Problem with airconditioning on 155 2.0 16v super

Hi there!

I need a little help with my car. the aircon is not working the way it should.

The problem is: Starting the engine with the aircon turned on, the pipe leading
away from the compressor gets cold quite fast but just for a few seconds. Then
there is a clicking sound (relais i guess) and the pipe gets warm. While
driving with revs about 2500 and speed around 50 km/h the air reaching the
passenger compartment is as cold as it should be with aircon turned on. When
stopping at a light for more then a minute or so: there is the "Click" and the
air comming in gets warmer and ..uh.. humidity rises fast as well.. and the
smell...bah..
Driving again and all gets back to normal function.

What i checked and did until now:

- The passenger compartment filter is new, been in for two months.
- The r134 level is checked and 750 grams of it are where they are supposed to
be.
- System has no leaks
- Yesterday i found a resistor which had been blown (notice: fuses are all ok)
the resistor is next to the cooling fan and a mec told me that the resistor
is needed for switching the fan from level one to level to. Weird thing about
how that thing died: one of the two cables was melted(!) as well as a part of
the plastic housing. The insulation of the cable has nice little bubbles at a
length of ca. 5 cm. That heat didn´t come from anywhere else but the
resistor.

- I was given the hint to change the dryer/filter(?) of the aircon (aluminium
housing, two high pressure connections) to make sure the system runs all
right.

It might help. Damn expensive part though.(about 100 euros)

- one of the little valves at the tubes near the compressor was leaky, throwing
out a few small bubbles
(normal tire valve) and was changed. Maybe that was an inication that
something was choked and the pressure inside the system is too high.

I really hope someone can help me or give me a few hints which other parts i
could check and how.

Thanks in advance,

Ralf

Ralf Hocke skrev i meddelandet
>...
[snip]
>- Yesterday i found a resistor which had been blown (notice: fuses are
all ok)
> the resistor is next to the cooling fan and a mec told me that the
resistor
> is needed for switching the fan from level one to level to. Weird
thing about
> how that thing died: one of the two cables was melted(!) as well as a
part of
> the plastic housing. The insulation of the cable has nice little
bubbles at a
> length of ca. 5 cm. That heat didn´t come from anywhere else but the
> resistor.
>


The cooling fan has two speeds. The resistor is used for the low speed
mode.
If it is broken, the engine temp will rise a bit higher before the fan
cuts in, close
to 100 C and then the fan will run at full speed. This could possibly
affect the
operation of the AC. Either way, it's a rather easy fix and it's
probably good for
the engine to have the low speed so I think you should start by fixing
this resistor.

/Henrik

(Henrik Johnsson) wrote in <2o4s3nF6vv7rU1@uni-
berlin.de>:


>
>The cooling fan has two speeds. The resistor is used for the low speed
>mode.
>If it is broken, the engine temp will rise a bit higher before the fan
>cuts in, close
>to 100 C and then the fan will run at full speed. This could possibly
>affect the
>operation of the AC. Either way, it's a rather easy fix and it's
>probably good for
>the engine to have the low speed so I think you should start by fixing
>this resistor.
>
>/Henrik
>


Oh yeah, it did help.
Put a new resistor to work two days ago and the problem with the a/c is
gone. That was almost too easy. After installing it, I tested the a/c with
the engine idling. After a few secs the fan started up and the air comming
out from the ducts inside the car was as cold as it should be and while
driving the water temp does not go beyond 90 degrees celsius anymore.

So it took just a few minutes of installation and a few euros (17,95 for a
0,18 Ohm resistor, what bargain...) This time to fix the trouble.

Do i have to say that the garage had some different/more expensive ideas?
:-)


Ralf