Seltsames Klima-Problem | Posts 16+

Hm, is a 3A5 actually a Passat 35i? I wonder.

T3Surfer wrote:

Rüdi, In the Passat, the air conditioning system uses a THROTTLE system, where the dryer is located on the low-pressure (LP) side! In the Golf, for example, it uses an EXPANSION VALVE system, where the dryer is located on the high-pressure (HP) side! These are the differences! In the older Passat 35I with the transverse engine, it's an expansion valve system! In the 3B Passat with the inline engine, it's a throttle system!

Who told you that nonsense?

A dryer always works best on the sunny (HD) side, as it achieves its optimal performance when it's warm, while it's too cold on the shady (ND) side.

Whether it's a throttle valve or an electronic control valve, the effect is the same: a pressure drop from the high-pressure to the low-pressure side to vaporize the refrigerant.

I happen to have a Passat 35i from 1991, a 35i (3A) from 1996, and a 3B from 2000, and all of them have the dryer located on the high-pressure side, behind the condenser.

What you might have seen and mistaken for the dryer is the muffler in the engine compartment, on the right side, above the air filter.

Hm, ist ein 3A5 überhaupt ein Passat 35i ? Ponder.


Yes, 3A5 refers to the station wagon (Variant), while 3A2 refers to the sedan (Limosine), likely manufactured between 1994 and 1996 (representing a facelift of the so-called 312 sedan and 315 station wagon).
The successor is a 3B2 or 3B5 (model years 1996-2000) - 3B.
The successor is a 3b3 or 3b6 (model years 00-06) - 3BG.
and the current model is the 3C - 3C2 sedan from 2005 and the station wagon from 2006, both designated as 3C5.

Although I think I learned quite a bit during my studies, the statement made by 'T3Surfer' seems very abstract to me – at least, it's new to me.
Certainly, the structure of Rüdi's statement aligns with the framework presented (which is clearly visible in the diagrams in the guide).

Today, I examined the following phenomena and observed the following:
# Air conditioner turned on -> the thick pipe (ND) is cool, the thin pipe (HD) is at ambient temperature.
# Shortly thereafter (10-20 seconds) -> the large diameter pipe (ND) reaches ambient temperature, while the small diameter pipe (HD) becomes extremely cold.

The following was observed on the so-called refrigerant dryer vessel: The inlet side was warm, while the outlet side was cold (I hope I haven't mixed up the inlet and outlet). The vessel itself, although not as cold as the cold section of the pipe, was still noticeably cool (not warm to the touch). The upper part of the vessel was slightly warmer than the bottom, but still relatively cool, as felt by touch. So, warm air goes in, and cold air comes out – which is quite strange. Either there's a problem with the dryer itself, or possibly with the expansion valve. If the expansion valve were open, and the dryer provided the only resistance in the system, then expansion and cooling should occur from that point onwards.

Regarding the compressor, I'm also not sure if it's actually disengaging. It's very difficult to tell from the pulley, as it's located underneath the alternator and in an awkward position.
Definitely, repeatedly pressing the accelerator pedal causes me to hear the magnetic clutch click at idle speed – I assume it's trying to engage.

Regarding heat generation, the alternator (when the engine is off) is significantly warmer than the compressor (which is only mildly warm).

Sorry, a lot of text..

Hi.

Okay, I also have a 1996 Passat 3A, and I can easily identify the pulley with a flashlight.

When the accelerator is pressed, the compressor is switched off and then switched back on.

However, if the dryer is getting cold, that's a sign that this is the cause of the blockage. A new part costs around 35 euros, so replace it. Also, get new O-rings beforehand and lubricate them well with refrigerant oil to ensure a good seal.

We recently had a Neoplan bus with similar issues at the company. According to the owner, the dryer had only been replaced 6 months prior, so we searched everywhere, but the problem turned out to be with the "dense" dryer.

Best regards, Rüdi.

As far as I know, the compressor only switches off when the accelerator is fully depressed, but remains active in the lower range (reason: excess power for overtaking maneuvers, etc.).

Unfortunately, it's not going to work to do it yourself - you have to drain the R134a (without pressure), then replace it, flush it with nitrogen, and then refill it - but you probably already know that.

Rüdi, I'm not telling you nonsense! I myself have taken a climate control course and I repair and maintain automotive air conditioning systems! Here, see the throttling system and how it works: https://community.dieselschrauber.org/en/viewtopic.php?t=3475


There are different systems!

Sure, no problem. Just let it be evacuated, replace the dryer, and then evacuate and fill it again.

Replacing the shock absorbers can quickly cost around 200 euros, and you also need to remove the front strut if you want to do the job properly.

I'd rather earn my own money.

Best regards, Rüdi.

T3Surfer wrote:

Rüdi, I'm not telling you nonsense! I myself have taken a climate control course and I repair and maintain automotive air conditioning systems! Here, see the throttling system and how it works: https://community.dieselschrauber.org/en/viewtopic.php?t=3475 There are different systems!

It may be true that one can't know everything, but in this particular case with the Passat, the dryer is located in the fluid line, as is the case with most systems.

"I didn't take a climate course, but I learned the trade of refrigeration technician and I work in that field. I repair transport refrigeration systems (Carrier, Frigo-Block, Kerstner...), bus air conditioning systems (Konvekta, Webasto, Thermal...), and car air conditioning systems of all brands that come in."

Mullemaus: Thanks for the info! I'm a little wiser about the type designation now!
Rüdi: Wow, you're working on some big installations! I only do installations for passenger cars, all brands. It's impossible to keep track of all the different systems that various manufacturers use.

T3Surfer wrote:

One cannot always know which systems different manufacturers use.

I can't do that either, but I own the vehicles mentioned on the first page, and by chance, I replaced the 3A condenser and dryer in a 1995 Passat at my company on Friday.