1997 Nissan Maxima 165,000 miles... With an outside temperature of 85 degrees with 70% humidity, A/C low side reads 85 psi and high side reads 125 psi with compressor clutch engaged and A/C blower on high.
With A/C turned off and compressor clutch disengaged readings on both low and high side are 110 psi.
Any thoughts or recommendations on what is possibly the fault in the A/C?

Comments Appreciated

 

Low side pressure being too high and high side pressure being too low is indicative of a failing compressor or a compressor that is not engaging properly.

Have the compressor checked for proper operation.

 

Decided to replace all components in the A/C system... compressor, expansion valve, evaporator core, condenser and drier.

My understanding is to have a repair shop remove the freon first.
Then I will remove and replace all existing components, then have the repair shop pull a vacuum and replace the freon.

Is this the correct procedure? Any other parts I should look at replacing or problems I may encounter?

 

I did the same thing on my 5th gen. I wasn't about to fuss with an old system and I had an opportunity to do the job while the car was down during my engine swap. You're lucky, your evap coil is cake to replace. 5th gen evap coil is a doable but an absolute nightmare to remove and reinstall the air box. Hop on ebay and grab a new, surplus stock, OEM blower fan while you're at it. Think I got mine for $55. Don't forget the cabin air filter. Good opportunity to clean the inside of the air box and replace all o-ring seals too. Throw a new high pressure switch on the condenser while you're at it.

Also, why pay a shop to pull a vacuum when you can buy a vacuum pump on Amazon cheaper than it would cost to have the shop do it?

I used this one, have had it forever. It's pulled down a lot of carbon fiber projects in the past:


Get a loaner set of gauges from AutoZone, a few cans of DuPont 134a and you're set to pull vacuum and charge it up yourself. You could probably have it done in an afternoon because your airbox is so easy to remove.

134a has zero negative Ozone effect. Just sayin.

 

I saw you have some humidity, so do I! Tampa, here.

Most T&P charts don't account for it, so here's a good chart as it includes RH, just in case you decide to charge it yourself. Kind of an important factor to consider in such a wet climate.