[R129 SL] Another air conditioning question

Jan Kuylaars J.kuylaars at kpnplanet.nl
Sun Jul 15 16:24:03 EDT 2007


Peter;
Yeah, it should be better to buy a foam fire Extinguisher. When you need
it, it is worth the extra amount of money for saving the rest of the
car.
But I also have at home and in my car a powder one.
I shall replace the one in the car and give the powder to someone else
for free.

Last month I let replaced the clutch with all parts from my Mazda 929.
Now my 500 SL is standing still in my garage I was happy to have this
car as spare.
Using it this weekend my clutch pedal stays on the floor an I could not
shift anymore. Let it ride in second gear I was driving to my mechanic
hoping I did not have to stop for a traffic light. Then I take my foot
under the pedal and pull it back upwards. After that I could use the
clutch again and after shifting some times I drove back at home. When I
was home I checked the oil level from the clutch pedal. It was between
full and minus, it was not clear anymore but grey.
I took out the amount of grey oil and cleaned the reservoir with a
cloth. Then I filled it with new brake oil. Testing it results in good
working.
So I hope this will save the problem. Otherwise I must replace the cups
in the pedal cylinder.

The sun was shining and we have a temperature of more than 30 degrees
Celsius. So I thought I take my Yamaha 1330 Venture bike and use it this
weekend.
The first thing I thought was: it will not start. And yes, I was right.
Starting it with help from my Mazda battery let it rues normal.
So I drove some miles , but takes starting cable with me for sure. And
that was necessary. After shut down the bike it would not start again.
Help from a nice lady solve the problem for a while and I drove home.
Having the battery one night on full charge it started this morning
without problems.
But after starting several times I measure the voltage on the battery
and while the start motor hacked, the voltage dropped under 6 volts.
So tomorrow I am going to buy a new battery. Then my back tire what has
been replaced last winter for new, had only 1.5 bar left.
Visiting 3 gestations before I find a air pump what I could use on my
back tire .

After this I have checked all fluids and all pressure's on all my
vehicles and asking myself what will be the next failure.

But I droved some miles today with nice sun .

Greetings from Jan.


-----Oorspronkelijk bericht-----
Van: r129list-bounces at mbcoupes.com
[mailto:r129list-bounces at mbcoupes.com] Namens Peter Shelton
Verzonden: zaterdag 14 juli 2007 1:17
Aan: SL Mailing List
Onderwerp: Re: [R129 SL] Another air conditioning question


Hi Jan,

Not good about your gearbox. I have spares for 201's and 123's but not
for a 129. I bought a brand new 129 left headlight off "trademe" (NZ
equivalent of EBay) last week. Bought as an 'in case' spare. genuine
part - $125 euros. Amazing what people have in their sheds!

Jan, after 'frying' your gearbox, maybe you could call yourself the
"Frying Dutchman" rather than the "Flying Dutchman"! It nearly sounds
the same?.

One of our newer members in our NZ Mercedes Benz Club recently bought a
1974 350SL. The fuel line leaked and the engine caught fire! Did a
bit of damage but it was extinguished with a Fire Extinguisher. It was
a dry powder (mica) type - what a mess it left and it is corrosive!
Also no insurance for this in NZ and he is an insurance agent/
investigator. I have nick named his car "The Barbeque" for obvious
reasons. I suggest we all check our fuel lines frequently as perishing
fuel lines can be fatal.

Jan, your description of the aircon is very good. It is important to
measure the on/off coil temperatures as this gives an immediate
indication of where the problem may lie. Bubbling in the accumulator
sight glass is also an indicator.

Great sunny day in Eco City (Manawatu NZ). The day started off at
minimum 2 and it is about 15 degrees now. It is hot from the sun, as
the ozone layer over our country is depleting fast, and the UV filtering
effect of Ozone is nearly non existent. Well, time for a ride in the
500SL, have to make the most of the sunny days.

Regards, Peter S.

----- Original Message -----
From: Jan <mailto:J.kuylaars at kpnplanet.nl> Kuylaars
To: 'SL Mailing List' <mailto:r129list at mbcoupes.com>
Sent: Friday, July 13, 2007 10:30 AM
Subject: Re: [R129 SL] Another air conditioning question

George.

