Do you have an attic space, and if so, what kind of insulation do you have up there? You may need additional insulation blown in to inhibit heat radiating from the attic through the ceiling.

If the ceiling feels warm, you definitely need additional insulation or better attic ventilation.

I had the attic/crawl space re-insulated last summer.

If the HVAC tech finds the a/c working properly, he should be able to check and see why it isn't cooling the home and he should know what to look for.
*Infiltration- leaks around doors, windows, cracks, ect.
*Poor attic insulation, wall insulation.
*Added on rooms to the home.
*A once light colored roof was replaced with a dark colored roof.
*More appliances running in the home and/or traffic.
*Lost a huge shade tree, and the ones doing the heat load on the home made the mistake of including that shade in the load.
**Most of all- check the ducting for good insulation and air leaks!! Make sure a return duct has not opened and is sucking in hot attic air.
A second opinion, if your a/c company can't or won't help is always a good idea.

Thanks........I have a HVAC tech coming out this afternoon.
The previous owner had a furnace, evap cooler, and flex ducting put in the house some 7-8 years ago. They took the path of least resistance in every way. For example, they put the intake on the lower inside garage wall right next to my wood burning stove so in the winter if the furnace kicks on it would suck the smoke right out of the wood burning stove. I keep the damper shut now. Always wondered about the duct work. Also, wouldn't the air coming out of the vents be below normal if warmer air was being sucked into the system? Thanks....I'll post again after the tech gets here.

OK, the jist of what the HVAC tech found are
1) the air ducts in every room are far away the outer walls of the house instead of near the outer walls and blowing on them.
2) bad location of the thermostat.
3) bad location of the intake.
4) low R rating of flex ducting.
5) 6 inch diameter flex hose to bedrooms.
Basically he said the ducting needs to be replaced and move the thermostat and intake. He also said the system seems to be somewhat restricted probably because of the ducting. Will get an estimate Mon or Tue.

I guess my only comment would be that since this HVAC tech has suggested a fairly radical alteration to your existing system -- you might want to seek out one or two other assessments of your cooling dilemma. If there's some consensus, then you're probably on the right track.

Otherwise, you might want to carefully consider before investing a significant sum in the opinion of a single technician -- Unless, of course, he's willing to guarantee the solution.

A second opinion or 2 would be a very good idea. We had to do a number of things to get our system working right (by "right" I mean being able to maintain 75° in 100°+ weather without the system "struggling" to do so): additional return air, new windows and attic ventilation. We also did some work on the system similar to what you listed above but that alone didn't fix ours (similar problem: inadequate cooling when outside temps reached or exceeded the mid 90s). Correcting the items you listed may not be enough to fix the problem, although every house is different. Maybe in your case it would work. I'm not an HVAC expert, I'm just relating my experiences as a regular user with a similar situation...

Thanks. More info.....just had a HVAC tech here today for a quote to hopefully "fix" the problems. First he said to go with the cheapest things first....that I liked. My duct system is flex with two "director"? boxes. The sheet metal boxes themselves are not insulated at all and there are leaks where the corners are pinched together. There is also nothing sealing the flex venting to the director boxes. Just tabs.....some of which are not inside the box. He suggested sealing all the venting and putting another intake in the ceiling of the hallway and re-locating the thermostat to the hallway (the thermostat is now in a part of the living room near a outside wall not even close to the current intake). All this for the low price of.....$3,000. Right?

Arizona:

Can you seal the leaks yourself?

The leaks should be fixed. You can probably diy if you wanted to.

Be sure that if they add return air that it's done in a way that doesn't cause things to get really noisy. The first time they did that here they just opened up the side of the furnace blower to the hallway. Yes, I got great return air, but it sounded like a 747 taking off when it was on. They just couldn't understand why that wasn't OK just outside our bedroom. We closed that off and ran the extra return through a closet area with a short run of flex and that worked very well.

