My 1992 subzero refrig (Model 501R) has ice building up on the back wall. We defrosted once but the ice came back. Just had a service call and the estimate is $1400+ tax to replace the evaporator coil and the temp. control switch. Is this cost reasonable and does it make sense versus buying a new one?

Not worth it. One reason repair is so expensive is that the refrigerant used is R12. The only R12 that is available today is what has been reclaimed. At one time you could buy a 30 lb can of R12 for less than $70. Last time I looked it was $1000 and that was a long time ago. My understanding is that today it cost about $5000.

I had to replace my old Subzero about two years ago. Replace it with a GE built in. The old Subzeros were not very energy efficient. Think the GE was about $6000. Still have to make the door panels for it.

You are being ripped off. The only thing wrong with it is that you need to replace the defrost timer, heater, and terminator. This will cost about $50 or so. The only thing that will cause this is a failure to defrost. You can easily fix it yourself. He is taking you for a real sucker.