getting the pump base off of the motor. I found a clamp protector end cap wedged between the pump magnet and the housing. It spun freely, but not freely enough. I could probably re-install it and get it to work fine, but the motor is corroded. Is it an AC or BC? It's $168 for the assembly (or $247):

http://www.electricmotorwarehouse.com/march_pump/series_3_march_pumps.htm

What would you do? The time spent getting it out may be worth replacing it, as bad of shape as it appears to be in.
 
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Better prices: $140 for the AC.

http://www.flagshipmarine.com/marinepumps.html

Catalog Specifications Max.
Max. Max. Int. Max. Wt.
Flow Head Motor Electrical Press Liquid Packed
Model GPM Ft. Inlet Outlet HP RPM Volts* PH Hz Watts Amp Type Connection Materials* in Contact with Solution PSI Temp. 'F' Lbs.
LC-3CP-MD 8.5 19 3/4"FPT 1/2" MPT 1/20 3200 115 1 60 120 2.35 TE/SUB Maroon^ 6 ft. SJT Polypropylene, Epoxy, 316 Stainless Steel, Buna N, Ceramic; when submerged, Sulfil 25 130 8.5
AC-3CP-MD 10.0 20.5 3/4"FPT 1/2" MPT 1/15 3200 115 1 60 150 2.1 AC 3 ft. SJO Polypropylene, Ceramic magnet, Ceramic, Buna N 50 190 7
AC-3AP-MD 10.0 20.5 3/4"OD 3/4"OD
BC-3CP-MD 10.0 20.5 3/4"FPT 1/2" MPT 1/15 3450 115 1 50/60 120 1.7 BC 3 ft. SJO Polypropylene, Ceramic, Viton

AC vs BC is the Viton material in the BC vs Buna N on the AC - Whatever that means.

I'm going to use penetrant to try to get the pump housing off the motor.
 
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John,
Based on the info listed it is AC. If it is as corroded as you say the bearings are most likely shot which severally load the motor up can cause overheating, insulation break down and a open winding or short to ground. You might find a rewind shop in Panama City to rewind and recondition with new bearings for less than the price you found.

Lee Henderson
 
Dometic bought March and Sea Ray only used one pump on most boats. Call John Mass at the marina and ask him which one to be sure.....Panama Marine sells the pumps and usually stocks them.

On a lot of boats, the pump mounts so low and so near a bilge sump that the rust/corrosion is usually what kills them.....and it is worse the smaller the boat. While a re-winder may get you going, you still have a corroded pump, so most folks just replace them. I priced one for my boat several months ago and it was under $200.........
 
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Thanks Frank. I'll talk to John tomorrow.

Lee, how can you tell it's an AC? The BC is made with different internal materials, but otherwise should be identical. Thanks in advance.
 
By the way, my Penetrant did not free the screws after setting overnight. I have an impact driver, but I don't have long screwdriver bits that fit it to access the recessed screws (2" recess next to the magnetic driver).
 
John,
The label info in post # 5 calls out 115V 60/50 Hz. Which is AC better know as alternating current. This is shore power/generator and not from your 12v battery system, which is DC or direct current. By the way be careful working with the motor if you take it apart and reassy and power it up,,,,if not careful you can get a heallty shock from the shaft or housing due to internal wire routing.

With the problems you are having getting the motor apart, I tend to agree with Frank that you will be better off with a new unit. It will have new paint and and the endbells will be plated.

Lee
 
No, No, No Lee, not AC vs DC. Model AC-3CP-MD vs model BC-3CP-MD. I will be replacing the motor no matter what. I don't want to replace the pump if it's a model BC-3CP-MD because they cost $247 compared to $140 for the AC-3CP-MD. I can't get the pump off of the motor - 3/4 of the screws are frozen, so far. If it's a AC-3CP-MD, I'll replace the whole thing for $140. For the labor, it would be foolish not to. For $280, I might prefer to just replace the motor and not the whole assembly.

You obviously quickly scanned my messages. I do that sometimes too. I appreciate all of the help.
 
John,

You can use any marine air conditioning pump that will supply enough water. Cruisair's web site is dead,dead,dead right now, but the flow rate requirement is in the manual for your A/C unit.

Best regards,
Frank C
 
fc3 said:
John,

You can use any marine air conditioning pump that will supply enough water. Cruisair's web site is dead,dead,dead right now, but the flow rate requirement is in the manual for your A/C unit.

Best regards,
Frank C
Click to expand...

Thanks Frank. That's the question. Maybe the model AC........ is only for fresh water and the BC....... is for marine. I'm trying to determine that. The BC cost almost $100 more due to the materials used in construction. Maybe the model AC.... won't last a week in salt. I'll be back at the boat this afternoon. I left the 1/2 of the pump hooked up to the hoses in the bilge. I'll see if it's marked or not. Also, I'll check the owner's manual.
 
John, Sorry for the error. I went back and looked at the post and I did not see the part number disignation change. Did not mean to insult your tecnical ability.

Lee
 
Sorry, I missed the essence of your question. This should help, not like my previous answer.

The March AC- pumps have Air Cooled motors. The LC- pumps have Liquid Cooled motors. You can tell the difference between them since the ACs have cooling vents on the motor housing and the LCs don't. The LCs have small tubes that connect the pump to the motor housing. The tubes usually look like mounting hardware. Sea Ray uses the March LCs since they are sealed. Discounted LC-3s run about $200.

Often you'll find at places like West Marine pumps made by Cal pumps. These are fountain pump with stainless steel pump shafts that extend from the motor's armature to the pumps impeller. These I consider inferior since water can seep past the seal and into the pump body. Also induced stray electric currents can flow down the impeller shaft and into the the water corroding the shaft and prematurely killing the pump. The Cal pumps might be OK on lakes and ponds, but should not be used, IMHO on salt water. Magnetically coupled are the best.

Best regards,
Frank
 
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I carry a spare. Once mine failed on the last night of a trip in the keys, no spare and wife + kids were unhappy without the air. I connected the dockside hose and let it run for the night. The marina manager was none too happy the next morning! So, now I carry a spare pump. I can't remember what model, but, as was mentioned, earlier, the brand and model are not that important. You just need flow.
 
Thank you everyone. The real question right now is the March AC series vs the March BC series. If the AC series is ok for marine use, I'll buy one tomorrow.
 
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