Manual air conditioning system not working.

Hello there

I own a Bora Variant, manufactured in 2000, with a 1.9 TDI PD AJM engine (85 KW).

Just in time for the warm season, my manual air conditioning unit is no longer producing a cool breeze. After checking all the fuses, which showed nothing, I went to ATU and hoped that the air conditioning unit was malfunctioning due to a low refrigerant level. Unfortunately: Even after the one-hour evacuation procedure (which should only justify the price), there was still only warm air. When I tried to read the error codes at ATU, it was not possible. My attempt to get any error codes out of the air conditioning unit also failed. Is there a diagnostic unit that can diagnose problems in manual air conditioning systems?
Well, so I started to conduct more detailed investigations in the engine compartment with the following results:

- The magnetic coupling is not being addressed, but it functions when power is applied.
- The fans do not turn on when the air conditioning is switched on.
- A power-on signal is coming from the interior.

Under the battery box, there is a relay or similar component attached with the following designation: 1J0 919 506 E, or SHO 898 838 000

Since both fans, the radiator thermostat, the air conditioning magnetic clutch, another temperature sensor in the engine cooling circuit, a sensor for outside temperature or pressure, and the sensor mounted on the air conditioning circuit are connected to this relay, I suspect that the air conditioning control runs through this relay. When I press the A/C button inside the car, a voltage is also present on a cable that comes from inside and goes to the relay. So, I assume that either this relay or one of the various sensors connected to it is defective, or that the problem lies in the cooling circuit, because a sensor is sending a shutdown signal to the relay.

Can anyone confirm my previous research findings and/or offer advice regarding my problem?

I would be very grateful.

Greetings,

Rolf

Even after the one-hour evacuation procedure (which should also justify the price), only warm air.


The extended evacuation is not intended to 'justify the cost,' but is mandated by vehicle manufacturers (and climate control manufacturers) because it is simply necessary.

You have an email.

If any further questions arise, please simply post them.

Greetings
Private

BigPub116 wrote:

Hello I own a Bora Variant, manufactured in 2000, with a 1.9 TDI PD AJM engine (85 KW). Just in time for the warm season, my manual air conditioning unit is no longer producing a cool breeze. After checking all the fuses, which showed nothing, I went to ATU and hoped that the air conditioning unit was malfunctioning due to a low refrigerant level. Unfortunately: Even after the one-hour evacuation procedure (which should only justify the price), there was still only warm air. When I tried to read the error codes at ATU, it was not possible. My attempt to get any error codes out of the air conditioning unit also failed. Is there a diagnostic unit that can diagnose problems in manual air conditioning systems? Well, so I started to conduct more detailed investigations in the engine compartment with the following results: - The magnetic coupling is not being addressed, but it functions when power is applied. - The fans do not turn on when the air conditioning is switched on. - A power-on signal is coming from the interior. Under the battery box, there is a relay or similar component attached with the following designation: 1J0 919 506 E, or SHO 898 838 000 Since both fans, the radiator thermostat, the air conditioning magnetic clutch, another temperature sensor in the engine cooling circuit, a sensor for outside temperature or pressure, and the sensor mounted on the air conditioning circuit are connected to this relay, I suspect that the air conditioning control runs through this relay. When I press the A/C button inside the car, a voltage is also present on a cable that comes from inside and goes to the relay. So, I assume that either this relay or one of the various sensors connected to it is defective, or that the problem lies in the cooling circuit, because a sensor is sending a shutdown signal to the relay. Can anyone confirm my previous research findings and/or offer advice regarding my problem? I would be very grateful. Greetings, Rolf

Hi Rolf,

I'm not very familiar with air conditioners, but it's likely that you have a pressure switch in the refrigerant circuit that opens a contact and shuts down the compressor when the pressure is too low (== no refrigerant).
On my A3, for example, this switch is located on the splash shield in front of the expansion valve.

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Hello, Rainer

Also, the thermostat on the evaporator could also be faulty. It switches off the compressor and the fan if the temperature is too low, in order to prevent, among other things, the evaporator from freezing. If this is no longer closing, the compressor will not start.

Greetings, Holger