First..love this car

Second..How difficult is it to recharge the ac for my car?

Third..What vents should open when the ac is turned on?

Local Benz dealer wants $300 for filling and checking the system.(85 per hour and $25 per lb of freon)

Local shop wants $90 for labor and $60 per lb of freon)

In anyones opinion, why the huge differences in prices?

thanks in advance,
Andrew
1998 Volvo V70
1983 300tdt 161k
1999 Honda Valkyrie Interstate
1974 Honda CB350f

There'e been a lot of discussion on this subject recently.

The cost of R-12 Freon has skyrocketed due to decreased supply and continued demand. $25 a Lb. is the cheapest price I have heard recently. Your system should take about three Lbs of Freon, so $180 + $90 = $270 for the independent, and about the same for the dealer. I'd go with the dealer in this case because there's more labor being done, and the freon cost is lower. The proper labor is really the key to getting it done right so it will keep working.

If the AC is working properly, the center vents will open. On my car, an '82 300SD, the system has to have sufficient pressure to open the pressure switch that's on top of the dryer.accumulator. No freon, no compressor, no vacuum to open the center vents. This keeps the compressor from burning up when there is no pressure to circulate the oil through it.

Done properly, and assuming that your system is empty, the system needs to be pumped out with a vacuum pump, flushed with the proper solvent to remove any crud, recharged with mineral oil and freon, and checked for leaks, and proper pressure.

Several DIY members here are proponents of recharging it yourself with R-134a, which is the environment friendlier replacement used on newer cars. I have heard many varying opinions on the effectiveness of this product, and the warnings of possible compressor failure within two years of doing the conversion due to the increased pressures of the newer refridgerant being circulated through a system that was not designed to use it. Even the die-hard supporters of R-134a conversion will admit that it doesn't chill as well as R-12.

Again, search the archives, do some reading on this subject, and come to your own conclusions. I hope that answered your questions.

__________________

Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."

Longston has given you some good advice & boiled it down to a reasonable synopsis of your choices. However, the above advice is correct except for a couple of things.

First, if the vacuum system is operating properly, the center vents *will* open in the ‘fresh air – cooling’ mode. The vacuum operated flap controlling the center vents sources its vacuum via a switchover valve that is controlled by the control unit. The center vents’ opening has absolutely nothing to do with whether or not the compressor is running.

Second, a correction in case you try to diagnose it yourself: the compressor will not engage unless the switch on the receiver/dryer is CLOSED (not opened) by system pressure. To believe otherwise you would rip your hair out of your head trying to figure it out.

Third, the dealer will charge you according to a ‘flat rate’ book to determine the labor charges. If the book says a procedure takes 1 hour, then you will be charged for 1 hour of labor, even if it only really takes the technician 15 minutes. Therefore the logic behind the statement that you will receive *more* labor at the dealer is flawed. Do not decide whether or not to take it to a dealer vs. an independent based upon flawed logic.

Fourth, if you are flushing the entire system, then the recommendation to use mineral oil is not necessarily a good one; it is a bit short sighted. Using an ester oil (not PAG & not mineral) will allow you compatibility with either R134a or R12. This way, if you decide to switch to 134a at a later date, you don’t have to go through the whole process again.

I agree with Longston about the R12. I would personally stick with the R12 if it were my car. This is of course a matter of opinion & great debate, so decide for yourself on that one. And People, PLEASE - Let’s not turn this thread into yet another ridiculously long-winded debate on R12 vs. R134. Those debates are second *only* to the utterly asinine lengths reached in the past on some threads about the minutiae of different coolants & who makes them. Oh, and then there is that pesky X-66 thread as well.

The best advice is to get a service CD if you plan on doing a lot of work on the car yourself.

PS: before the advent of the Quick-Lube type places, I know of one instance where a mechanic at a very busy dealership (an American Motors dealer – remember them?) was making a killing. He did *nothing* other than oil changes all day long. I can’t remember the exact numbers, but an oil change was charged at 1 hour of labor, and the mechanic got paid at the same rate. He could do several cars an hour, so he “worked” more than 100 hours per week & was paid commensurately. Not bad, huh?

RTH

RTH is killing me here...