My installers also did that "move the t-stat" trick with our t-stat at one point and it made things much worse. I'd recommend if you really want to try that, just tack on some wiring to the existing wiring, run that to where you think you want the t-stat to be, hang it on the wall and try it. That way if it doesn't work you haven't gone to all the expense of having it moved over just to have to move it back to where it was originally. Ours is back in the original spot btw.

Everything you are going through sounds just like what I went through. Real deja-vu. In my case it looks like my main problem was the heat load in the attic. If your attic gets *really* hot in the summer (mine did...so hot the wood up there was sweating sap) you'll probably want to vent it. We used powered roof mounted units that have really done the trick. If it gets that hot insulation alone will not help enough. The next best thing we did was new low-e double pane windows.

We just added a Black metal roof to my home which once was aluminum siding & now is masonry home. We did one thing in my attic to GUARANTEE that my attic wouldn't be more than 100 degrees on the hottest of days. My home is single story, 3,000 sq ft ranch w/ partial basement Rheem 3.5 ton R-22 system.

We put in Radiant Guard Barrier Insulation in attic & envelope of our home.We used their 'Ultra product' just rolled out underneath the rafter ties and stapled with 3 inches of space between the Ultra roll & the plywood sheet. With there being only a roof vent in my home now of 22 sq of roofing & passive soffit venting I had to do something prudent. Now I reflect most of that energy out of my attic. Have a cousin who has 3 story home in Houston,Texas & he swears by this product. Believe me it works..so does power venting if you have a gable roof.

As for your estimate I would get a 2nd opinion & get the metal foil tape ($15 a roll from Lowe's or HD) and I would seal those leaks for way cheaper than paying 3 grand. I paid less (1/2) than that for this product and I have no problems

Here is a link that might be useful: Radiant Guard

You got a lot of good advice.
The first placeto look is the heat-gain radiant heat & air infiltration.

If you want to do some studying concerning the AC System, you can begin by using the link provided. udarrell _ 2007

Here is a link that might be useful: udarrell.com

woodinvirginia... What is the emissivity of your metal roof to begin with? I suspect that it is the major factor in the reduced attic temp, and that the RB does not add much more. And don't forget that it throws off heat at night a lot faster than asphalt shingles -- which are a heat sink on your roof compared to metal.

For example, our metal roof has a factory-rated emissivity of 89%, so an RB in our case is not worth spending $$ on foil and my climbing into the attic.

arizonared... In our old house I spent a couple of hours with metal tape and caulk and sealed everything. It made a huge difference.

The temp difference between intake and output should be between 18 and 23 degrees. At least thats what my Rheem puts out. I would say the unit is undersized. I can keep my poorly insulated home at a comfortable 70F (colder if I really want it) on a 90F plus hot and humid day here in Ohio and the unit maintains and cycles normally. For 3 grand sounds like someone is handing you a line unless your 1985 built home is really constructed that badly. That would be hard to swallow. No amount of insulation or sealing is going to drop the indoor temp that significant of an amount. If they have told you the temperature of the unit at the registers is normal, then your ducts cant be losing that much. I do however question the return being in the garage sucking in uncondtioned air? That to me seems to be the problem. Perhaps it's simply not moving enough air? Attic ventilation always helps! HVAC techs are a dime a dozen and some hungier than others. Get as many professional opinions as possible.

My response to preceding post:
Rheem may state those figures, however, very high humidity levels will drop most unit temp-splits below 18-F.

Example: 1) 80-F dry bulb (db) & 67-F wet bulb (wb) "Temp-split 18.3-F."
2)76-F db 69-F wb "14.3-F temp-split," a high humidity.

A link below for Ductwork design thoughts.

Here is a link that might be useful: udarrell.com

These are not Rheem quoted figures, there actual dry bulb. Although I am sure there are number of variables that effect the outcome. Type of evaporator coil design piston vs capillary, load, geographic location, etc. 18 - 23F dry bulb is a good safe reference. My system works quite nicely and Rheem turned out to be a good choice.