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.

I too would avoid installing a new R410A condenser with an existing R22 coil a few years down the road. It's not easy to flush out all of the residual mineral oil that will remain in the coil -- if not impossible to remove it all. Mineral oil and R410A don't mix, and you don't want to contaminate a new system down the road. Unless the coil is leaking (in which case you could replace the coil at this point, but should plan on replacing the coil again when a new outdoor unit is required), I would keep the current coil matched to the condenser you're keeping and replace both the coil and condenser when the condenser fails, as TD suggested. I also recommend the TM8V furnace with variable speed motor. Here's a link to an article on the importance of variable speed motors -- a bit technical but reasonably comprehensible. Here is a link that might be useful: http://contractingbusiness.com/columnists/falke/variable_speedfans0324/

"1. When the compressor was installed, could the unit have been damaged by his welding (overload protection opening periodically not allowing compressor to start?) He spent a long time heating the pipes. I solder and weld myself and it took him a long time heating pipes on a nearly empty bottle, which he had to go and replace. Could heat transfer have damaged the compressor?" Refrigeration lines are brazed, not welded. As long as he had a nitrogen purge running while he brazed to prevent formation of copper oxides that can then scale off the only thing you can mess up is to overheat the valves on the condenser. "2. Need to install hard start kit? He did try another capacitor but it made no difference. He tried what he called a hard start kit, which just seemed like a different value of capacitor, but that made no difference." Hard start kits contain a timer relay and a larger capacitor. They are useful when the power quality is not good. Long runs or low voltage can both prolong start time. A hard start kit provides more phase shift to the start winding and increases starting torque. "3. Could the charge be wrong so the system is out of balance and causing problems? After online research, it seems there should be a scientific approach to charging the system. Would a wrong charge cause the compressor protection to cut in. Would this happen quickly with a wrong charge? " Condensers come with a nominal charge in the unit. The installation instructions will state how many feet of lines the charge is set for. Any changes from the stated values require adjustment of the charge. "4. Could is be a power supply thing? The lights flicker when the compressor unit starts. Unlikely but possible? " When an induction motor like the one used in the compressor start up they appear as almost a dead short on the AC line. The starting current is a couple of times higher than the running current. Look on the nameplate for "LRA." This is Locked Rotor Amps and indicates the peak current required for starting the compressor. If your house feed is low, at the end of the line, or even on a marginally overloaded POCO circuit the voltage can drop under the starting current. This causes incandescent light bulbs to dim and can extend the start time of the compressor. A hard start kit can help under these circumstances. You can also try complain to the POCO and see if they can check their portion of the feed.

OEMs don't have an economic interest that's served by extending the useful life of their equipment beyond the warranty period, especially if doing so adds to the upfront cost as would be the case with hard starts. Distributors that sell the equipment are there to also sell me the garbage that causes damage to a compressor over time. It's a vicious circle to say the least. I know better now (2023) than say 25 years ago... from the perspective of doing HVAC for 29 years. Just because someone or some entity within the HVAC realm is attempting to sell you something doesn't mean you should buy it. Nor that I should sell it. To gain trust --- home owners trust me with my recommendations for real reasons. My market in Katy, Texas has knuckle heads running around for free advice. I don't do free advice except here on this board to more or less explain the hidden cost of just doing something because someone is selling it. If the advice is free it's not worth anything to begin with. My advice is worth what you pay for it in person. If you don't think so you're fine by me to go that route. I know I can lead a horse to water, I can't make him drink it. I can print truth(s) here all day long I can't make you believe it. The best case is to buy the OEM spec hard start kit for a particular unit that currently doesn't have any start up issues and doesn't need the hard start to start --- the manufacturer specifies when one is required for certain applications (like long line set application). As I have stated before required hard starts are different electrically from one compressor to another, size of the compressor etc. Put the wrong one on your AC unit and you're doing damage in small bits at a time every time the unit starts. Extending the life of a unit by adding a part is just regurgitated rhetoric used to sell you something in most cases. It took me a good long stretch of my career to separate the facts from fiction in this regard. When the hard start fails and it will along with the run capacitor -- these two could be responsible for the demise of your compressor in the future. It may not be evident / hard to prove in many cases what caused the compressor failure. But I thought you said it won't hurt anything? Yes provided you put the right one on your system, maintain it properly, replace the hard start again when it is determined thru a maintenance visit that it's needed. What I know for sure is that many people have trouble remembering to replace their filter, get maintenance done... not just done but done properly. If you're worried about what is reasonable in terms of cost to do this right... leave it alone if you don't have the money to do it right AND make sure it is done right. The manufacturer made your unit the way it is to function the way it's supposed to under most installation applications. If you needed a hard start for your particular installation it should have been provided at the time you had your system installed. If you got $250 burning a hole in your pocket? Find something more constructive to spend it on. If you wanted to cut your electric bill you should have bought a more efficient unit like a Bosch 2.0 Inverter. That can cut your electric bill by up to 50%. Like cool stories? Here's a recent one [video below]-- the first AC not cooling call of the summer? In February? (hot climate problems) This unit has no hard start kit -- it doesn't need one yet. I service the Katy, Texas area.