However, First, ON MY CAR the center vents only open when the system is fully charged with refrigerant. Otherwise, they remain closed all of the time. The compressor does not need to run to open the vents, but the system must have sufficient pressure to make contact in the pressure switch or the rest of the system does not work. Now, I would appreciate any additional information on this, as I arrived at my conclusion by determining that I could open the vents by using my mity mite on the vacuum pot that controls them, then I found that bypassing the pressure switch caused the vents to open on their own, and the compressor would run, so I checked, and found that my system had no pressure.

Second, I see your point. Some people like electrical engineers will say a circuit or switch is closed because the terminals in the switch are making contact. I said open because this is a pressure switch that operates on spring pressure. when there is no pressure, the switch closes off the flow of electricity, and opens it up again when pressurized. So I was thinking in terms of this switch being something that prevents a flow of electricity. Like a valve, it would be "open" allowing electricity to "flow". I stand corrected. Sorry for the confusion.

Third, an assumption on my part perhaps. In light of this excellent point, I would ask both of them what they are charging you to do to your car, and compare labor-value. I was thinking in terms of the shop rate charges Andrew gave for the dealer @ $85 per hr. and the dealer was charging $225, (2.6 hrs). But that the independent was only charging $90, (1 or 1.25 hrs?). So, it would seem that the dealer would be doing a more thorough job to get the system running.

Fourth, I agree, and disagree. There is some wisdom to using ester oil if you are looking at converting at a later date, but if you don't need to flush the system there would be no need to switch. Besides, by the time you are ready to do the conversion in the future, you are likely to have to replace components and once the system is opened up like that you will have to purge it anyway. For more on these oils: http://www.delanet.com/~pparish/oil.htm

Interestingly, InterDynamics says that there is no need to remove the mineral oil when converting over to R-134a using their kits. Here's a quote from their website FAQ's: "What about the old oil left in the system? Don't you have to drain that? No. The mineral oil left behind will not mix with the R-134a refrigerant. That is why we add Ester Oil, because it will mix with R-134a and lubricate the system components. The mineral oil just finds a low place in the system, where it stays, until it is removed a some later date during future maintenance or repair. The mineral oil does no good, but it does no harm. It's just there."

http://www.id-usa.com/faq2.htm

And as for the oil change anecdote, guess what? That's still how it's done at boat shops, except that the mechanic can and does do several oil changes at once. They all get billed a flat rate, and the mechanic can knock out four or five an hour by using several electric siphon pumps. One for each boat, or moving the pump to the next boat while he does the filter change and refill. The system pumps into a five gallon bucket, and runs off of the boat's 12v battery...



[Edited by longston on 07-17-2001 at 10:01 AM]

__________________

Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."

Longston,

Your car is obviously not working as intended by the little gnomes in the Black Forest. (Yes, I know that’s a different company, don’t bother).

I know that you love to do your researching, but the response you got from Interdynamics (not to mention AC Delco with the X-66) is indicative of what you will get when you query any manufacturer. I mean, in the *real world* – do you expect that a manufacturer is going state anything OTHER than their product is the greatest thing invented since the wheel? Or that they may pull you aside and whisper in your ear that their product really isn’t *all* that good? That would be the fastest written pink-slip that any PR hack could ever receive. What if it was a lawyer or paralegal that was calling the company looking for an angle? Even if a company *knows* that their product had caused problems, they are not going to voluntarily open themselves up to liability. Corporate America isn’t that stupid, although certain individuals within them may be. I mean, you DO know that cigarettes do not cause lung disease & cancer, nor are they addictive, Right?

*In my opinion* Interdynamics, with their kit, is counting on the oil level being low enough in the compressor to begin with, so that the additional oil volume does not cause the compressor to lock up. In most cases, the resulting oil level will still be higher than the *proper* level. They are counting on the mineral oil to remain at the bottom of the compressor sump, while the newer oil floats above it (being that the two oils won’t mix chemically, but what about mechanically?). It may work, but for how long? My engineering degree has a large watermark of Mouse-Ears on the parchment, and yet I still wouldn’t do it that way. Speaking of water, I could pour a quart of water in my engine – the oil will float above it; and as long as the oil pickup tube isn’t lower than the boundary between the two I’ll be OK, right?

But let’s get back to Andrew Fekete’s original questions, shall we?

First, you love the car. Completely understandable.

Second, is it easy to recharge? Comparatively, yes – there’s nothing magic or significantly different from any other car as far as the refrigerant circuit is concerned.

