If your system is in need of replacement I am guess that it  is about 10-15 years old. That means it started off as SEER unit. It will lose some  SEER over time and the codes were nowhere near as strict back then as now for  tight installations. Our surveys (the $39 coupon one on this page) have shown  that the average older system has an effective SEER rating of about 6. So take  your monthly electrical in a month that you operate your air conditioner,  July-August, and subtract a month that you don’t use your home air conditioner,  March-April. That number is the approximate amount of your air conditioning  usage.
 The service today was excellent!
The service today was excellent! 
 I appreciate his attitude in doing this correctly and with  quality workmanship.
I appreciate his attitude in doing this correctly and with  quality workmanship. 
 They were polite and very nice. Thank you again for all the  work they did for us.
They were polite and very nice. Thank you again for all the  work they did for us.
          For 13 SEER (minimum) multiple  that number by 0.46 (6÷13). Your bill is just under ½ of your current bill.
          For 20 SEER multiple that number by 0.3 (6÷20). Your bill is  less than 30% of your current bill.
Why you should have your air conditioner tuned up every year.
The Benefits of Planned Air Conditioning Maintenance from ACCA
AccuClean Whole Home Air Filtration System
IQAir16 - Whole House Air Filtration System