Air Conditioning Malfunction with Genny Power

[TopHattandTails]

Angela - try the fuel filters first (keep it simple). If that doesn't do it, likely the regulator on the board. They have a charcoal contact and vibration shakes it loose eventually. You can try bumping it up (slightly higher output is better than slightly lower output, especially for compressors on the a/c's and frigerfrator). Careful - its REAL sensitive. It will be a pod looking adjustment. There are replacement boards available (form the same guys that produce the Hatt Alarm System board), and there not too badly priced. Cheaper replacing the whole board than having the regulator rebuilt. Google the part # and you'll get some hits. If you need the web address - PM me, I'll look it up.

Guess how I know....the new board goes in this weekend...

[Angela]

WOW!! Thanks everyone. I have tried to replicate the problem on shore power - no can do! This only happens on genny power, and Pascal, this is a new problem. I haven't had a problem with these blowers since they were replaced for the last time back in August. You must be thinking of one of my other gremlins somewhere. I've had the boat out for the past 3 or 4 weekends straight, and this only does happen on the genny. Works just fine when I get back to the dock. When it misbehaved yesterday, it was when I fired up the oven, so there was a bigger draw on it. The AC on the lower level ran all day without a problem.

It has been a while since I did the fuel filters down there. And I never forget that litte one on the genny engine in addition to the Racor. I used to have to change them about ever 20 minutes when we were having nasty fuel problems a few years ago. I can't remember what's in the Racor currently, but I think it's a 2 micron. They come on 30's, 10's and 2's, right? Isn't the brown one a 2? (Red is 30, and blue is 10, right?). I'll change the filters first and see what gives before messing with anything else. That little filter on the engine is a bitch to change, and I believe that one is a 15, so I like to keep a 2 in the Racor to protect the one that is a bitch to change.

[captddis]

How about checking the voltage and Hertz First! That will give the answer.

[krush]

How about checking the voltage and Hertz First! That will give the answer.

Late to the discussion I am, but I agree with this guy!

58-62Hz isn't going to hurt anything. Hell, on this lovely island our power fluctuates from 59-61 (even though it shouldn't, but that's a different story).

Generators make pure "real" sin, unless they are inverter generators and they may not make it...because they make DC and invert it into AC.

[REBrueckner]

Here are specs for a current 11.5KW Cummins Onan diesel generator (just picked that one at random) :

Random frequency variation: Will not exceed +/-0.5% of
its mean value for constant loads from no load to full load

Voltage regulation: No load to rated load +/-1.5%

Random voltage variation: Will not exceed +/-1% of its
mean value for constant loads from no load to full load

http://www.cumminsonan.com/www/html/...ets/a-1478.pdf

How does a "constant load" vary from "no load to full load" ????

[Mike36c]

I bought a cool simple gadget called 'Kill a Watt' and plugged it in an outlet next to my electrical panel. For around $20 it displays real time digital volts and hertz, great for monitoring genny and crappy Bahamian shore power. The sick growl an A/C unit makes at 95volts and 50hz has launched me out of bed many nights in the islands.

[hibanx]

Check the specs on your generator for what the correct Racor filter is. The 3 micron filter could be causing a restriction. Did this problem start after you started using the 3 micron Racors?

[ThirdHatt]

I think running a 2 micron Racor is going ro result in many more fuel problems and filter changes than necessary. I don't know anyone that runs 2 micron filters in their Racors, at least not for very long anyway! For cleaning your fuel, yes but not for regular day-to-day use. I would be a bit surprised if the last chance filter is a 15 micron, but even if it were that just means that the manufacturer is comfortable with anything smaller than 15 microns being spit through the injectors with no problems because that is their "last chance" filter. In that case a 10 micron Racor would still allow you to extend the service interval of the on engine filter while still filtering down more than the manufacturer suggests and you would not have to worry about excessive fuel restriction.

Most on-engine filters are 2-6 micron to my knowledge but I would be running a 10 micron if I were you and I knew I had clean fuel. That way everything above 10 microns is caught by the Racor and anything smaller is either caught by the on-engine filter or burned by the engine. Less chance of fuel filter issues under load which is quite important on a charter boat especially if you have only one generator.

[Angela]

Does the 2 really cause problems? Well, I don’t know. That filter has been in there for about 500 hours now and this is my first hiccup - not even sure it's related to the filter yet.

Maybe, generally, the 2 does or can cause problems, but I guess this genny has been the exception, and I’ve been lucky. I don’t know the answer; I can only tell you what mileage I’ve gotten out of the 2 this time around. I’ll be changing the filter this weekend, in between installing new water pumps, and shopping for hardwood floors. Going to be a busy weekend.

By the way, Ed did check the voltage and hertz on the genny, and at the time he was checking it (at several different times), it was all within normal limits. This problem that has developed just recently is intermittent and unpredictable. The one time I caught it acting flakey, Ed was in the shower and couldn't come running with the meter. By the time he got to it, it was behaving again. I suppose if we were monitoring it with a meter on a continuous basis, we might see something that is out of whack, but we can't stand there like for hours on end. It's time for a filter change anyway, so I'll do it, see what happens, and go from there.

[Trojan]

[QUOTE=ThirdHatt;188427]I think running a 2 micron Racor is going ro result in many more fuel problems and filter changes than necessary. I don't know anyone that runs 2 micron filters in their Racors, at least not for very long anyway! For cleaning your fuel, yes but not for regular day-to-day use. I would be a bit surprised if the last chance filter is a 15 micron, but even if it were that just means that the manufacturer is comfortable with anything smaller than 15 microns being spit through the injectors with no problems because that is their "last chance" filter. In that case a 10 micron Racor would still allow you to extend the service interval of the on engine filter while still filtering down more than the manufacturer suggests and you would not have to worry about excessive fuel restriction.

Most on-engine filters are 2-6 micron to my knowledge but I would be running a 10 micron if I were you and I knew I had clean fuel. That way everything above 10 microns is caught by the Racor and anything smaller is either caught by the on-engine filter or burned by the engine. Less chance of fuel filter issues under load which is quite important on a charter boat especially if you have only one generator.[/QUOTE


I would go with the above Angela. I would think that your filters may be clean. But under heavy load you may not be able to maintain the proper fuel flow requirements of the generator. Change the filters get the real little ones out of there. I think you will see a big change. You most likely are showing a voltage and rpm drop. Which will produce a low cycle drop. No new DC controls should be bothered by low ac cycle.

BILL