In order to avoid filling the foot well up with any more coolant - I disconnected the hoses inside the engine bay and then blew inside one of them to force all the coolant out (watch you don’t get it in your eyes).

Then, remove the single screw and pull the pipes out. The o-rings were very brittle and couldn’t even be removed without breaking.

I had to put quite a few patches on the dashboard, as the lower part was broken in places around the centre console. I’m guessing that someone has had a go at fixing the o-rings and gave up.

Feb 2011: Heater matrix O Ring Replacement Part 3

Hevac Manual FAN blower speed not working.

Whilst the car is in bits I’m going round checking and fixing other items. A problem that I noticed when buying the car was that the dial to manually set the speed of the blower fans didn’t respond or do anything. The unit would stay in “Auto” mode all the time.

As I’ve got my Faultmate Extreme diagnostics I was able to get onto the ECU and start investigating the problem.

I read the fault memory, which only produced codes about the blend motors - So next I used the outputs section of the ECU to force the blower motors:

Both fans responded to commanded speeds, well the nearside one did once I reseated the relay in the main fuse box under the bonnet - its suffering from the common ailment of burning the contacts.

So with the fans able to respond to speed commands I knew the problem was more likely to be within the actual hevac ECU. I suspected a dry joint, so I decided to take it to bits to investigate.

With the front panel removed a little metal wiper fell out - I could see that it had come adrift from the rotary selector. So I melted it back on with a soldering Iron and then put some hot melt glue on for good measure.

Feeling proud of myself I put it back together and tried it in the car - but it still didn’t work. So I took it to bits again and bent the wiper out so it made a better contact with the PCB - this sorted the problem and now I have manual blower control back again. Simple fix!

Blend Motors

Time to check out the fabled P38 Blend motors.

Using the Faultmate I pulled up the diagnostic codes for the HEVAC and it was showing blend motor faults. The faultmate has the ability to force the blend motors to any position and also show the feedback from the actual motor. My left and right temperature ones were working fine - but the top air distribution one was only partially working and seemed to be struggling.  

Stiff Flaps (car, not wife)

Whilst the motor was off the heater unit I noticed that the distribution flaps were very hard to move - hence why the blend motor was reporting that it was stalling during calibration.  

A little googling around and I found some threads about it. So I jammed a screwdriver in the gap and sure enough the top distribution flaps moved much better.

As described in the thread, remove the bolts holding the front of the heater to the metal work, remove the clips holding the two halfs together and then force self tappers into the heater unit.  

Fooking crappy french Valeo junk - I think I will have to amend my Lucas prince of Darkness page to include the “Valeo heretic of heating...”

Inspecting a blend motor

Here’s how to open up a blend motor without all the gears dropping in a pile in your lap (Go on, ask how I found out..). You are looking for stripped gears - mine were fine, but the motor was weak due to it labouring on the stiff flaps (ooo-er missus)

Couldn’t be bothered with cleaning the brushes, It will be replaced with a NEW unit, not some other worn out 2nd hand part. When putting it back together make sure you align the two arrows.

I removed the distribution blend motor from the car and thought I would see if it could go to any commanded position without it having to actually move anything.

This approach is only valid if you remove the motor from the heater unit AFTER turning the ignition on.  Otherwise what seems to happen is that during the power up, the motors just run to the end of their travel, which is actually far more than the travel when attached to the actual heater unit. I didn’t realise this until I removed one of the perfectly working temperature blend motors and noticing that it now started reporting problems. As soon as I put it back on the heater the problem went away. (Abridged version of pissing about for 2 hours).

So you are sort of in a catch 22, on the car it stalls and off the car it travels too far!