Too hot! Landlords, which is better, attic fan or insulation?

[Vishakha Penney]

We are in the middle of a hot North Carolina summer, and one of our older, C class properties is not cooling properly. 

It is unclear to me at this point if this was an issue before. We've owned this house for nearly 4 years but no previous complaints about too hot or cold. The HVAC is four years new. Previous tenants may have just tolerated it, but I really have no way of knowing. The HVAC people have tried and tried to fix it, and at this point their conclusion is that the unit is now working properly and the final issue is with the house, ie, basically no insulation. 

Now, we do not generally put money into insulating class C rental properties. However, we have to do something as the house will not cool below 80 degrees despite running the HVAC continuously.

The HVAC guy recommended an attic fan because of the very high temps at the ceiling. However, I looked online, and many seemingly knowledgeable people recommend against them, and recommend just doing a lot of attic insulation. 

Its probably going to cost around $800 either way.

Would love to hear your experience on this matter. Thanks!

Some references for those interested:

http://www.homeenergy.org/show/article/year/1995/i...

https://www.energyvanguard.com/blog/38676/Don-t-Le...