Hi I have a 1985 300D the ac works and is charged, but I live in Phoenix, AZ and when it gets up past 105 degrees outside it just isnt cutting it. It is still using r12. Is there some kind of boost or adjustment, modification I can do? When the outside tempeture is 90 - 100 it does fine. But we have a good couple months at least in the plus triple digits here.

Kevinlee

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Mercedes 1985 300D 240k
Volvo 1985 240GL 260k

This is probably what you are looking for COLD AC

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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

No, his a/c is working and charged with the good stuff. It just needs to be tuned up a little.

Make sure that the condensor is clear and free of debris or bugs. If you can get to the evaporator, try to clean the evaporator as well. See that there are as few bent fins as possible on both evap and condensor. See that there are no bubbles in the sight glass. If there are bubbles in the sight glass while the engine has been running at 1500 RPM or so for at least five minutes, then the charge is most likely low.

You say it is charged, what are your pressures and at what ambient temp? What is the vent temp? You can get a dial thermometer to put in the vent at most auto supplies for about $5.

Post this info and we can advise further, but don't start ripping it apart or changing refrigerants.

Good luck,

I agree with everything posted so far. Also have two more options to toss into the fray -

1) On your car, the air conditioning uses 80% recirculated air and 20% fresh air. So you are mixed 20% toasty 105F air with your reciculated cool cabin air. You can modify the system to use 100% recirculated air. My 123 chassis car put out 5 degree cooler air when modified, with much less humidity. It made a nice difference on sticky 105 degree Dallas days. Here's a link to a writeup on the modification: http://db.mercedes.cx/mb/199904/15/0010.html

2) Don't underestimate the value of a good window tint job. A good metalized film tremendously slows the rate at which the cars interior heats up. As a result, the a/c can cool it down more quickly and keep it at a lower temperature.

- JimY

Now that sounds like something I could even do! Will I be able to identify the main air door and the fresh/recirc door hoses as to which is which?

By the way, I checked the condenser and it's clean with hardly any bent fins. No bubbles in the little window. I haven't got the gauge to check the actual temp yet but I know it's not as cold as I'd like.

I will attempt the mod above. That acutally makes alot of sense. 20 percent of scalding hot air would definately make it hotter inside the car.

Thanks
Kevinlee

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Mercedes 1985 300D 240k
Volvo 1985 240GL 260k

I have to replace the rear glass on my SD before I do this due to the old laminate pealing but it'll make a WORLD of difference... all my other vehicles are tinted and much cooler even without AC on. Llumar or 3M are brands I have used with good luck.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

Jim makes a very good suggestion for the window tinting. Even a 50% tint will give you almost 98% protection from UV, plus here's the math for the tint I used to calculate infrared heat:

I only tinted both rear passenger windows and the rear windshield. IF we assume that heat only comes through the windows, (it doesn't, but follow me on this for giggles) if we install a 50% tint on 50% of the total windows in the car, you effectively cut the heat load by 25% for the entire vehicle. Even if it is only 15%, that is a big chunk of heat reduction with NO increase in energy usage. I'm real happy with the results.

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84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)

Regarding the modification: Once you get the pushbuttons removed, you will be confronted with a horizontal row of five vacuum valves. Each has an electrical connector and each has a rubber vacuum hose attached. The far right one is to the main air door. The second from the right is to the fresh/recirc door. The other three control the defrost vents, the center dash vents, and floor vents - but I don't know which is which. The vacuum hoses are color coded - each has a stripe with one or two colors on it, all are different. With the official shop manual one can decode the colors - that's how I figured all this stuff out. But I sold the shop manual along with the car, toward the end of 1999. My friend is still driving it around Sarnia, Ontario. It's above 350K (miles) nowadays.

Before you start changing things, write down which colored hose is attached to which valve. Save the paper in the glovebox. That way you can put things back together again.

BTW, if you're going to do this, purchase a $5 dial thermometer. Stick it in the center dash vents to measure the temperature of the air coming out. We require before and after data on these types of projects, you know.

- JimY

How I wish there were pics taken with this info you provided, I'm going to do this to my SD and SDL here.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

Well I did the ac mod yesterday and I don't know if it made much of a difference or not. Or if it's actually working correctly. It feels pretty much the same.

I don't notice this taking place on my car. Also I forgot to test before and after temp. Although it was early in the morning (before the heat of the day) so I wouldn't have got a good temperture reading to compare.

I followed the instructions (which are pretty simple) and I'm sure I got it correct, I just don't know if it's doing anything.

I wonder if I should pull the glove box to see if the doors open or shut, or maybe just manually shut off the main air door. How would I do this?

Oh, I am going to get the windows tinted sometime this week as well, so that should help some.

Kevinlee

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Mercedes 1985 300D 240k
Volvo 1985 240GL 260k