Generator struggles to start A/C

[rattle_snake1]

This season I am having issues with my Honda EU3000i handi generator starting the A/C compressor. It has worked fine the last 7 years, even using the Eco throttle setting (low idle) at 115+* heat or at 8000’ elevation.
A/C is a Dometic 13.5K BTU unit from 2003. On shore power (dedicated 20A) it starts fine within 1 second, drawing about 20A max
On the generator (in Eco mode), using a 30A twistlock adapter, the generator boggs down and the overload protection on the compressor actives, then tries again and will usually start and run compressor. If I disable the Eco feature and let it run at a higher RPM, it will start A/C but goes to locked rotor current for a second or 2.
So I bought a hard start kit and took some measurement before and after. This unit already had one, so I left it and installed the new one in parallel. There was no change in performance, so the old one is likely OK.
Min voltage = 58 Volts. (!?!)
Max current = 56 amps (RLA is 59A)
So the generator still produces 3kw as it is rated but the low voltage is not tolerated by the A/C.
So given the A/C starts nice and quick (even after a short cycle) on shore power, I suspect the generator. I serviced the air filter, spark arrestor, spark plug and changed the oil. All was well before so no change after this. Unit blinks twice so about 200 hrs on it. Runs fine at idle and full load. Starts on 1st pull as always.
So it appears the generator has a load transient issue that it did not have before. Under stead state conditions with A/C running, output is right at 120V drawing 12A, like it should.

What to do next?

[rattle_snake1]

The fan runs at all times so they don't start at the same time, unless it is at 1st startup.

I re-installed the tested main split capacitor, and tested operation before installing cover. It struggled to start. Hooked up factory HSK, same result. So something else is the issue, not the HSK. Inconsistent behavior.

The shore cord plug was suspect from getting hot too many times (bad adapter that was replaced previously) so I replaced it. No change. I inspected the connection from the shore cord into the load center. everything was tight and clean.

I think that there is an intermittent poor connection.

This leaves only the wire from the A/C to the load center. So I guess next step is measuring voltage drop (either running or at start up) at gen, load center, and A/C to try and determine where issue may be.

[rstanek]

Try adding a delay timer on the thermostat for the fan so both the compressor and fan do not start at the same time, 8 to 10 second delay, I did this to mine two years ago, it made a significant difference.

[rattle_snake1]

Thanks again Wizard, really appreciate the help. I'll try isolating the converter, easy enough.

[MrWizard]

Strange
Seems like there is some other capacitance on the line

I can only think of two places that might be possible

In the generator or the converter

You might try there start test with the converter unplugged or circuit breaker turned off
Sounds weird, but i can't think of anything else

[rattle_snake1]

OK. I spent some quality time on the roof.

Test #1:
I removed the old HSK (hard start kit) and left the new one on. A/C wouldn't start even with gen at high rpm.

Test #2: I removed both HSKs. A/C comp started right up. switched gen to eco (low rpm). Starts great like this too. (like it used to).

But this goes against expected operation. Yes the A/C doesn't 'need' a HSK, as it is a factory option to have one. But a properly functioning one 'should' help as it increases phase delay to start winding.

Test #3
Just to confirm, I reinstalled the old HSK. It struggled to start A/C.

I removed all caps and tested them. All are in spec including the split cap (5u/30u). I tested the PTC relays, they are closed when cold/no current like they should be.

So it appears possible that the comp motor likes only 30uf and not the parallel combination of the 50u of the old and 100u of the new HSK.

BUT, WHAT changed? I was fine before with the old HSK.
I can just leave the HSK off, but my warped mind must understand why. Perhaps there is another issue I haven't found yet.

[MrWizard]

yes disconnect them
to me it does sound like one of them is failing

the honda genny with low hours, should NOT be having problems

[rattle_snake1]

The dometic 57912.532 has 3 terminal fan/start cap, and what looks to be a factory installed 'COMP STARTER' (see sch link below) which is a PTCR (+ temp coeff. thermistor) controlled relay and a cap.

I installed a Supco SPP6 Hard Start Kit, which is the same thing
http://www.supco.com/web/supco_live/products/SPP6.html

Both of these sense start condition and close relay to put their cap in parallel with regular start cap. ('C' to 'HERM').

Dometic schematic
http://www.modmyrv.com/2009/05/27/rv-air-conditioner-hard-start-capacitor

I guess I can diconnect both and see what happens as well...

[phillyg]

A Honda Handi only puts out 2700w, but if it previously handled the AC, something is wrong with the AC or genset. I suggest you find a Honda-certified repair shop to have the genset serviced. It could also be the AC but I don't know didly about them. I had a Handi but had to upgrade to a 3400w genset because it couldn't handle my new 15k AC unit.

[MrWizard]

are you sure, there is a 'start kit' in place already
and Not just a Normal start/run capacitor
which of course could be failing

IIRC
the mfg add on , would be a PTR
which is a timed delay thermal controlled relay
in addition to the 'run' cap

and not the same thing as a Supco hard start

[rattle_snake1]

Thanks Wizard, I will try that and report back.

[MrWizard]

I think it's the A/C
Remove the old hard start
A new kit parallel to an old bad kit
Will still act bad
You replace an old part
Not put a new part across the circuit
The old bad part will still screw things up
You have nothing to lose but a little time on the roof