Maarten ---

I must refresh my memory. First, get kneepads or a kneeling pad -- you'll do much of this work on your knees!

Under the hood, clamp off the two heater hoses at the firewall. You can buy special clamps for this (inexpensive), or use "C" clamps and pieces of wood to bridge across the hoses. Pinch them tight enough to only stop flow -- too tight, and you might damage the hoses.

Inside the car, you only have to remove the left-side kick panel. The valve is located near the fire wall, on top of the hump. On left-drive cars, it's near the gas pedal.

Have several old towels ready -- when you remove the hoses from the valve, several cups of coolant will spill out. If you have the special clamp for hoses, try to clamp-off the hose from the valve to the heater core to prevent the core from also draining. You might be able to catch all this in a can. Try to prevent coolant from running onto, or under, your carpets -- it's a major source of rusty floors.

In the past, I have been successful using an old sparkplug to block this hose, preventing the heater from draining and making a mess.

Remove the hose clamps attaching the two hoses to the valve. Pry the hoses off the valve -- they can be difficult, so try not to damage the hoses. (Replacing the interior heater hose can be a difficult project.) Unbolt the valve from the bracket. Unscrew the little clamp holding the wire adjusting cable. With a screwdriver, pry the oval-shaped rubber plug (about 3 cm by 5 cm) from the duct, and pull down the (coiled) temperature sensing tube.

Remove the old valve.

Installing the new valve is doing everything above, but backwards. The rubber plug can be difficult to insert into the duct -- sometimes people glue or tape them in (I don't think it's critical). Sometimes a slight cut in one edge makes it easier to install.

Also, be sure the cable is adjusted so the valve turns completely off when you set the temperature at minimum. Otherwise, you'll always have a little heat coming into the car. I like to adjust it so it pushes the valve off when the temperature adjustment knob is about 2-3 mm from minimum position.

If you decide to use the newer valve, you must buy the modification kit from Volvo. It is a more difficult job, but there is a technical service bulletin with all the steps.

Be sure to remove all the clamps squeezing the hoses before you drive the car.

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