Hello,

I hope this post finds everyone well and staying safe.

I have a 99 Ranger XLT 3.0L V6.

AC pressure is testing low and I did some research on this forum and am hoping some kind folks have more knowledge than I do.

First off, is it normal for the AC compressor clutch to stop and start (with a click each time) or does this only happen when the refrigerant is low? This is my first summer with the truck (and I rarely run AC) and I just happened to notice the clicking for the first time and saw that the plate would stop spinning.

Secondly, does this mean that I might have a leak or is it possible over time for the pressure to just get low? Saw a lot of disagreements about this issue.

Also, someone mentioned oil for the compressor? Is this something I should be looking at first? Someone also suggested cleaning the evaporator core and evaporator fins as well? I'd like to do the best I can on my own and don't mind learning but am unsure about where to start.

In any event, I see that it take 134A refrigerant (and am looking at the A/C Pro ACP-100 Ultra synthetic kit with the gauge). I have no idea what's in there now so hoping that synthetic type isn't an issue. I'd really like to do this myself as opposed to paying a shop over $100 bucks and, in the process, do any needed maintenance as referenced above.

Any insight is appreciated!

 

Yes, the compressor clutch will engage and disengage all the time but not quickly on and off

All AC(home or auto) works by compressing the R134A refrigerant to a high pressure which causes it to heat up
Then slowly releasing it into a lower pressure(in evaporator) which cause it to cool rapidly

There is a high pressure switch and a low pressure switch
If the pressure gets too high then compressor shuts off to allow pressure to drop as R134A is released into the low pressure side of system
If pressure gets too low then compressor shuts off because there is not enough R134A in the low side and compressor could "run dry" causing it to burn out

So it can be "normal" for compressor clutch to cycle as pressure changes in the system, i.e. your refrigerator, same system, works the same way, its not "on" all the time it cycles on and off as needed to keep temp stable inside, it has pressure switches as well but just for safety, its cycling is controlled by thermostats

Yes, the pressure will go down over the years
If you have pressure in the system now then it won't have a leak, at least not a big leak, so you can add R134A with a dye and "leak blocker" to the system
The dye will ID a leak if there is one
The Leak block can help seal a small leak in an o-ring

Yes, the R134A has oil in it for the compressor, the compress was filled with oil when it was first installed and the R134A adds a bit more
Compressor do burn out over time, bearings usually, but if it ain't broke don't fix it

An AC service shop would evacuate the system of R134A and then apply vacuum pressure to see if it could hold that pressure for 30min or so, if so then no leaks

 

Thanks for the informative reply, Don. This helps me understand a lot better!

Is the dye and leak blocker a separate product from the refrigerant?

Is it worth cleaning the evaporator core and evaporator fins before adding it?

 

The can of R134A comes with those additives, look at the label, all R134A comes with oil, the other additives are optional, so look at the label

If you evacuate the system to clean evaporator then you must replace other parts because they were exposed to outside air, i.e. receiver/drier and orifice tube/filter
So no, not at this time

After you "top up" the system and it still loses pressure then there is a leak so at that time you would evacuate the system and find the leak and do the cleaning/flushing of parts in the system

To clean the outside of the evaporator you remove the Blower fan in engine bay and reach in to clean any debris out from in front of evaporator