AC Drain Pipes

Last update:

08/03/2005

Ford Scorpio 95+ Air Conditioning Drain System

All automotive air conditioning systems produce condensation as the incoming exterior air is cooled. This makes it a desirable system to use in the winter to demist the vehicle. However this condensation must be removed from the system to prevent undesirable effects and it uses drain tubes terminating in a valve to do so.

If your Scorpio exhibits any or all of these following characteristics, it is advisable to check the drain system of the Air Conditioning system as the valves and drain tubes can become blocked.

	Damp Carpets in the passenger or drivers footwell.
	Misting of one or both sides of the windscreen, more noticeable when the car has been standing overnight and you start up in the morning.
	Unpleasant odours in the cabin.

Dirt trapped in the drain valve

Basic Component Overview

In the centre of the engine bay to the rear of the engine you will see the top of the Evaporator Housing; this contains the Blower Fan and Motor and the Evaporator Core. The Blower Fan pulls air in from the exterior of the vehicle and as this air is blown through the Evaporator core, condensation forms on the Evaporator fins and the water droplets fall to the bottom of the Evaporator Hosing. This is because cold air can carry less moisture than warm air.

Click here for an Exploded View of the Evaporator Housing

Click here for a concise & detailed description of an Air Conditioning system

With reference to the Exploded view, it can be seen that the air then flows through the Evaporator Core and exits the Evaporator Housing via slots at the rear. Also on the left and right, at the front of the Evaporator Housing, drain pipes can be seen. You will notice that the housing is moulded to form a slight incline for the water to run towards these drain pipes. At the bottom of these flexible Drain Pipes, one way valves are fitted. These consist of a rubber diaphragm and when the Blower Fan is running the suction developed in the pipe causes the diaphragm to seal the pipe and hence not allow any nasty odours from the engine bay to enter the cabin. When water builds up in the valve it forces the diaphragm open and can thus escape. It is common for these valves to become blocked with residue formed from the condensation and general air born particulates and if (when) this happens the water cannot escape. This forms an effective humidifier and causes the air blown into the cabin to be of high humidity. Also water will eventually collect in the ducting and run to the lowest point, this being the footwall.

24 valve engine, location is the same for all models

Removal & Cleaning of the Valves

WARNING: Ensure the engine is not running and that it is not hot!

Locate the Drain Pipes as shown. The valve is removed by squeezing the end of the pipe and out it pops. Prise out the red rubber diaphragm and clean it out with hot water and detergent. Ensure you replace the diaphragm correctly, so it is all the way into the plastic pip at the centre of the valve. You can check the pipes are clear with a pipe cleaner etc, but they don’t tend to get blocked up. Refit the valve, ensuring it’s located securely back into the pipe. Then clean the other remaining valve.

NOTE: AT least one early 24V Scorpio has been seen with only one valve fitted - on the nearside. There was absolutely no facility for a pipe on the drivers side of the bulkhead. If you have one of the first Scorpios do not be surprised if you can find only one.

Unpleasant Cabin Odours

Air conditioning systems require periodically cleaning to remove bacteria that can cause bad odours and possibly allergic relations. If water has formed and entered the ducting system it is likely that you will need to treat the system with an Antibacterial Deodoriser. These are usually available in the form of an aerosol spray that is discharged into the air intake. It's safe on the Scorpio’s leather and synthetic interior materials.

WARNING: Always follow the manufacturers Health and Safety Warnings on such products.

The Forte product is one of the easiest to use, as you only need to discharge it into cabin and the recirculation system ensures that it’s taken into and distributed throughout the ducting system.

“The treatment contains a powerful antimicrobial agent, which cleanses the air conditioning unit of any mould and fungi that have become trapped deep inside the system during periods of non-use, and eradicates the type of bacteria that have been known to cause car occupants allergic reactions and asthma-like symptoms”.

“The dual action treatment entails running a vehicle's air conditioning system on re-circulate and leaving the can of treatment fully activated in the front passenger footwall, to automatically discharge into the passenger cabin. The normal air conditioning setting is selected for a further five minutes. As a result, mould, fungi and bacteria are eliminated and bad odours are neutralised, leaving a fresh apple fragrance in the car”.

http://www.forteuk.co.uk

Also Halfords stock the highly effective Wynn’s product. With the Scorpio this requires directly injecting into the evaporator core, having removed the clips and the pollen filters first, with the windows open, A/C to off, recirc on and fan set to full.

More details on the Wynn's product available here

Injection of cleaner straight in to the Evaporator Core