I was under the impression that lots of folks have slow leaks and have to top off every season.

I have only had the car a year, and it was off road since 05 at least before that, so i dont know how fast/big the leak is. I didnt want to test it with r-12.

I also thought that if I didnt need to open up the system i didnt need to replace the drier and expansion valve.

I was also under the impression that the r12 oil and the 134a oil could be happy in the system together without having adverse affect on one another.

I could very certainly be wrong about some or all of the information above.

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1996 E300 110,000
1985 300TD 212,000
1980 300D 238,000

You don't know if you have a slow leak or a big leak.

I don't blame you. But again you can't simply 'drop' r134a in to an r12 system and expect it to work...at least for any length of time if there are already problems with your system.

You will most likely have to open the system up anyways.

There is oil that is compatible with both r12 and r134a. The problem is you don't know what oil is in your system. More importantly you don't know how much is in your system.

That is why you need to do some reading... Have fun! I found the most useful information on this forum.
http://www.autoacforum.com/messageview.cfm?catid=20&threadid=7927

It is legal to top up a leaky system, but only after attempting and failing to find the leaks.
This is normally true, but if your dryer is original, it is incompatible with 134a.
No, this is certainly wrong. The mineral oil for R12 will not migrate properly and can cause problems.

most shops have nitrogen cyllinders that they can pressurize your system with for a couple bucks... let them, then go around with bubbles and look for leaks. have them pump it up to 200Lbs... that ought to show you where the leaks are.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

UPDATE:
I called Harbor Frieght yesterday to check on my order. It seems the vacuum pump is on backorder until July 11th. I wish they could have told me this. So I cancelled the order and started looking for another one.

I did a quick search and found this one:
http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=MAS90062-A

When looking at the phone number to call them I saw it was my local area code. So I called and asked them if I could pick it up in person to which they said of course.

So now I have a vacuum pump less shipping charges for just a few dollars more than the one from HF. I got it for 106.25 + taxes as I am a MN resident.

I took it out of the packaging and everything looked great. I'm going to go evac the system right now and will report back.
-Ryan

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Let us know how long it takes to pull a vacumm, I have the cheap harborfriehgt venturi pump and its works pretty quick, but doesn't pull the "deepest" vacuum possible.

For those of you who are handy, you can make a dandy vacuum pump in your garage....




I've been using a refrigerator compressor for 25 years. On my first one, I silver soldered the 1/4" flare connections on and it lasted over 20 years.

I recently built another, using a new compressor I found on eBay from a freezer that had been damaged. I think it cost me around $35.

This time I JB Weld'ed the fittings on the line, installed a line and plug, and viola!, another great vacuum pump.

I've also rigged up an R12 recycler, using a couple of inline filters and an old propane tank, in concert with the vacuum pump.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

It was quick. For sure under a minute, possibly even under 15 secs.

I have a venturi pump as well (got it for like $7 over the winter) but decided not to go with it.

This pump pulled all the way down so the needle bottomed out on my gauges.

You will not be happy long term with a 134 "conversion". Unless the climate in your area sees temps no higher than the mid 80's and low humidity. The R12 systems were not built to be used with 134 and they perform and deteriorate accordingly when used with 134.

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.