Hard Start kits: Supco SPP6 vs. Dometic #3310727.015

Micro Air Easy Start is worth every penny. 2500 watt generator handles the air with no issue now.

OP here. Learned a lot about inrush current/LRA in the last 6 years. Discovered start capacitors (with or without a PTCR) can potentially lower an RV a/c compressor's LRA about 3-5%. A Micro Air Easy Start (not available back in 2014) can lower a typical 55-70a RV a/c compressor's LRA as much as 50-60%---*huge* performance advantage vs. a standard start capacitor! Discovered paralleling two Honda EU2x00i's does double the continuous current output, but only increases the inrush current output about 10%. A whole lot cheaper (and a whole lot more effective) to purchase a $250-$300 Micro Air Easy Start vs. a $1000 2nd Honda to help reliably start an RV a/c.

Chris Bryant wrote:
There is virtually no difference between that Dometic part and the Supco SPP6- both are PTCR based start devices. Supco does not recommend the E series for RV applications- because if you shut the compressor and try to restart it right away, the E series will put the start cap in the circuit, a PTCR device will not. My response to that- doesn't short cycle the A/C (most new thermostats will not let you anyway).
DuoTherm does make a couple of better options- p/n 3102903.006 , which is a true potential relay (unlike the Supco "E" series quasi potential relay), and a really good, though very expensive start kit, the SmartStart- unlike anything else on the market (at ~$370, it better be :) ).

Another option I am looking at is the 5-2-1 compressor saver- a true 3 wire potential relay.

Note that the benefit for the non-PTCR type kits is really only in running off an undersized genset- they keep the start capacitor in the circuit until the compressor comes up to 75% of speed, which takes a fraction of a second longer if the genset bogs down.

I strongly agree with the 5-2-1 compressor saver. I was a Facilities Manager for a large school district fo 17 years.. We had thousands of 5 ton units here in the desert. The ONLY "hard start" kit that would consistently start old worn out units was the 5-2-1. We tried every brand available and the 5-2-1 was the best.

The thing missing from this thread that didn't exist is the MicroStart technology - which didn't exist in 2014 and does now.

While I've not added one in lieu of my Supco unit - all the folks on this site speak favorably about it.

One thing to remember, as temperature climbs, so does the demand for electricity (in terms of Amp draw).

Generators lose 10% of their available output every 1000'.

Increase the temperature, and elevation and you're losing the ability to provide enough energy to drive the AC unit.

I'm not sure how the Microstart can (or does) mitigate that lower power output from the generator due to elevation and increase demand from the compressor due to temperature increase.

I got quite an education on this about 4 years ago. Most of the articles you find online the people have no idea what they are talking about or doing! Hint, as soon as they bring out a Kill a Watt meter, they don't have a clue. Takes a quality clamp on meter to measure inrush current.

My Honda 2000 would not start my Duo Therm 11k unit. Get a Suppco they said, will work 100%, easy to install. Put one in and wow! The AC fired right up, in 70 degree weather. Some place between 70 and upper 90's it failed to start the AC. Temperature, humidity and elevation affect AC and generator operation.

So on the net, at what point with a hard start running an AC that is oversized for the genset are brownout conditions experienced, at what temperature, at what elevation? How long will it take to burn out the AC or genny? The electronics in the Honda are in the $500 area, not something I want to make the wrong guess on.

If you try to run an air conditioner during a brown-out you risk damaging it permanently by burning the motor out. The reason is the air conditioners and many other motor driven appliances require a great deal more power to start than to continue running. If the power isn’t available the motor continues to draw excess power none-the-less but fails to start and eventually overheats and burns out.

It is possible that modern appliances have protections to prevent this from happening but it has been a traditional problem so it’s worth consulting the manufacturer to ask their advice.


So for me the options are bigger genny, smaller AC or a Micro Air soft start.

I was able to use an 8k window unit, which the Honda 2000 runs under all conditions. I did add a hard start to it, so I can run in ECO mode.

Only my opinion and worth what you are paying for it.

Salinahocutt wrote:
Hard Start kit main function is that, increased compressor starting capacity and saver your compressor. It kick start to your compressor in your ***Link Removed***HVAC System. It is more faster, up to 10 times and more efficiently with your run capacitor. It so many issues like repair commercial refrigerator and freeze, multiple AC units problems, If your AC sometimes trips or shuts, etc. https://www.refrigerantrecoverymachine.com/best-hard-start-kit-hvac/

Holy Thread Resurrection, Batman!:S
A 6 year old thread brought to life!

Hard Start kit main function is that, increased compressor starting capacity and saver your compressor. It kick start to your compressor in your ***Link Removed***HVAC System. It is more faster, up to 10 times and more efficiently with your run capacitor. It so many issues like repair commercial refrigerator and freeze, multiple AC units problems, If your AC sometimes trips or shuts, etc. https://www.refrigerantrecoverymachine.com/best-hard-start-kit-hvac/

Model# 8335D8564 ...?

ford truck guy wrote:
I read somewhere on this forum how you can tell if your AC already has a hard start kit on it by the serial numbers ?? I cannot find that thread , can anybody help? Chris Bryant >??

Only for Coleman (RVP) units- the second number of the second string tells what it has-
like 7333-6664
If that number is a 6, there is no start kit, a 7 means PTCR kit, 8 or 9 means a relay based kit.

I read somewhere on this forum how you can tell if your AC already has a hard start kit on it by the serial numbers ?? I cannot find that thread , can anybody help? Chris Bryant >??