Anatomy of Ardic

Greetings from the non-insulated garage of my parents! I don't have any warm facilities to fix my car, so this will have to do. It was a nice warm day of -5 celsius when I decided that it is now or never (actually now or next summer) when I'm going to tear down the Ardic and see what's the problem.

Here's a nice post about removing and servicing Ardic. (Sorry, instructions only in Finnish).

Here's an explosion diagram of Ardic. Year is 2003, but seems to be identical to mine. Taken from Finnish Volvo forum, topic designated to Ardic problems..

Here's the big guy itself after removing the front bumper. Inferring from the rusted screws I would think this thing hasn't been serviced in years, maybe never during the 10 years this thing existed. There has been quite many previous owners and according to the owner history database, each of them had this car only little bit over 2 years.

After one hour of careful separation process in -6C, we can continue disassembly inside in room temperature! 

Glow plug, water pump and outer shell removed.

Testing the glow plug. Intact, as I suspected.

Inner shell shell removed, revealing chunks of soot attached to the walls 

Here's the combustion fan motor, working normally. Little bit to the left under the cap resides the flame sensor that is directed toward the combustion chamber. I managed not to take any pictures from right angle, but there was little bit of soot there as well, blocking the view of the flame and causing the main problem here. After some cleaning, the flame sensor reads ~8 Mohm when in dark and around 430 Kohm when teased with direct light from a flashlight.

Quite a bit of soot also under (actually over, since the unit seen here is held upside-down normally) the cup and the turbulator. There's a shadow under it too, but most of it is soot actually.

Here's the CPM. It's funny feeling seeing it now here, like meeting somebody in real life after you have spent weeks chatting online :)

We know each other so well already, so there was no need to be embarrassed. Let's take the cover off and look if there are any unhappy burned parts. None found.

Only after putting the whole thing together again and looking this image more carefully when uploading this picture, I noticed this burned looking solder joint little bit from the center to the direction of upper left corner. Weird, since the heater seems to be working now.  Maybe it was just the angle, light doing its tricks.

So, I cleaned the heater from all the soot and put the thing back together. Fingers crossed, I started the heater and behold, it works now! It seems that soot builds up as a result of imperfect combustion and eventually blocks the light/flame sensor. When this happens CPM thinks there's a problem with fuel delivery or some other functionality, and then stops the heater. Ardic does need service at least every two years, but some people service it annually, especially when there's a lot of short distance driving and the heater runs cold proportionally greater periods.

 I didn't touch the water pump since it seems to be working and I don't have any spare rubber parts should the pump need any of them changed after opening the thing to prevent leaks. Anyways, I'm going to buy a new pump next summer when I'm servicing this thing again, just in case. It's interesting to see how much soot buildup will occur during the winter months with my personal driving style and preferences. From there it will be possible to estimate how long a relatively safe service period would be. It would be possible perhaps to estimate this based on the voltage reading of flame sensor! Of course, this would require reaching a steady state, maybe after running the heater for one hour until all the temperatures reach equilibrium and then check the sensor voltage. The nearer it is to the 2.5 volt threshold (explained in previous post) when the heater is on, the more the there could be soot covering the eye of the flame sensor. I will have to check the reading soon when it is still clean.

UPDATE: The flame sensor voltage will fluctuate between 0.6 and 1.0 volts when the furnace has been cleaned. Boys, when it starts to climb over 2.0 volts near the 2.5V threshold, it's time to grab your wrenches and mops and start cleaning!