AC upgrades/improvements - Page 4 - PeachParts Mercedes-Benz Forum

81Wagon · #46 05-11-2004, 10:26 AM

So far so good. I've gotten my old condenser out, and the new one got here yesterday. Here they are side by side... The new one is slightly taller (half inch or so) and the width is essentially the same. It's slightly thinner. Today or tomorrow I'll get it mounted on the car and figure out the exact dimensions of the lines I need to have made, so I can take it to a local AC or hydraulics shop and have them whip it up for me..

smartin · #47 05-11-2004, 09:39 PM

What size is that condensor (parallel flow)? I am looking into doing the same thing. Thanks Steve

leathermang · #48 05-11-2004, 09:50 PM

OOPS....
on page one he said " I plan to use this condenser from ACSource.com "

which was this site :
http://www.acsource.com/index.asp?PageAction=VIEWPROD&ProdID=133

lucforce · #49 05-18-2004, 01:19 AM

A few notes for those retrofitting and otherwise altering a/c systems.

There is a direct relationship between gauge readings, elevation, and ambient temp.-refer to the standard charts.

Depending on the system, pressures are to be checked at 1500-2500 rpm

High side pressure is typically higher after convertion to 134-a.

ALWAYS install a pressure switch on the high-side line that will shut off the comp. at extreme pressure.

jcyuhn knows more about the functioning of these systems than what you give him credit for. Low refer. charge can definately cause evap and line freezing(note that if you have internal line freezing, you have other issues-though I believe this to be nearly impossible)

parallel condensors are slightly more efficient and were primarily developed to overcome the high side pressure increase (compared to r-12) of the 134-a. Some makes simply must have one in the conversion process, M-B is not one.

When replacing hoses, use barrier-type hoses.

Change the oil in your compressor when servicing and use the proper oil for your refri.

Upgrade to the blue and green "o" rings.

If your drier/accumulator is more than three years old-replace it with one containing the best dessicant possible.
If the system is open more than a couple of hours and the drier is not new, replace it. If you had any restrictions in your system or compressor damage-replace the drier.

Spend the money on a known brand of compressor- especially the r-4. The r-4 is not a well made unit to begin with, skip the cheappy rebuilds.

engatwork · #50 05-18-2004, 07:28 PM

I finally waded through this thread and will be installing a p flow condenser in a 300SD and plan on keeping the r12 refrigerant. I got the condenser from Plantman and it looks like it should fit like a glove with just some modifications to the hose ends which I will get the local hose house (Tubes N Hoses) to help with. I'll keep ya'll posted.

smartin · #51 03-25-2005, 01:43 AM

The adjustment to the evap temp sensor - is it a screw that is under a removable plastic cap? How much do you you turn? I get 41 at speed (60 mph) Outside temp in the 80s.

Thanks

Steve

leathermang · #52 03-25-2005, 07:01 AM

Steve, I am going to play the odds here ( not really much gamble due to overwhelming numbers ) and tell you right up front that you are looking at the wrong place in the car to change what your problem/s is/are.
You need to start back at the basics... clean and straighten your fins on your condensor AND your radiator, check your aux fan and engine fan for proper working, check your system for proper charge of refrigerant , etc...before you EVEN think about the expansion valve adjustment. The very last thing on a list of things which would adversly affect your ' cool ' .
If you mess with it and mess up the setting then you are going to crack your reed valves on your compressor at the very least... and probably break something inside the compressor due to hydrolock.

smartin · #53 03-25-2005, 11:56 AM

Thanks for the response.

Everything in the system is new (evap. parallel flow condensor, all hoses, dryer, evap temp sensor, expansion valve, all vacuum pods, pressure and temp switches on drier, temp switch on engine, aux fan)- I am running with R-12. System does cycle - comp/fan go on and off. I will check pressure readings (with help) - are these affected by the fact that I have a parallel flow condensor? Can someone suply these readings - at what rpm do I test?

Thanks again

Steve

leathermang · #54 03-25-2005, 12:08 PM

Steve, you can not find enough information on this site to do what you are wanting to do SAFELY....
You need someone who has done this before to show you the first time...
And be sure both of you are wearing safety goggles.....
The figures you ask about are on a chart which has other things on it... it is not just one setting.... you check your ambient air temperature, put your guages on, etc....

If all those things are new on your car I can see why you are thinking that screw needs to be turned... but trust me on this.... something ELSE is keeping you from making the cool air you want....

Why don't you tell us exactly how the replacments fit, who put them on, what kind of vacuum pump you used to evacuate it , did you flush the system ? , What did you use to flush ?, and what pressures were on the system when you started driving /testing it ?

crazy banana · #55 06-19-2005, 01:16 PM

any update on this thread??? how are everyone's upgrade turned out??

dmorrison · #56 06-19-2005, 02:19 PM

I will add to this post to keep the info going.

