Old 01-12-2008, 06:57 AM
Senior Member
Join Date: Feb 2007
Posts: 18,196
Default Re: Mis-matching HVAC system (replacing outside unit without touching inside)

I had a similar problem on a 10 year old Trane unit - the compressor seized up from what I believe was a lightening strike. I had the original installer and one other tech come out to diagnose the unit and provide an estimate. They both initially recommended replacing both the inside the house blower unit and the entire outside unit, not because there was anything wrong with the inside unit, but because they said it would be impossible to match up the ratings of a new outside unit with the older inside unit.

While I am sure there is some truth to that, I got the sense I was getting a snow job. I did a little research, and found out that the tolerances were not so precise that a "closest match" would cause risk of premature failure or any material inefficiency. Certainly not to the extent where I would be willing to put in a whole new system. Watch out for that scam. This is the equivalent to the brakes guys selling you new calipers with a basic pad replacement. I am sure we will hear from the HVAC guys who will come on and defend their turf.

I ended up calling a third tech, and told him to replace the compressor, which he did. Part - $600, labor/refrigerant - $400, and it has been running fine for the last 7 years.

The blower motors have a long life. If the coils and piping are still in reasonably good shape, I would just replace the compressor. They are the weak link in the system, so you could easily be in the situation again in 5 years.

joenew61 is offline