Auxiliary Heater Z35 Not Connected

Hello,

While I was searching for my faulty climate control servo motors on the weekend, I noticed a brown cable with a cable lug located in the passenger footwell, near the heater.
After doing some research, I found out that this cable belongs to the auxiliary heating element Z35. According to the wiring diagram, it should be connected to the ground point (606) near the gear lever. However, I'm wondering why it's not connected there.
I located the positive terminal of the element in the driver's footwell and found that the connector is plugged in there. The cables from there terminate at the relay block, specifically relays J359/J360. The red/yellow cable leads to a red cable, and the two red/white cables are combined into a single red/white cable.
What seems strange here is that the fuses S276/S277/S278, which are actually intended for this purpose, are not present in the relay holder. The cables go directly to the relays. I couldn't find a fuse anywhere.
After measuring the open cable end against ground today, I found that it was actually receiving the vehicle's internal power supply voltage after about 10 seconds. This voltage remains present until the engine temperature, as indicated on the instrument cluster, reaches 90°C. This means a distance of approximately 30 kilometers at those temperatures. The wiring seems to be correct, at least approximately.

Since I absolutely do not want to connect a 1000W heater to the on-board electrical system without proper grounding, I have the following questions:
Why wasn't the mass (factory-installed) connected?
Why are the fuses (S276/S277/S278) missing from their designated locations?
Where might the fuses be hidden, if they exist?

The car is a:
Seat Ibiza, manufactured in 2001, model year 2002.
Engine code: ATD.

PS: The diagnostic code 7E6 for the electric auxiliary heater does not appear in the inspection report.

Greetings.
Jens.

Today, I found two 40A fuses located outside of the relay holder. The cable colors seem to correspond to the heating system.
Where could the third fuse be hidden?
In the wiring diagram, after the fuses, you will find the following connection:
A152 - Connection -5- (87), in the distribution panel wiring.
where can I find this connection?

Hello!
"Three fuses would surprise me. It involves a 300W heating element and a 600W heating element. This allows for the three levels to be switched using two relays."

Regards,
Brezelmann01

Hello,

I was mistaken; the fuse I found is only one. The black part in the middle of the fuse is a locking tab. According to the wiring diagram, this is fuse S276. The rt/ge cable connects to a red wire here. This is the fuse for the first stage. The other two stages are, according to the diagram, separately fused with S277/S278. Unfortunately, I can't find either of those two fuses or the connection A152 behind them. I would have to remove the entire dashboard to expose the wiring. I'll try to see if I can identify anything more by removing the body control module, the relay block, and the distribution box. That should be relatively quick.

Greetings.
Jens.

Hello!
"Three fuses would surprise me. It involves a 300W heating element and a 600W heating element. This allows for the three levels to be switched using two relays."

Regards,
Brezelmann01

Hello,

I have now removed the body control module and the relay holder and found the other two fuses behind them. Then I connected the ground connection, and sure enough, everything is working.
The initial questions remain unanswered. However, at least the car will now warm up quickly.

Greetings, Jens.