I know nothing about them but will share my experience.
Mine was dead, the compressor was shot as well as the contacts. I had a company come out last year, they gave me an estimate of $1700 to fix and $2100 to replace.
Had another company come out this year, wanted to replace the entire unit, it's foundation, it's fuse box, the lines, and something inside the house (don't remember the name). They wanted $5002.
A friend of a friend has been doing hvac work for 30 years, he fixed it for $1200.
I said all of that to say make sure it has to be replaced before spending $4000.