Additional info:

My system is electric with the inside unit located in the non climate controlled attic along with the majority of the duct work, no filter up there. The exterior unit is outside approx 30 feet away. The filter is in the return duct in the hallway ceiling with another smaller 1 sq. ft return filter in the upstairs hallway.

Is there an advantage for my specific situation / application of using a pleated filter over the flat multi layer (Dupont 20" x 25" Carbon Air Filter) filter I am currently using.

It still sounds if you have a leak. Leaks need to be located and repaired if possible. The problem is finding a good company and tech who will use standard practices to locate and make the repair. Sometimes repairs can not be made or it's simply not economical to make the repair based on age of system.

How much have you spent the past year to keep unit running?

Your question on filters has little to nothing to do with your problem. I prefer the pleated models MERV 8 that can be purchased at the big box stores.

IMO

Hello tigerdunes,

Thank you for the prompt reply.

I agree with the leak theory, yet can't imagine why / how it hasn't leaked more in the past two years since the freon was last added.

The first thing every repairman does upon arriving is to check the pressure and only one has added freon.

Could I possibly be on to something with the pressure switch being bad / weak?

Is this something I can change without it draining the freon?

I can get parts from our local Granger or a couple of different AC supply houses.

They have quoted me ridiculously low prices for the start kits I have paid several hundred dollars to be replaced.....

I know they also charge for their time, experience, etc, but if I have the ability to change a capacitor, I prefer to do it myself when I can.

As for the amount spent...... I'd have to estimate about $400 or less over the past 2-3 years.

With the unit only being 10-12 years old, I hate to replace it prematurely just to get the new style system as a couple of companies have eagerly offered.

If you lived in a cool climate I would recommend you hold off on a new unit for awhile if possible and fix the leak. There is some new technology that really allows heat pumps to operate more efficiently at much colder temps.. like in the teens which I doubt you will ever see. The extra cost of this new technology isn't worth it in your case.

I would get some quotes and knock the numbers around and get a manual J.

Tiger has the best specs to look for in a system.

I would get the closest matches to his efficiency and option ratings and post model numbers and any other available info in here so it can be evaluated.

for a new HP system

You should replace everything both inside air handler and outside condenser.

these are the minimum specs you should be looking for.
both outside and inside units should be replaced to have a properly matched system.

15 SEER, 12.5+ EER, 9 HSPF
best matching VS air handler
full BTUs in both cooling and heating for your rated size
R-410a refrigerant(same as Puron)
scroll compressor preferred
electronic demand defrost preferred
thermostat with "dehumidify on demand" feature
staged backup heat strips
new and correctly sized refrigerant lineset
10 yr warranty on parts and compressor

you want a thorough inspection of your ductwork system. size, overall condition, supply and return lines, insulation qualities, leak test, etc.

any hot/cold spot issues in your home should be addressed.

My personal recommendation is Trane/AmStd, Rudd/Rheem, and Carrier/Bryant.

Depending on your location, I would not purchase a new system that did not have electronic demand defrost.

IMO

assuming that there is not a leak which is totally possible because no other techs have added freon, and adding a pound could be just a way to add a buck to the bill, you may have an internall problem like a clogged orifice or moisture in the system or low airflow. It sounds as though you need a more thorough troubleshoot from a qualified tech.

Good suggestion by heatseeker

I'm also having a problem with your tech's competence.

IMO

Thank you for all of the replies.

I have more of a problem with the integrity some of the techs than with their competence. Each time they presented me with the bill, the air was blowing cold... The fact that it didn't last tells me they didn't dig deep enough to find the underlying problem- opting instead for a quick fix. This is specifically directed toward the one who added the supplemental start kit to overcome the problem with the faulty exterior fan motor.

I agree with the need for some more in depth investigation to determine if there is in fact a leak or if the pressure switch is malfunctioning- or both.

I'm hoping the problem can be located and 'patched' until I can afford to do the full replacement using the recommended specs provided.

Due to the approaching empty nest syndrome, we're planning on selling and downsizing which may be a good time for the work to be done.

While we sometimes experience a few nights in the upper teens, we can live with extra blankets when needed.

Thanks again and I'll monitor the replies in the event any other ideas are given for where to look for problems.