Thread: Heater O-ring and blend motor

Hey! It worked - a little break did allow progress to a previous sticking point. I still havent got the vertical duct out, but I did give my self much more room by removing the lower horizontal duct.

I went back after a break and built this tool to get to the screw through the drilled access hole in the inner panel:


It wouldnt work with a std phillips bit or a posidrive bit, but then did work with a fatter phillips head bit. The oring clasp screw wasnt even that tight! Happy.


It took a minute to work the heater pipes back from the hater core face. In the end turning each one along its axis made it work its way backwards rather than yanking on both at the same time. Not much coolant came out.


The big question is: Why does my existing oring look like this (below)?! The oring didnt come off with the heater pipe, it stayed in the heater core face and I had to pry it out. Is it a 10 year old one that has changed shape, or is it a different brand of heater core? They don't appear cracked and they are flexible. Maybe they should be reinstalled. I should also mention, that I havent noticed any leaks at all, my main purpose was to get to blend motors.

After a long day of frustration, its not over. When I refilled the coolant and restarted - I had bad leaks at the newly installed orings I tried to tighten the screw further to no effect.

I have removed the screw again and noticed that the metal heater pipes are "keyed". See images below. The pipe has a notch in it and the accepting hole has a "key" in it. This means that the pipes can only go in in a certain spot. I dont see why.

I will again try to insert the pipes, with the orings held neatly but this time taking more care to orient the pipes in line with the notches. If this doesnt work, then I am afraid that the orings are too different to the originals? See image in previous post.

Wish me luck. The wife is getting cranky and RR WAF (wife acceptance factor) is declining.

I can confirm that the orings can be done without cutting the duct. It (the vertical duct) is moved forward (toward the engine) to provide access to the oring retaining screw and then backwards (towards the boot) to provide hand access to the pipes and orings. Often I used my right hand on the oring end and my left hand to feed the long screwdriver tool to the screw, and used feel to join the two as its hard to shine a light and direct it by eye.

Originally Posted by glenhendry

I tried to tighten the screw further to no effect.

Be careful & resist the urge to tighten the screw too much. You can crack the heater core & that's the last thing you want to replace as the car is built around it .

Well its finished. I did NOT manage to get the temp blend motor out, but I did replace the heater o-rings and stop them leaking on the second install. I took care to line up the notches and ensure o-rings were properly seated during insertion - NOT an easy task. I was careful not to overtighten, but I did put some weight on it.

I would be very keen to hear if others old o-rings were so mishapen as per the photo below. It doesn't even look like they could have ever be round!?

I still have no heat from HEVAC. The pipes entering the heater core are hot. It must be either that blend motor or maybe that sensor which measures the heater core's incoming water temp.

Originally Posted by glenhendry

I can confirm that the orings can be done without cutting the duct.

I didn't cut any ducts when I did mine.

Originally Posted by glenhendry

My HEVAC gives good cold, but not heat, so (thanks to this) I suspect the horizontal blend motor....

But I did write some of that page.

I have noticed a discrepancy between the revered RR.net pages and the RAVE. Which one do I believe?

This page (from RR.net) says the top blend motor is distribution and bottom one is temp. However RAVE says (Overhaul manual, Section 80 (Heating and Ventiliation - Page 8)) that the top one is temp and bottom is distribution.

I think RAVE is wrong. Because in the image from RAVE below, blend motors labelled 9 and 10 are both horizontal and affect the dual zones of the climate control. It makes sense that they control temperature, as the distribution (windscreen, face, feet) cannot be effected seperately between the zones (driver and passenger).

The reason that this is important to me, is because my heat doesnt work despite having a hot heater core. I can get to the top blend motor, but not the bottom, so if RAVE is correct, then I can get to it more easily.

- why dont these embedded pics work for me

It was my understanding that all three blend motors come on a single harness, so to do one you have to replace all three. when i did mine i ended up cutting the vent into three pieces and just blocking the hole with some 100 mph tape. the back no longer gets air but i don't sit there so it doesn't bother me. total time took about 6 hours start to finish.

good luck its a mongrel of a job.

You can purchase the Blend Motors as Single Units which you then splice onto the existing harness to replace 1 at a time as required. Only really useful if the Right Hand Side is the faulty one, because otherwise you'd be better off ripping the dash open and replacing them all at once.