Air Conditioner Capacitor - Maxum Boat Owners Club

Derek in AZ · 07-09-2012, 05:44 PM

Hey Gents,
Heres the issue. My air conditioner on my 1998 maxim 3200 SCR works fine when connected to shore power. However, when i attempt to run it off of my generator (4.5 BCG A) it "Browns out" and resets the computer when it attempts to turn on the compressor. I am fairly sure that this has to to with the starting capacitor. But wouldn't it brown out on shore power as well if it was a capacitor issue? I also tried shutting all other ac devices off except for the Air and it still won't run. Seems like a really high current draw. I have never heard of a generator putting out less than its rated capacity... they seem to either work as rated (or near) or not work at all. Any help/guidance is much appreciated.

DL

pascavone · 07-09-2012, 05:54 PM

the generator has a float switch to regulate the load, this could be at fault.

that A/C has a start module with also spikes the load at first start up.

I'd first test the generator for a load test, your pulling 30amp then the a/c load drops to 15amp when running.... approx.

shrew · 07-09-2012, 09:03 PM

My 2000Kw Genny only puts out 13.3 amps. What is the amperage output on the genny and the amperage draw at spike when the compressor first starts? Do you also have your hotwater heater turned on? Try turning EVERYTHING off, then turn on ONLY the A/C and see if you can reproduce the issue.

Derek in AZ · 07-10-2012, 04:32 AM

Pascavone. Is the float switch a function of the carb? Meaning that it regulates RPM's and therefor the capacity of the generator?

As for doing a load test... i have shut everything off at the AC (alternating current) Load center except for the AC and it still greys out. I don't have an amperage gauge installed anywhere to give me an idea on what its pulling during normal operations nor do i know a way to test load with a multimeter. The manufacturer of the generator states that the rating on the generator is 37.5amps. While i don't expect it to put out that total amount i expect it to be close. My shore power is 40 amps and i don't have an issue running everything on the boat at the same time with the AC on. Nor do i have an issue running all of the other AC devices off of the generator at the same time without the AC running. In my view it has to be something with the AC. Is there a capacitor installed in the factory unit already?

pascavone · 07-10-2012, 06:04 AM

first, the A/C is about as expensive as a new generator.

The float switch governs the electric out put for CLEAN POWER.

The engine speed is more a product of the RPM and the carb, which is mechanical, not electrical.

the a/c is working on CLEAN shore power, opposed to DIRTY un regulated generator power.

if your generator is varying even 1,000 MHZ its DIRTY power and pissing off then power regulator on your main panel.

I'd start with a mobile marine mechanic who can bench test the generator.

The A/C repair guys love to pull the unit out and bench test it, and if yours is working, they will put it back in your boat and blame it on your generator anyway.

Derek in AZ · 07-11-2012, 01:30 AM

So I went out today and did some work on it. When i arrived I notice that the shore power is a solid 120V when not loaded. The Generator unloaded was bouncing between 108-112V. So, i adjusted the idle to bring the unloaded value to 124 (normal per the westerbeke manual). This almost solved the problem... Now, the AC attempts to start for just under a second before it "Browns out". I just purchased a hard start from a local AC guy and will put that on tomorrow. I think this will fix the issue. Ill post my results. Thanks for the help.

DL

pascavone · 07-11-2012, 04:24 AM

i don't know what a HARD START is.... i not b so smart...

capav8r · 07-11-2012, 10:32 PM

I would also check to make sure you don't have any corrosion between the gen set and the panel. Your voltage would read normal, but the ability to carry a current would be reduced. You should be able to see this by connecting your digital meter at the air conditioner and see if there is a big voltage drop when the a/c tries to start while on the generator.

anderson1308 · 07-17-2012, 05:00 PM

Try changing the spark plugs... I know it sounds strange, but my westerbeke would not power the A/C (A/C would stop after a few seconds with genny)... After new plugs works like a champ no brown out no shut down...

shrew · 07-17-2012, 05:14 PM

Hi anderson1308, welcome aboard!! Interesting solution. I think of a generator as having two 'sides' if you will. The gas powered engine and the electric generator, with the gas powered engine running the electric generator. The Gas powered engine, I tend to reduce to the triumvirate (Air, Fuel, Spark). Unless I' misunderstand, I interpret a 'brown out' as the gas engine is running, but no VAC is being delievered from the electric generator side.

In this case, if the gas engine is running, how would replacing spark plugs resolve this issue? My simplistic thinking says either the engine is running or it is not. If it were running and the generator is in a 'brown out' condition, I can't seem to warp my head round how replacing plugs would help. I'm not saying it didn't in your case. It's just me being an simpleton, or I don't clearly understand the problem.

anderson1308 · 07-17-2012, 08:20 PM

I thought the same thing, however after much investigation my Westerbeke, and for that matter maybe many other gennies, produce power proportional to the rpms. So I reasoned that if the engine side is running slower, due to heavy load not being compensated by proper "triumvirate (Air, Fuel, Spark)" then it stands to reason that less production will occur on the electrical side. Hence the "brown out"...

I do not disagree with your statements, just trying to wrap my mechanical brain around that invisible genie... electricity...

another reason I have not paid an electric bill in years... when I can see the stuff I will pay for it...

shrew · 07-17-2012, 10:24 PM

OK, I'll buy that. Thanks, and again WELCOME!!

Derek in AZ · 08-10-2012, 06:54 PM

Just wanted to update everyone on what I finally found out about this issue...

After contacting a friend of mine who is an electrical engineer and conducting tests with a bunch of fancy equipment that he brought out, we determined that the coils in the generator are not functioning properly and thus not providing current at the 50-60hz range that the AC unit is rated at. While the generator does indeed provide 120V current the AC motherboard is very sensitive to the phase of the voltage and will not function properly when the current is not "clean". However, the refrigerator, ice maker, water heater, and most consumer electronics and not that sensitive and will run fine with the "dirty" power. For now that is... according to the engineer the dirty power will eventually corrupt the other AC devices and make for a very expensive trip to the shop. Thanks for the input.

DL