heat pump cooling Question

We live in Phoenix AZ, so it is critical to be able to cool your home. We just purchased a home that was built in 1997, I anticipate the heat pump on the roof was installed the same year. All the specs on the external plate for the heat pump are gone, no way to tell what the unit is.

It seems like its just not pushing enough air through to cool the home sufficiently.

1) Is there a relatively inexpensive way to increase the power or the push of air through the home? Or something I should check to see if the flow is being obstructed or something? I am looking for any thoughts on this.

I know its hot here but my other larger homes have not had the unit run all day (diff types of units, not heat pumps), but it seems like the unit runs all day and it just struggles to cool the house down, without cooling the other end of the home off (air just does not make it down there with any force). The house is only 1600 sqft so I would think most units the size that is on my roof would be able to handle it.

I am looking for a relatively inexpensive way to fix my problem.

Thoughts?

Yes I have changed the filter.

 

I would check the duct work for leaks or restrictions, see if there are dampers in the system that you can adjust.