In my 1982 300TD, I replaced everything on the AC system. All new parts and a parallel flow condenser.
The post about the conversion.

http://www.peachparts.com/shopforum/showthread.php?t=99598&highlight=parallel+flow+condensor+dave+300td

The compressor just seized after 1.5 years of running, not happy with that. Another post shows this and I have not opened the system yet (6/19/05)to determine a cause.
We drove my daughters 240D to Church today, its a R12 OEM system. IT COOLS MUCH BETTER THAN MY R134 PF CONDENSER CONVERSION. And I think it may be a speck low on freon. She has a very small leak in the evaporator. It was fully charged last summer, sets off the sniffer when sticking it in the evaporator box, but still cools better than my wagon after 1 year with a "leak"'.

SOOOOOOO

I will be fixing the 300TD system, whatever it takes and returning it to R12, with the parallel flow condenser ( I will post vent temps and all, when complete). I realized while driving the car today that the 240D system was just better.

Did the conversion work, yes. Would I recommend it to anyone, yes. With the R134 setup that I have, the car would cool great in normal non stop and go traffic. In stop and go traffic you could tell the vent temps were rising. This caused by the inability of R134 to transfer heat and the capacity required in a condenser is just so much greater when using a R134.

So if you are going to do the conversion. Consider the following.

1. The largest PF condenser you can install. Consider cutting sheet metal and new hoses.
2. I, up to this decision point, was considering going with a large aux fan or 2 installed next to each other. Wire the fan to turn on when the AC system is on.
3. Consider, this was discussed in other posts, using a larger dryer or possibly two in series. This will hold a reserve of condensed freon for the expansion valve while at a stop light or stop and go traffic.
4. Use synthetic oil so that you can move between R134 and R12 without flushing. The synthetic oil is good for both freons.
5. If you are above the Mason-Dixon line I would not hesitate in any way to do the conversion, If in the Texas or SW desert areas consider the benefits of R12. Get the 609 license and keep it original.

BUT, this it Texas, and since I have my 609 license and R12 is getting cheaper while R134 is going up in price. I have decided to re-convert back to R12. Again driving my daughters 240D made the decision for me.

Dave

leathermang · #57 06-19-2005, 03:13 PM

" Consider, this was discussed in other posts, using a larger dryer or possibly two in series. This will hold a reserve of condensed freon for the expansion valve while at a stop light or stop and go traffic."---dmorrison

I would suggest putting those in parallel....
with the proper additional fittings you could even change them out one at a time without evacuating the refrigerant from the system...
In series I would worry about additional friction and with the oil positioning.... where in parallel it should just provide the improvement described above.

wols0003 · #58 06-19-2005, 10:34 PM

Smartin wrote, "I get 41 at speed (60 mph) Outside temp in the 80s.

The factory manual states that the compressor cycle off-point should be between 39 and 41 degrees vent temps. So, your system seems to have been working just fine. I get 39 vent temps before cycle-off, I was also thinking about turning down the evap-temp-cuttoff. However, After I thought about it I realized that it really is no advantage to have the cycle-off point lower than 39-41 degrees, because when the temps are really hot, your system will not get even close to the cuttoff point (except on low fan speed). In other words, where I live during the summer-daytime, my compressor never cycles off; so there would be absolutely no advantage to having a lower cycle-off point. Further, when its 85 degrees, why would you need 36 degree vent temps? Lower vent temps also creates more condensation in the air ducts and causes the musty smell.

coachgeo · #59 06-20-2005, 12:09 AM

Seems to me the paralell flow condisor is not really needed. Just a complete clean functioning system with something better than R134 for a refrigerant.

Now... for getting all the vacuum activated flaps and ECU stuff working right.... that is a different story. Is this the area where "conversion" is really needed?

erubin · #60 06-20-2005, 01:04 AM

A little over a year ago the A/C compressor in my 1982 300D turbo smoked (yes it looked like the car was burning from under the hood). i wonder now if it was from the belt slipping over a seized/partialy seized compressor? After flushing the system i found a few chunks of metal. It didn't look like black death cause it was only gun metal color inside. The system was converted to R134 by the PO's mechanic. i decided to keep the system with R134 cause primo I don't need a tremendous amount of cooling capacity in our mild SoCA climate, and for various reasons R134 is easier for me. BTW, the price of R134 has really jumped up, as much as $12 for a 12oz can! For whatever/whoever it's worth here is what i have in my notes on the repair I did.

New A/C compressor (4-seasons, R4), R/D, expansion valve, R/D temp sensor. All new green o-rings, schraeder valves and nylog, 6oz BVA Auto 100 synthetic Pololesters (4oz in compressor, 2oz in R/D). initial flush with 1 1/2gallons 100% mineral spirits (just $5/gal. at Sears) followed with 2 quarts Dura 141. Wrapped exp valve with sticky insulation. Used the included yellow and green sealing washers on compressor, did not use the included insert. Evacuated for 3 hours at 90F (28.75” Hg). Three 12oz cans of straight (no tracer) R134. Removed some next day, ~4oz? to optimize system. Ambient 90F 40% RH, Condensor fan bridged on, blower set to max, 1500-2000RPM, Low pressure 25~30psi, high pressure 290-300psi, center duct temp 46F. All new drive belts.

Haven't touched the system since the above was written 14 months ago and it's blowing fine. Would hate to see it fail again since the above represents over $300 in parts.