The best advice I can give you is to find a reputable A/C shop in your area via recommendations. Unfortunately, most of those "gages" on R134a cans are not suitable for this due to limited accuracy. It's sort of like checking your kid for a fever with an oven thermometer.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Makes sense. One other question, the a/c line that runs across the top of th e engine doesn't have any insulation. I felt it and it felt slightly cold, but I can't help but think that all the heat from the engine compartment would have some adverse affect on that line. I read in another thread that you can buy pipe insulation a tie-wrap it to that line. For example, the oil filler cap was so hot, that I couldn't even touch it and this line sits right up against the valve cover. Do you guys think this would help at all? I am pinching pennies right now so I really can't afford to take it in to a shop at the moment.

Help, yes. Solve your problem? No.

but I think it is more like checking your kids temperature with a aquarium temp strip. it gets you in the ball park and alerts you to overcharge, but Zero accuracy.
John

Also, while the aux fan works, shouldn't it be on constantly when the A/C is engaged? I put the A/C on this morning on the way to work and the aux fan didn't come on at all, but I know it comes on when the car gets hot because I will often hear it before I start the car on a hot day when I stop at a store and then come back out to start the car.

No. The fan is actuated by a temperature switch. It won't operate until the refrigerant temp rises enough to close the switch. The fact that the fan works at all suggests that your refrigerant level is not excessively low. (A low refrigerant level prevents the temp from rising enough to actuate the fan.)

Okay, with all the heat lately, I have obtained permission from my wife to "do whatever it takes".

Now, with that out of the way, I have a couple of questions. I don't want to go back to R-12 and I do understand that 134a won't be as efficient, but I would think I could obtain reasonable cooling with a 134a system.

1) What parts do I need to upgrade to get an efficient 134a setup?

2) Where can I obtain these parts?

3) Does anyone know of a reputable A/C service place that:

a) Would be willing to work on this vintage benz

b) I could take the parts to this service center, they could evacuate the system, install the new parts, and recharge the system with proper oil and fridgerant

-OR-

Is there anyone in the area of Baltimore, MD that has such a machine that would be willing to help me out? I am willing to pay, buy lunch, etc. for the help.

I am fairly mechanically inclined, but again, the problem I have is evacuating the system so that I can install the new parts.

Again, I really appreciate everyone's input on this.

Any A/C shop should be able to work on your system. There is nothing exotic about the a/c system in your car, at least not the refrigeration portion. It uses a GM compressor and is very straight forward. Don't let anyone tell you otherwise; there is nothing special or unusual about that system.

If you want to do the work yourself, you could probably find a shop to evacuate the system for you after you put it back together. (That being said, there are plenty of shops that will do nothing to help a DIYer, even if it pays well.)

In any case, I highly recomend against a R-134 conversion. R-12 just isn't that expensive anymore. I just converted my '82 300D back to R-12 after sweltering for several summers with R-134. I am so happy with it that I can't see straight!!!

It was already converted to r134a before I purchased last year. It was purchased in Sept of 2005 so this is the first time I have really tested the A/C in hot temps.

Pardon my stupidity, but you are saying I can just unhook the lines and replace the condensor without having the system evacuated first? Won't the refridgerant currently in the system come spewing out all over the place?

The process of removing refrigerant from the system is usually described as "recovery." "Evacuation" is the process of removing air and moisture from the system prior to installing the refrigerant.

It would not be legal or environmentally correct to vent the existing R-134 into the atmosphere. So if your system curently contains refrigerant, you would need to visit a shop twice; initially for recovery, then for evacuation after the new components had been installed.

FWIW, my 300D is currently in the shop being converted back to R-12. I had it professionally converted (new compressor, dryer, expansion valve, etc) to 134a about 4 years ago after the compressor failed, for the usual reasons. The 134a was usually adequate for Denver, but it was never really cold. It would keep the car cool on the highway, but when the ambient temperature got to 90-95F and I hit stop and go traffic, it just didn't do very well. Overall, it was "good enough" but I was never thrilled by the performance.

Last weekend, the compressor failed (after about 150K miles) and I decided to switch it back to R-12. It needs a compressor, dryer, and flush anyway, so It's just the cost difference of the refrigerant between 12 and 134a. I haven't seen the total cost yet, but it should be under $1K. I'm looking forward to "real" AC again.

Yeah, now that it went down to about 90 today the A/C was adequate and cooled okay....so it must have been those couple of days we had 100 F that was just too much for it. I will probably do the same and just wait until something dies. I have other things I want to work on with the car so I will just have to put this off for a while. I was actually pretty comfortable driving home from work today and it was about 91 F here.

I don't know where you are located, but that sounds like my experience with 134a. Maybe a shop can "fine tune" the pressure a little and make it better, but don't expect much improvement. As others have said, you would need to upgrade the condenser to get significant improvements with 134a.

Yeah, well I will probably overhaul it before next summer. I want to stay with 134 so I will probably get an upgraded condensor and other upgraded parts to make it stronger. I don't know how old the compressor is either, so it could be getting weak.

__________________
2008 Jeep Grand Cherokee 3.0 CRD (OM642)

So with those temperatures, can I assume that you are very comfortable in the car even at idle?

Did you keep the oem evaporator? How about the aux. fan?

Could you tell me exactly which condenser you got and how you mounted it?

Thanks in advance for any input on this.


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1983 300D