Air conditioner issues

Dream_Inn

So, this one is a bit strange and started last year.  I have a 12kbtu until in the back and 16k in the front.  When I'm on shore power, all work great. When I'm out on the hook, and running generator, the 16k front unit has a startup issue and restarts when, I  think, the condenser starts up. Maybe it is drawing too much power?  But, the generator seems fine and no breakers blow.  Last year it would take a time or two and then be ok. This weekend I could not get the front to work.  I believe, not positive, this has only been with heat. No sure though. I also noticed at times when I first start it that the temp on the panel is way off.  Usually lower, but it changes quickly within a few minutes. Thinking about it, I  know the temp change is also with ac, not just heat.  

Any ideas?  Everything else is fine on genny and it runs nicely.  I'm actually ok replacing the dam thing, because it's original and I'd love to have one with fiberglass pan and quieter. But, the engineer in me wants to figure it out.  I have some pieces like a display and electronics board from a friend's old unit I can try first.  Just seems odd that it works fine on shore power.

Luckily the back unit and a small electric heater was good for the night.👍

Also, if I buy new, what are your recommendations? I remember some nice ones people where getting over the last few years.

YYZRC

Weak capacitor? This coming from a guy who successfully fixed a ductless unit once and has no other knowledge or skills. 

Dream_Inn

So, capacitor is my first thought and was the one thing I  mentioned over drinks Saturday night.👍

Liberty44140

Have you had a chance to look at the capacitor to see if the top is mushrooming? That is one sign of a bad capacitor other than the usual breaker flip at start up. Heat mode does use more power than cool mode so it would make sense that you see this in heat and not cool. 

Grahamu

I would suspect a voltage problem if it works on shore power. Have you checked no load voltage when on shore power against the genset voltage and then turn on the A/C unit and watch voltage drop on startup again compared to either supply?. Your genset might need an adjustment to increase voltage. Turn off all other loads when checking.

raybo3

Need more info, does it do it when both are running of by itself? Did you check all electrical connections at the unit? Try putting a volt meter on the unit and see what the voltage drop is. Maybe the age of the compressor is drawing a little more on start up. Another thing you could check is if the rpm's on the genny drop a little on start up of the unit. Just thinking out loud here....... 

Dream_Inn

So, a little more details.  I have turned everything off when on the genny and only tried starting that AC, it cycles power when trying to turn on.  Next scenario, I have the other (smaller) AC running on the genny, when I turn on the front AC, it cycles power, but also causes the other AC to cycle power.  Yes, like it draws too much power at startup.  I don't believe it has anything to do with the genny, but I could absolutely be wrong.

I am going to get my meter out and start probing a bit more, but really didn't bother Saturday night after having several drinks.  I was also ok at the time with an electric heater and the rear heat working. 

I'm also able to load the genny up with the range, water heater and a few other things and the back AC kicks on fine, so to me that is saying the genny is probably ok.  Again, I know that isn't completely taking it out yet.  I'll connect a meter into the AC outlet the next time and see what happens when I try it. But, if the AC puts a huge load on it, the voltage will get pulled down.  Doesn't mean the genny needs adjustment necessarily (it could though). 

I would also like to hear recommendations on AC units.  As I definitely want one with a fiberglass style condensation pan for sure!

YYZRC

I think the one that @aero3113 got is great value. 

aero3113

YYZRC said:

I think the one that @aero3113 got is great value. 

Yes!!
Highly recommend, very quiet!

Heres a link

https://www.marinaire.com/Products-s/12.htm?gclid=CjwKCAjwo8-SBhAlEiwAopc9W6C3VddACn38C0xdKompSUnfFiihcHbTm_E3N3BAEOEK51XW_wG9ERoCxKsQAvD_BwE

Grahamu

I still think a comparing the  shore power voltage and genset voltage at startup would be useful information. Maybe you have a corrosion problem at the genset terminals or genset breaker which is reducing the wattage available. Can't help with AC info as I have not looked into changing mine.

Handymans342

@Dream_Inn Check capacitors unhooked with proper meter or just replace them. 

captkevin

You can buy hard start capacitors that have more capacity & give the unit the extra boost they often need as they get older. Might solve your problem.

raybo3

@Dream_Inn If the caps are OK then something has changed. It really could be only two things. The compressor or the blower motor. Do you have a clamp on amp probe? You may want to take current reading on the compressor and the blower motor. I would assume those are to only two things that could cause your problem.  

Dream_Inn

I appreciate all the comments.  I will check the caps first. I also have a regular fluke multimeter, but I also have a fluke mater that has a clamp.🙄 Electrical engineerh as to have his toys. Maybe I'll make some time this weekend.  We'll be out on the boat for 4 days.

@raybo3 it does seem to happen when blower tries to start.

And yes, that one that Aero bought is the one I was remembering!

Oh, and @Grahamu, you are right, comparing those two are a good and easy check.

raybo3

@Dream_Inn if its the blower motor that should be a fairly easy swap. Much cheaper than a new unit......;. Just say'n

Dream_Inn

So, I wanted to follow back up on this.  I was finally able to play a bit more with this over the weekend.  I was able to get it to happen also with the rear air conditioner if I loaded up the generator a bit more.  So, I decided it was an issue with the generator under load.  I started with the easier stuff, changing out the plugs and both coils (I carry spare coils, so not a big deal).  Still the same, but the plugs were due for changing.  Next I started digging deeper. I remembered I had installed a new controller less than 2 years ago (my wallet still remembers it for sure).  Which meant I had the manuals for configuring and setting it all up.  It showed me the details to check on output frequency, voltage, gain stability, and volt/hz.  So I double checked the config settings, all was good.  I then checked output voltage and frequency, all looked ok.  So, I checked voltage and frequency under load, specifically when the front AC would try to kick on.  Frequency looked ok, but voltage would drop more than allowable (front AC cause it drop like 70 volts, back one - which would come on - dropped to 93 volts).  So, I made a slight adjustment of 2 volts to output voltage, but no luck.  Next, I changed it to 125V.  It worked and everything on the boat now works all loaded up at one time or starting them up while other stuff loading.  For now I'm going to say this is good.  I will continue to monitor it and I will check cabling, as maybe there is some corrosion or something that needs tightened on the generator side, thus possibly causing more resistance?  I also believe it may have just needed the adjustment since my installation of the controller.