Originally Posted by: richappy 
I have reported in the past that these hard start devices do not protect the compressor from thermal overloads, substation voltage surges, and re-start conditions. Either the unit will just supply high current just below it's rather high trip limit, cause thermal damage to the compressor, and in some cases catch on fire. The surge protector will not help in these conditions, it clips the peaks of the voltage spikes, but retains the valleys.
If you have some technical evidence these items are safe to use, please tell us. They are safe to use in the old high hp compressors, but not in the new high efficiency ones.
I have obtained a good scope and will soon do some pulse response tests as soon as I can get a R134A compressor.
These tests should prove my calculations that instead of just a blown ptc device/and, or damaged start winding, the greatly enhanced transient response of the hard start kit will cause the compressor windings to explode and short to the compressor housing, thus causing an additional fire hazard.
A couple of things I see missing in all these posts. I think I've read all of them,...I need to learn something new each day that I didn't know the day before,...as should everybody else.
1) It has LONG been acknowledged that R134 has it's own set of problems, proven in the automotive industry when they switched over. R134 itself is anything but benign to components in your closed system WHEN COMPARED TO R12. Not necesssarily the refrigerant,..but the impurities they will carry.
Having said that,..and knowing that the big 3 went ahead with it KNOWING that once a unit was opened, there was a VERY good chance it would not make it to 6 months,...vac for 3 minutes or 3 weeks,..they knew it, and later on, everybody else knew they knew it..if they bothered to check.
2) Are appliance companies more benevolent? Are they even about to tell you that if something is "iffy" in a 134 system,...you are going to fail much sooner than an R12 system? I suspect they don't know and don't care. If they even cared ever so slightly about their engineering,,,wouldn't they have a self resetting plug-in fuse in an easy to get to place...rather than calling it an overload and sticking it under the haystack (of course,...that does incrrease employment for techs)? Gee,. something that would not go obsolete???? Isn't that strange,...and I suspect even an aerospace grade one is cheaper than most overload switches. I've never met anyone who could tell me a difference that mattered. Maybe one of you guys can. Overload switches and self-resetting breakers, etc.,..are not something that are covered much in my elec. engineering books.
3) The start kit does not increase your voltage from 110 to a higher voltage, ..which would be required if you wanted to push more current through your windings,......it would need to increase that voltage if you ever expected to win a lawsuit. I believe it keeps your voltage from dropping during startup.Unless something is "sick" in there anyway,...keeping your voltage up equals keeping your current draw where it belongs. Gee....not a bad idea,..unless something is already on it's way out. Then it's neither good nor bad,..it's just on it's way out and you may not know it...and you've spend time and money on a 3 in one finding out.
I did read one post that mentioned that R134 is more efficient than R12. I believe you are probably referring to todays systems as a complete unit,..and not the R12 itself.
I won't even touch that except to say...."if you are only doing it because your government requires it.....you may want to rethink your theory", your chances are pretty poor when the free market didn't think they could make a better unit with something else....until the govt. told them too.
One more thing (I think someone mentioned in one of these posts about start relays themselves), my understanding (I've never took a die grinder and cut one in half to look at,..so this is from reading,..and probably NOT from a textbook,..I don't know where I read it), is that a start relay for a fridge compressor is not a relay like most people think of when you state the term "relay". But more like a fuse that cuts the circuit to the start winding after the "start windings" part of the relay have current through them for a couple seconds.
Gotta go.
