82 300CD air conditioning repair
 

Thinking about how cool I could be driving my old classic around, I had the AC looked at the other day. Verdict was new drier and condenser and refill. However, I'm trying to avoid the expense of Freon.

I searched the archives and found a little bit of information but not a lot from people who have actually done a conversion themselves. Can anyone please describe their experiences with using either Freeze-12 or R134? Pros? Cons?

I have a new drier and seals on order and am just looking for any information to help me decide what to refill my AC with.

Thanks.

RE: 82 300CD air conditioning repair
 

r-12= money. my 300sd blows ice cubes on 134.

RE: 82 300CD air conditioning repair
 

Pats300sd,

Did you do the conversion yourself or have it done? What was your experience?

RE: 82 300CD air conditioning repair
 

prior owner had it converted to 134. if yours is r-12, it's your call. expansion valve needs to replaced / cleaned anytime system is opened. old hoses deteriorate from the inside.
key is a/c mechanic who knows what he is doing. most a/c guys cringe at the prospect of
working on m-b systems.

RE: 82 300CD air conditioning repair
 

I don't know why anyone would cringe over it. It does not seem even that different from the GM system in my old truck.

Again, does anyone have any experience doing this job themselves?

RE: 82 300CD air conditioning repair
 

the expansion valve is the fun part.

RE: 82 300CD air conditioning repair
 

The dessicant in your drier is not rated for R134a and will liquefy over time eventually causing your compressor to seize. Also, it is difficult (almost impossible) to get all of the R12 compatible lubricant out of the system before adding R134a and the new lubricant into the system. Best option is to go with a R12 compatible non-R134a refrigerant such as Autofrost or Envirosafe. These can mix with any remaining R12 in the system and are fully compatible with R12 lubricant. Plus, you don't have to change over any of the o-rings or hi-side/lo-side fittings. Stay away from those R134a conversion kits - it will cost you $$ in the long run.

RE: 82 300CD air conditioning repair
 

Thanks Drrty240D. Did you do this yourself?

I have a new Behr drier to install, along with new lines, seals, expansion valve, etc. Would that still be harmed by R134?

My local dealer converts cars to R134 and claims no problems. I have everything to do the R134 conversion but mostly because I bought it to put in my truck. At this point, I can just as easily go with an R12 compatible.

pats300sd - have you changed the expansion valve yourself (your earlier posts seem to indicate you didn't)? what's so 'fun' about it?

RE: 82 300CD air conditioning repair
 

And here's the after-action report:

This was moronically simple. I changed the drier, two of the hoses, the aux fan switch (new hi/lo pressure switch), and the expansion valve. The system was already empty so I didn't have to worry about R-12 recovery. Someone had commented that the expansion valve was a bugger. That couldn't have been farther from the truth. The passenger side panel removes with three screws and two plastic clips and the expansion valve was right there next to the blower motor. It was a simple swap from there.

I did notice that the valve I took out was already a replacement and was marked that it was for R134a. Considering this, that made my decision on which refridgerant to use very easy. One new low side valve, a can of oil, a can of red dye/sealer and three cans of refridgerant later and my ac blows ice cold. Total cost (minus the diagnostics my local specialty shop did) was less than $200. Total time was less than 3 hours.

RE: 82 300CD air conditioning repair
 

congradulations, you pastthe test.