Low refrigerant?
 

The A/C in my truck(1993 F-250) only blows 60* at idle, but will cool down to 45* while driving. Could this be due to a low R-12 level or is something else going out?

I'm thinking fan clutch but to really check your system you need to put gauges on it.

+1 on the fan clutch. Classic symptoms.

The fan clutch? You mean the airflow through the condenser would make that big a difference? The engine doesn't run any hotter at idle. I'll check it out though. I'll admit to knowing nothing about A/C other than the names of most of the components. :D

Yep. Your AC performance at idle/low speed will suffer long before the engine is effected. The fan clutch is actually a wear item and should be replaced every 5-8 years, but nobody ever does. At 16 years, I guarantee yours is weak.
BTW, don't go cheap on the clutch. The ones from the "chain" parts stores are often not much better than your worn OE unit. Get a Motorcraft replacement or Hayden HD or SD unit. It's going to smart a bit on your diesel. I believe the MC clutches are close to $200 for oil burners. Check with one of the site sponsors.

I can get a Hayden SD for about $120, thats not too bad. I'll check it out tomorrow when I'm working on the truck.

Not sure if the fan clutch is bad as it feels pretty tight in regards to spinning, but the water pump was. Plenty of play in the shaft. While replacing that I noticed the radiator was full of crap so now it's getting cleaned. One thing leads to another.

The list continues, radiator can't be cleaned, dimpled core tubes. I got the new pump and new radiator in and was able to confirm the fan clutch is bad as well. I'll replace that tommorrow, making this one of the most expensive questions I've ever asked.
$80-Coolant
$350-Radiator
$25-water pump
$25-new hoses
$120-fan clutch
=$600.

Then stop asking questions and turn up the radio, fer cryin' out loud. It's much cheaper that way. Just ask my Ex-Wife. :-X04:-X04:-X04
Sorry, I just had to go there.

That amount is just what you run in to on a 17 YO, used vehicle that hasn't been maintained strictly "by the book" since Day 1. Most vehicles aren't. Even then there are problems once you look a bit deeper than the surface. Mechanical things just wear out, deteriorate and get used up over time. At 17 years, your truck was WAY past due if all of those parts were even close to original.
Compare that cost to a new truck payment, over the next 6 months.

Consider this: By 1980, a large percentage of ~1963 Ford PUs were scrapped because they were plain worn out by then. I remember 1980 very well, and rarely saw a ~63 Ford pickup.
In contrast, in 2009 there are still tons of ~1993 Ford PUs on the road. Even in My area of the rust belt you can't swing a dead cat without hitting 2 or 3 of them.
30 years ago, your 17 YO truck would have likely been long in the scrap yard.

No kidding, hopefully I've got it all covered for awhile. Coolant is so expensive for a diesel that I didn't want to have to drain it again for a long time, especially since it has a service life of 150k miles. The $80 I paid for 8 gallons was a steal since the guys sold it to me at cost instead of the original $17.50 a gallon. Still, I prefer the nickel and dime stuff as opposed to the monthly payment. We'll see if this fixes my A/C problem though, since the wife wont be letting me spend any more money for awhile.:-D