Does anyone know how to clear the DTC memory?

The A/C compressor is not kicking on at all on our E300. All of the sensors are giving readings.

Readings from climate control diagnostic
Code #7 - 06 bar
Code #8 - 89 - this is the temperature in Farenheit

The bar readings on my '97 are higher at 14-17.

It seems as so that there would be low pressure in the cooling system, but with everything off on our little pressure gauge the figure is high, in the red. When we checked my '97 it was on the border of red, but the pressure gauge reads in PSI, not bar.

There has got to be a simple way to clear codes on these.

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'97 E300
'99 E300