Go to page 5 about halfway down, there was a recent discussion about hard start kits with 30+ posts, "Question about hard start capacitors"

Somewhat true.
Some systems preffer that one is not used due to the type compressor, but I personally don't see what it could hurt.

Single phase motors have zero starting torque.
To overcome this problem a start winding is added and start capacitors are used to produce some phase shift.
The more capacitance present the closer to a 90 degree phase shift and the greater the starting torque (the inductance of the start winding itself cancels some of the phase shift form the start capacitor).
At startup an induction motor pulls current limited by the resistance of the windings (very low) and the inductance at 60 Hz of the windings and iron present in the motor.
The faster the motor can be brought up to operating speed the faster this excess current (and its heating effects) can be reduced the better for long term reliability.
The typical hard start kit adds some additional start capacitance and a 'timer' to pull it out of the circuit.
Just about anything that can reduce the starting current demand will improve long term reliability.
many units come with hard start kits already installed, and just about all the rest recommend them if the run to the unit is long or prolonged starting is present.
A larger start capacitance is never a problem. Capacitors are expensive, and the engineering around the selection of the cap value is to minimize the capacitance needed to save money.

Well said brickeyee!
The "timer" as you mention- don't they still call them "potential" relays? Not knowing the drop out on all units, maybe the "one size fit's all" style start kits in a bag use a timer? I've never asked about that, but I know some of them don't connect to "common" on the unit, therefore the potential may not be used.
Got me curious now!

There are a number of ways of removing the hard start cap from the circuit.
Many use a 'potential relay' to sense when the motor has come up to speed, some have timer relays that only close for a limited time at startup, and some have both to remove the start cap from the circuit if the motor fails to start.
A lot depends on how big the motor is.
Bigger ones tend to get more safety designed in to prevent things from blowing up and burning out.

"There are a number of ways of removing the hard start cap from the circuit.
Many use a 'potential relay' to sense when the motor has come up to speed, some have timer relays that only close for a limited time at startup, and some have both to remove the start cap from the circuit if the motor fails to start.
A lot depends on how big the motor is.
Bigger ones tend to get more safety designed in to prevent things from blowing up and burning out."

Not bad opinion, thank's a lot!

hi all!

My condenser unit (Carrier 38TKB036) for the past year has been having trouble starting. The fan would start but the compressor would not kick in until say half an hour later. The first two years it didn't have that problem only recently. I have a dual capacitor that I replaced and it did not solve the problem. I am looking into the hard start kits below but they call out a separate 'run' and 'start' capacitor. So does that imply I only need to purchase the relay from the kit or I have to change out my dual capacitor that is in there right now? Thanks for the attention.

http://www.captiveaire.com/CatalogContent/Fans/Sup_MPU/doc/Start%20Capacitor%20Relay%20Kit.pdf