Hi i beleive on the resister pack there are soldering points on it and they tend to braek up check to see if the soldered points are all ok and not cracked or broken i hope this help all the best DonaldI really need help with a similar problem , the heater on my renault espace suddenly started blowing on full last week and wouldnt adjust at all , it even stayed on when I turned off the engine so I had to disconnect , bought a new switch for dashboard and when I switched it over heater now turns off and on but only works on first speed , not sure whether this is resistor as previous posts suggest resistor fault results in heater only blowing on full speed, please help , thanks.
Sorry its taken a while to reply but to the pointIf the resistor pack goes you only lose the lower 4 settings - the fast setting still works. The multiplug on the outside of the fan housing is a troublesome area. Unplug both halves and look inside for signs of burning. The most reliable way of fixing is to hardwire the connections or use bullet type crimp connectors.