[Brad Townsend]

Still trying to find out if there is an allowable variance on the capacitor ratings.
Any electrical engineers out there?

[Fulltiming]

I am not an electrical engineer BUT where possible it is best to stay within -0% +10% on RUN capacitor ratings. Long term, using a capacitor that is significantly too large (several times the recommended value) MIGHT cause the fan to run hot.

Grainger sells a 20/5 dual run capacitor but it is round so you would have to check to be sure that it would fit. https://www.grainger.com/product/TITAN-P...tor-30D631

Controls Central sells an oval 20/5 http://controlscentral.com/eCatalog/tabi...Asze8P8HAQ

[Richard]

Can someone take a pic and post the schematic?

Brad, have you confirmed the wiring matches the schematic? You said Newell wired it backwards. Exactly how do you do that with AC power?

Does the wiring match against he other units?

[Fulltiming]

Here is a schematic for the Dometic AC unit from my 1992 Dometic book.



http://newellgurus.com/gallery/albums/us...ic_001.jpg

[Brad Townsend]

The tech wired the compressor backwards. He took over the job the next day after former tech took it out. made the compressor into a heat pump, it putting out heat instead of cold air. The wires I am talking about are the ones on top of the compressor.

So today I received a hard start booster capacitor on Richards recommendation. Installed in a couple minutes and so far works great. 
Doing a web search about these items, I believe it would be advantage for rvers to have one on each AC unit. This would safe guard the compressor from low voltage startups that would cause otherwise high amp draws.

These systems are like home systems and capacitors are the number one problem for tech calls mostly fixed with new replacement capacitors and in addition they would add a hard start booster capacitor if they found the main power to be on the low side.

I found a company that has USA made capacitors warranted for 5 years not 1 yr like the foreign units.
https://www.airstarsupply.com/products.aspx?cat=265

This is the hard start capacitor I now have in my AC unit
https://www.amazon.com/gp/product/B00DZU...UTF8&psc=1

This is the Microfarad meter to check my capacitors. 
https://www.amazon.com/gp/product/B00AF1...UTF8&psc=1

[Brad Townsend]

I know the tech installed the unit plumbed backwards and not sure if it was before that that I herd him say the wires were backwards.
I forget the exact order of things that happened but do know the new compressor had to be taken out and rotated, perhaps that is what made the heat in the coach.
Whew, what a mess I just hope my ac keeps working, I need a break from fixing on the newell and start to enjoy it.

[Fulltiming]

Several years ago, I added a hard start capacitor to one of my AC units with very positive results. Richard steered me to the same one you listed.

[Richard]

Interesting.

There are two possibilities on the backwards business. One, it was plumbed backwards. On the compressor I put in the suction and discharge tubing was different sizes, so you would really have to work at it. Two, the way you make an AC motor run in the opposite direction is that you reverse the run wire and the start wire. In other words, if the start wire is wired straight to hot, and the run wire from the compressor is wired to the capacitor then the motor will turn in the opposite direction.

The problem with that is that the start windings are light gauge wire compared to the run windings. Meaning the motor windings could overheat if the motor runs backwards for extended periods.

On a new compressor the wiring is usually clearly marked for start, run, and common.

[Brad Townsend]

Update:
The ac unit is still working and is putting out 45 degree air, not sure why it first put out the 35 degree. The hard start makes it work but when the system starts up I watch the amp meter inside the coach and it jumps up to the max (50 amp) but goes right back down. The other units do not pull that hard not even half that. So I am wondering if there was some damage done to the compressor. I did some research on the capacitor asking other HVAC companies if the ratings could vary even a couple MFD and every one said they wouldn't recommend it. So I did find info on the compressor that confirmed it called for 25 MFD and I see the tag on the fan motor is calling for 5 MFD. The Capacitor that Newell said came with the new compressor is 25/7.5 so I found a 25/5 and will put that in assuring the motor has what it should have.

[Richard]

Brad,

Keep an eye on the compressor, as I said earlier, wiring it to run backwards can burn up the start windings.