Heating, Air Conditioning, Fridge, HVAC/Central AC Freeze Up


I have a Lennox central AC that is probably over 30 years old.  It has frozen up before and replacing the filter has always solved the problem.  It froze up again yesterday, so I decided to clean the evaporator coil (I've never done this in the 20 years I've lived here), I changed the filter and I cleaned off the outside unit (It had quite a bit of build up on it).  

The unit seems to be working ok now, with better air flow.  If all of the cleaning didn't work and there's a bigger problem, do you have any idea how long it will take for it to freeze up again?  I guess I'm just wondering when I can consider myself in the clear for having to make a service call :)

Thanks so much for any insight you can give.


Hi Susan, Sorry it took so long to get back to you. I would say you are in the clear. If you change the filter every two month's and wash off the outside coil once a year it shouldn't freeze up again.

The only other way it will freeze up is if the system develops's a leak.


Heating, Air Conditioning, Fridge, HVAC

All Answers

Answers by Expert:

Ask Experts


Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

©2016 About.com. All rights reserved.