Third, which vents should be open? It depends on which button you have pushed. In one setting, all of the vents on the dash should be open, plus you may get a leak portion out of the defroster & legroom vents. With the other button, the center vents will close and the defrost & legroom vents will open.

Four, Five & Six: Why the difference? Because they can charge whatever the market will bear. Remember that people need to make a profit & a living, and I should tell you that the $25 per pound is below the price at which R12 is available here in California, even when purchasing it in 30lb tanks. (Since I can’t buy it, I haven’t exactly tried real hard to find a lower price, so it may be out there) Is the dealer giving it to you at cost?

A word of warning: At the $85 per hour, the dealer is going to get VERY expensive in a hurry if they find that a component needs to be replaced. After all, the freon did leak out of somewhere, unless the system was opened for some reason.

Best of Luck!
RTH

Here is my two cents on R12 R134 debate,


I just had my car 84 300d retro fitted after alot of internal debate. THe basis of my decision was that I plan on keeping this car for a while so R134 would be a cheaper and potentionally better solution as R12 availability. The retro fit went well but my car blows cooler air and I want cold air. It works well enough but I am a bit disappionted. In final analysis, If you are willing to make a mistake and through away some good money in the desire to have cold air go with the R12 and proper repair of any leaks. If You want to be more cautious, have cool air, and make the more logical decision get the R134.

I now wish that I Put in the R12.

Be aware tha the cost of replace the R12 is alot if your leak in not repaired. The cost of R134 is about $18 with the do it yourself kit.

I hope that this helps.

bob

Thanks for all the info folks. I believe I will take it to the dealer and let them do their thing. If teh system hasa a problem I would rather have it fixed. I plan on keeping the car for quite a while. I'm fairly good with a wrench and I'll know if they are trying to get the best of me.

Last time I had in the shop my tranny was replaced with a new one. The dealer did the replacement for $350 plus the cost of the trans ($1700).

I will be working on changing the motor mounts, engine shocks, and front shocks this weekend.

Just a quick question: someone made mention of a service CD-ROM? Where could I get one of these? Is if more complete than the Chilton's manual? I want to try and recharge/convert my air conditioning system but the chilton's manual doesn't say anything about it. Thanks a lot

Alex

__________________
1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

From PartsShop / FastLane. They are basically scans of the Mercedes Factory Repair Manuals on disk. There is also a Haynes manual that I think applies to your car. I don't know if you can get one from here, but call Phil at 1-888-33-4642 and ask him.

As for the AC recharge/retrofit, you can get a lot of information by doing a search through the archives right here on MercedesShop, using the search button at the top of every page. You can also go to the Interdynamics webpage at http://www.id-usa.com, because they are a major manufacturer of retrofit R-134a kits. And/or do a search on the subject using any reliable internet search engine.

__________________

Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."

Andrew,
Its very easy to change your car over to R-134a.
I just did myself for a cost of $33.
1.Make sure your system is completly dry of the R-12.

2. Buy the conversion kit (Walmart is where i bought mine).
You do all the charging on the top (low side fitting). Just read all the directions on the kit. Be sure not to add to much, our cars (1983 300TD) take 2.2lbs of R-12. Your car will have a little i think red sticker on the front passenger side hood aera. The capacities are different for R-134a. I put 2.5 cans in myself.
3. The center vents will operate SOMETIMES!!! I just read the owners manual on this. No matter if its on economy or A/C the center vents will work depending on temp/humidity. So this means they will not always blow through the centers. Of course if air NEVER blows through the centers, your valve is not opening those vents. Play around with those buttons switching from off-econ-A/C a few times and sometimes this can trigger them to work.
I hope this simplifed your questions. I have the same car and just converted myself a month ago so if you have any additional questions once youve decided to buy the kit let me know!
Brett

Jeepboy: One thing that you did not mention was if the temperature drop was the same as with the R12. Not likely, however it may be adequate for you, or for other people that live in climates that are not very demanding on AC systems.

I guess that I was not clear about the center vents in the prior posting – sorry about that. I stated that the center vents are open in the ‘fresh air – cooling’ mode. It is the same as during ‘AC - cooling mode’. The key difference is in the cooling vs. heating modes. They will be closed in ANY mode other than cooling, i.e., heat & defrost modes.

RTH