Upstairs A/C unit not cooling in high temp

I've got a dual-zone system in my two story home. The upstairs A/C does not keep the upstairs cool at high outdoor temperatures (say above 85 deg). However below that it does okay. I've had the repairman out to re-fill the freon the last couple of springs, and this year it didn't last all the way through the summer. Apparently I have a leak somewhere, just don't know where.
One possible clue... last week during mi-day I went up in my attic (where the upstairs furnace/blower is located). Even with temperatures 85+ deg outside, the attic was not as hot as I would have expected. Could the cold air be "leaking" into the attic somehow?
The outside A/C compressors are Trane mfg.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
DesignGuy wrote:

It could also be, "a leak in the return air drawing in hot attic air through the evaporator." Have an energy audit done on your home and fix everything that will reduce the load. -Darrell - udarrell
--
Crank Your Air-Conditioner Up To Specs
http://www.udarrell.com/air-conditioner-capacity-seer.html
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
udarrell wrote:

temp coming out of AC register should be about 16-18 degrees cooler than temp in room.
paul
--



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

This is Turtle.
If you say you have to have your hvac system refilled with freon every spring and it is becoming fall now. Me think your running out of freon early before winter sets in this year.
Also have the HVAC fellow who fills your system to find the leak and fix it.
TURTLE
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.