R12 to R134A - Page 2 - PeachParts Mercedes-Benz Forum

Kestas · #16 10-21-2003, 08:51 AM

Quote:

Originally posted by Habanero
I am not trying to stir up what seem to be heated opinions (pardon the pun), but I have always worried about the safety of flammable refrigerants in a diesel vehicle. There probably isn't enough refrigerant in the system to worry about, but I always wondered if a catastrophic leak would create a runaway engine scenario. I have heard of caterpillars hitting propane lines which fed the engine too much fuel, thus blowing the engine. Anybody think this would be a valid worry on our vehicles?

It would have to be a catastrophic and perfect scenario. I'm more worried about the 20 gallons of flammable fuel in the tank than the 12 ounces of flammable refrigerant under the hood.

#17 10-21-2003, 08:54 AM

Your A/C system was not designed to run 134a. Higher pressures will cause premature failure of everything in the system. If never converted stick with r-12. If converted to 134a and you want to go to a gas that is very close to r12 performance use duracool. (cheap way to get rid of 134a) As for duracool causing a runaway engine I find that pretty hard to believe. A 300d charged with duracool has a whole 12 OUNCES of gas. If a hose broke and all 12 ounces was sucked into the intake you may get a boost but I don't think you would even notice the extra power as this 12 ounces would also be mixed with outside air and most would not even make it to the intake.

Habanero · #18 10-21-2003, 10:27 AM

I wasn't sure how much volume the a/c system contained. 12 fluid ounces surely would not be too much of an issue unless, like Kestas said, it would have to be the perfect scenario. I am completely sure, however, the 20 gallons of fuel behind me are not going to blow the engine (unless I use them up much too fast

). Anyway, thanks for the opinions.

tjohn · #19 10-21-2003, 10:41 AM

Quote:

Originally posted by rebootit
A 300d charged with duracool has a whole 12 OUNCES of gas. If a hose broke and all 12 ounces was sucked into the intake you may get a boost but I don't think you would even notice the extra power as this 12 ounces would also be mixed with outside air and most would not even make it to the intake.

It's at least been reported as happening. See this thread http://www.peachparts.com/shopforum/showthread.php?threadid=62914

leathermang · #20 10-21-2003, 10:46 AM

"I'm more worried about the 20 gallons of flammable fuel in the tank than the 12 ounces of flammable refrigerant under the hood."

This statement has been made in a general form by more than one member...

It ignores some very obvious facts.....

1. The fuel in the tank is intentionally protected by several measures including placement, type of steel used to secure it, forming of the sheetmetal , seam integrity, etc...

The placement usually means that another steel structure has to be breached significantly before there is any chance of the fuel tank being breached.

2. A simple spark near diesel fuel will seldom ignite it.

3. A simple spark in the area of something like propane mixed with air usually does ignite it.

4. Most collisions involve the front of the car.

5. The area which holds the Duracool or other similar types of gases is at the VERY FRONT of the vehicle and has no particular protection built into the car to attempt to keep it from being breached. Usually all that is in front of the condensor is a ( now ) plastic grill.

6. The addition of a combustable gas which would be more easily ignited than diesel and in an area which would be prone to sparking in an accident increases the chance than any diesel spilled in the accident would be ignited.

7. This situation is easily avoidable... and I think this is why some 17 states have made these types of refrigerants illegal....

8. R-12 is available now and systems can be flushed and this reinstalled. The info about system pressures being higher with 134a than they were designed for seems to be true.... and seems to result in a significant reduction in the life of the compressors.

gsxr · #21 10-21-2003, 11:37 AM

Cracker, that quote almost sounds low - at least for the compressor. Maybe not though, since they don't need to open up anything else. Hmmm. The only Nippondenso rebuilds that don't blow up within 2-3 years are the Nippondenso factory rebuilds, and the Mercedes dealer rebuilds. Anything else is false economy, IMO. Smart move to stay with R-12, btw. Look at the big manifold hose. If it is wet at all, it MUST be replaced - they leak through the barrier, the wetness is refrigerant oil. Costs about $100 to have your old hose rebuilt (don't buy new, they're $300-$400) but labor to R&R will be 2-4 hours!

Side ACC tip: Pull the glovebox and test all seven of the vacuum lines for the ACC pods with a Mity-Vac. They should all hold vacuum. If not, one or more is bad. If they're not working properly, you may not get proper airflow or cooling, or no recird function (which is essential in hot areas). A photo of where to test is here:

http://www.meimann.com/images/mercedes/W124_dash/manifold_defrost.jpg

Habanero, about the flammability issue. Have you ever looked at the MSDS for R-134a? It's also highly flammable. The probability of having any serious accident from a runaway engine or refrigerant explosion is, IMO, up there with winning the lottery or getting hit by lightning. For the record I strongly recommend staying with R-12, it DOES NOT cost much more money, unless you are getting screwed by a shop that gouges on the price and lies to customers. It's $20/lb on eBay and other places. Fifty bucks ain't that much to pay to stick with something that WORKS and won't blow up.

cracker928 · #22 10-21-2003, 12:09 PM

Well, thank to all for the input! Some have given me some feedback indicating it is a good DIY job, but I don't know if I have the time for that. I will stick with r12, and at least I won't feel ripped off if I go with the quote I mentioned.

This does make me appreciate my slow '93 that much more...

-Neil