AC Hard Start Kit

[WoodworkerTom]

I bought a house a few years ago and I notice that the lights flicker a little when the central AC kicks on.  a coworker mentioned there is a Hard Start Kit form a Company called 5-2-1 that fixes that issue and allegedly extends the life of the compressor.

I have never heard of this before, does anyone have any experience with these kits?  Is it worth it to put these on the compressor?

[Phil Thien]

I've only heard of using them when required.  That is, older units that won't start w/o one.

I think it is basically a large cap that gives the motor the oomph needed to start-up.

[daddo]

First you might check the elect service and make sure it is adequate for the load.
Many new systems don't require a start assist but if you have a TXV metering device on the indoor unit it doesn't hurt to install one.

Otherwise, you may have a compressor hard starting because of a weak run capacitor or a start winding going bad.

A slight flicker is normal. In fact, as I turn a system on at thermostat, I look for the lights to "flicker" to let me know the outdoor unit is being energized.

[Matt Williams]

When I had my system installed they added one.  The tech thought it was a great idea and since it was free to me I didn't worry about it.  Heat pump is still running fine 12 years later.

[blackhat]

For peace of mind, I would do a voltage drop test at the unit and breaker panel including the main for the house. A high drop when the unit starts could be caused by degrading connections somewhere in the feed to the unit.  If those are all ok, a hard start may extend the life of the unit and cure the flicker, it won't hurt anyway.