Bad ground or overheating?

While driving and stopping in traffic jams, with the air conditioning “off”, the coolant temperature remains at level N.
When I turn “on” the air conditioning, after some time the temperature rises by 1 dash. And so it stays, even if I turn off the air conditioning.
Only need to turn the ignition off and start again and the indicator is again on N.
Auxiliary electric fan is functional but in this situation it does not work. new viscous coupling.
Is it overheating or bad grounding?

Thermal switch for fans maybe not behaving?

Everything is functional, in 1990 there are no 2 electric fans. The engine fan has a new visco clutch, the electric fan works properly. The thermal switch I checked, working.

Sorry, I have a 94, keep forgetting not all cars are like mine!

good luck with you problem!

Hi, check that the air flow through the radiator matrix is not partially blocked, all kinds of debris can accumulate between the fins, especially in the space between the A/C condenser and the radiator. I’m fairly sure the temp gauge reacts slower to a drop in temp than it does to a raise,
have you tried a fast highway drive to see if the gauge drops back to N due to the extra airflow through the rad ?

I washed the radiator with a pressure washer and flushed the system with a descaler. I haven’t checked the space between the coolers yet.
Generaly driving on the highway cools down to N but it takes a long time.

Today I was driving and it was N, I stopped to refuel. After starting the engine, he showed N + 1 and stayed until I got home.
Under the house I turned off the engine and immediately turned on the ignition and it was N instead of N + 1.

Another thing to check is the flaps on the shroud, are they nice and flexible or have they turned to cardboard? If the latter just get some neoprene sheet and replace them.

From that description I would say the temp gauge is working correctly and your cooling system for whatever reason is occasionaly running slightly hotter than normal. Most likely when you switched off for gas the build up of heat has caused the gauge to move to the next level, then by the time you arrived home had cooled enough for it to return to the N mark. Switching the ignition off and on has reset the gauge without having to wait for it to respond gradually to the slight drop in temp.
I’m not familiar with the 90 models so maybe somebody else who has one will respond, but I was under the impression the electric Aux cooling fan kicked in automatically whenever the A/C was turned on ? If it wasn’t like that from the factory I know a lot of owners have altered the wiring so it works in this way.

I regenerated the flaps.
The auxiliary fan turns on only at 95 * C at the bottom of the radiator, so it does’nt work immediately after turning on the air conditioning.
I do not know if there are acceptable fluctuations in temperature 90 * C <-> 95 * C when the air conditioning is working, or rather a 30-year cooler is not working.

The temperature indicator on the board is not an analogue indicator, but a stepper motor controlled from a microprocessor. Then the microprocessor reads the indications from the temperature sensor and drives the indicator, hence it may delay in response to changes in the readings?

I jumpered my Aux fan to start with the Aircon.

You had similar symptoms or did it preventively?

For my information what temperature is represented by the N on the gauge? And the wide mark halfway between N and H?

N -> 90 *C
N + 1 -> 95 *C (auxiliary fan start)
N + 2 -> 100 *C (wide mark halfway)
N + 3 -> 105 *C
HOT -> 110 *C