Average cost to update A/C?

My '93 Dakota still has its original R12 system. The compressor kicks on when A/C or defrost is selected, but, its not cold.

What's the average cost to convert over to 134? (assuming there is no major parts replacement). What all is involved?

I checked around when I first got the truck and prices were all over the place. At the time I decided to wait until I knew the truck didn't have any (major) mechanical issues.

The heat isn't as brutal as it was in my wagon, so, I've been living with it. Now that I know I want to keep the truck, I want to get the A/C working.

Aside from pricing, any other sage words of advice?

Thanks.

i have a 92 dakota with the v6 magnum,when i changed mine over i just added the correct oil and fitting adapters,i also replaced the filter drier and the expansion valve and one bad return hose,drew a vacuum and charged it with 134a,no leaks and it blows cold,most people think you have to replace all the o rings,etc,i just put fresh o rings/seals where i had it apart,i DID NOT drain out the old oil from the compressor

Why not just top off the R-12? Every system leaks down with time and the R-134 will leak faster.

Because I don't have the means to do it myself, and the few shops I found willing to do it, for the cost, I might as well convert.

Go to the local auto parts store and buy a low side 134a fitting, screw it on and buy one can of 134 with a charge hose, turn the a/c on and charge it. U don't need to change anything but that low side fitting. Your system still has a sight glass on the drier, when the bubbles are gone it full. I do this all the time and have never had an issue. If the compressor is coming on it's not very low on Freon.

Freeze 12 (no butane) works well and you can use the existing ports with a cheap can tap charge hose.

I am with kenworth. I used to buy into the hype about you can't mix or swap them but I saw soooo many people doing it with no ill effect I say just go for it.

A "full tilt boogie" changeover is expensive. Receiver/dryer, hoses, flush, expansion valve maybe high capacity condenser. $1,000+. Personally, I would try the freeze 12 or add a can of 134 first.

I still have some R134a left I bought for my van. I may just give it a shot (no pun intended).

Aside from seals, is there any real difference between an R12 compressor and a R134 compressor? I was looking on RockAuto at compressor prices, and for my year truck, the compressor is about $300. But, go up two years, (same body style) and a R134 system, and the compressor is less than $200.

Thanks guys.

Groan.