VW Golf IV: Engine Temp. -99°C, Climate Control Issue

HI ALL

I have to say that this is a great forum , and I hope to find help here.

Problem statement:
Dual temperature sensor 059 919 501 A, green, according to VW it is defective, but it is new and was purchased recently.
I once checked the values in the climate control system, and according to the display, the engine temperature was -99°C.
OK, I'm looking for an old temperature sensor and I've found one. However, the one that's installed is black (it's located on the flange where the glow plugs are, towards the splash guard). Is that correct? I tried disconnecting the connector and plugging it into the new sensor, but unfortunately, the climate control system still shows a motor temperature of -99°C.
Error memory is empty.
The car isn't going any faster than 180, but someone keeps hitting the brakes (it feels like they are).

Please help, I'm stuck.
1.9 TDI engine, 130 horsepower, manufactured in 2001.

Hello,

As far as I know, the black and green sensors only differ in terms of accuracy (the green one is more accurate).
You can use a multimeter to test the sensors. You should be able to find the expected values somewhere. Ideally, both sensors are faulty. In the worst case, you have a break in a cable or in the connector. A reading of -99° likely indicates a "lack of contact," I would say.
Take a look at the inside of the connector (the contacts) and the wires (on the outside). Perhaps it was damaged at some point while someone was working on the car. It's really awkwardly positioned back there.

You say the error memory is empty. What does the temperature sensor report when read out using the diagnostic tool, instead of through the climate control system?

Current VAG-COM versions would display a message in the relevant measuring block...

-99.0 °C = Not relevant/unused (e.g., in VW Golf/Jetta (1J))

...to display.

Thank you for the answers.

I still have a few questions.

Could the problem with the poor performance be related to the temperature sensor?
Were Black people used in construction projects in the past?
Can this damage the engine?
Is that correct: "The donor seat is located on the right side of the rear compartment, facing the splash wall"?

I can also feel a noticeable "dip" or "hesitation" at around 3600 RPM when accelerating.
Unfortunately, I can't make it to VW right now; I won't have the opportunity to go until in two weeks.

Engine: ASZ 1.9 TDI, 130 horsepower, manufactured in 2001.