Any thoughts on what it could be? The AC has always been kind of weak as long as I have owned the truck (approx. 2.5 years). By weak, I mean it's just not as cold as my other vehicles. The fan works fine. The air is cool, but not cold. At one time I bought one of those re-charge kits, but the system registered full, so it apparently did not need a charge. The only other symptom I notice besides the weak output is that sometimes at a stoplight (engine at idle) it appears to stop working completely and blows hot air, but then it will start working again when the rpms pick up. Thoughts?

 

What year Ranger?

How much do you know about AC systems?
They are not that complicated but there is specific knowledge required to diagnose a problem.

" At one time I bought one of those re-charge kits, but the system registered full....."
What was the "full" pressure and what was the outside temperature at the time?
AC pressure chart here: http://acprocold.com/wp-content/uplo...rt-33776F1.jpg
Outside temp matters ALOT

If AC Compressor is shutting off at idle(air blows hot), then a pressure switch is opening

Reasons could just be low refrigerant level, or could be receiver/drier or a blockage somewhere.

This is one of those things that you probably need to take to someone that knows AC, it will save you money in the long run.
There are "mobile AC" guys, less overhead so often cheaper than AC shop
Ask local auto parts counter guys if they know of a good "AC guy", many "shop" guys do AC work on the weekends or after 5 for cash, much cheaper than a shop

 

Truck is a 99, 2.5 litre 2 wheel drive.

 

OK thanks! My mechanical skills are good from decades of motorcycle work, but I know nothing of AC systems. Probably best to take it to a pro. This site has saved me so much money (e.g., timing belt most recently) it won't be bad spending some money to have someone else do the work!

P.S. When I did the pressure check I don't remember the specifics, but I did explicitly follow the directions with regard to outdoor temperature and everything else.

 

An AC pro will diagnose the system and then if there are parts that need changing YOU can buy the parts and do the wrench work, then take it back in for recharging.
AC guy will drain the system after diagnosing the problem so you can do the parts swap

If you drain the system you should always install a new accumulator/drier, $30, and orifice tube, $10