Note: The components of the system vary slightly according to engine type. The following procedures depict one of the more common systems, but all are similar.

Vacuum switch
Removal
1 Remove the air cleaner housing-tocarburettor inlet duct.

2 Bend up the tangs on the switch retaining clip, then remove the clip, along with its seal, and withdraw the switch from inside the duct.

Examine the seal for signs of damage or deterioration, and renew if necessary.

Refitting
3 On refitting, ensure that the switch and duct mating surfaces are clean and dry, and position the switch inside the duct.

4 Fit the seal over the switch unions, and refit the retaining clip. Ensure that the switch is pressed firmly against the duct, and secure in position by bending down the retaining clip tangs. Refit the duct.

Air temperature control valve Removal
5 Disconnect the vacuum pipe from the air temperature control valve, then slacken the retaining clips securing the inlet ducts to the valve.

6 Disconnect both inlet ducts and the hot-air inlet hose from the control valve assembly, and remove it from the vehicle.

Refitting
7 Refitting is the reverse of the removal procedure, noting that the air temperature control valve assembly can only be renewed as a complete unit.