I am not a expert in AC, but basic working is that the compressor
compresses the gas to fluid and the fluid is giving of the heat that is
produced by compressing.
The front radiator is for cooling the heated fluid by passing air while
driving, or by air stream with the electric fans, during standing still.
The heated gas is pumped to the receiver drier to take out the moister.
After the drier there is a pressure control switch for shut down the AC
if the pressure is to low and a other for running the electric fans if
the pressure is to high.


If you system is not completely filled, you can see air bubbles in the
glass from the drier when the compressor is running.
When you see no bubbles there is to less or no refrigerant.You can check
on the compressor. There should be a different in temperature in the
inlet and outlet
After the compressor stops , and there is a clear vision in the glass,
there is to much refrigerant in the system.
If the amount of refrigerant is perfect, the refrigerant should foam and
then stay clear after the compressor stops.


>From the drier the fluid runs to the evaporator inside the car , where

the fluid can expand to gas again, and for this expand the gas needs
heat.
The evaporator takes the heat from the room and the room becomes cool.


>From the evaporator the gas is flowing back to the compressors low

pressure side, where the gas is compressed again to fluid and the
process starts again.

So as long as your car is driving and the radiator will be cooled there
is no problem.
When your car is standing still and the engine temperature is climbing
the problems starts;

There are in mine opinion two possibilities, I am not for sure , but I
am are trying to think with you :
First there could be a failure in the basic operation, and the second
one is electronic problem from the regulation of he AC.

Lets start by the first: if your car is standing still and your electric
fans are not working, the fluid is not been cooled and the heated fluid
results in higher pressure .
Also there is a higher temperature in your evaporator. There is
expanding from the gas but it don't needs a lot of heat for this because
the temperature already is high. The result could be that the emission
of heat out of your car to the evaporator is gone. So no cooling.
This could be resulting in a spiral. After the pressure comes too high
the system shut down or the refrigerant will come out the high pressure
security valve.
Result to low refrigerant and not proper working of the AC.

Possible failure could be the fans, the fan control, the pressure switch
or the expansion valve which are not good operating with higher pressure
or heat.

Then there is a possibility for electronic failure , like the Italian
college told; The measure of inside temperature and outside temperature
in combination with the temperature from the engine. He told us to fix
this problem with a resistor placed in series with the engine
temperature sensor. Read the earlier messages.

Also there can be a failure in the circuit itself.
When you wish I can send you the electronic circuit diagrams and the
diagnose procedure.

Greetings from the standing still Dutchmen with damaged gearbox.

I discovered on the bill from my garage that beside replacement from the
starter and the steering house, they replaced the rubber pipe from the
gearbox oil cooler because it should leak a bit. After that I only drove
40 miles before my gearbox looses oil with pump noise and burned oil on
the exhaust as result.
I must check if the rubber pipe is come loose, and maybe they are the
reason of no just oil level or other damage.
But then I have a problem if they are willing to confess and pay for the
damage.

Jan.











-----Oorspronkelijk bericht-----
Van: r129list-bounces at mbcoupes.com
[mailto:r129list-bounces at mbcoupes.com] Namens George Jenner
Verzonden: donderdag 12 juli 2007 15:59
Aan: SL Mailing List
Onderwerp: [R129 SL] Another air conditioning question


I have been experiencing a perplexing problem with my 1996 SL500 air
conditioning system. I have the means to check the pressure on the
system and have noticed that when I first start the car the air
conditioned runs normally cold. As I drive and the car heats up the
system runs normally, but if I turn off the engine (to gas up) and the
out door temp. is hot (in the high 90s) when I restart the car the air
conditioner is no longer running cold. This has led me to check the
system pressure at various engine temperature stages and the pressure is
in the normal 40 - 50 range when the system is cooling normally but
jumps to 100 + when the engine is hot and the system no longer is
cooling. I do not think I am loosing coolant but need help to locate
the problem.

Has anyone any idea of what may be causing this problem?

Thanks, George



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