AC selector switch rebuild

[MML]

Hi guys,
I just spent an hour removing and rebuilding the AC selector switch as it was hissing like crazy. There was always a pitiful amount of air coming out the vents, so I figured I'd do it now and get it over with.
I pretty much followed the instructions, (removed and replaced it without removing the console), put everything back together, fired it up... and it still frickin' hisses. Only not as much as before, and there's a good amount of air now.

Is this normal?

My arm hurts like hell after all that faffing about and I don't particularly want to take the switch out again!

[DMCMW Dave]

Hi guys,
I just spent an hour removing and rebuilding the AC selector switch as it was hissing like crazy. There was always a pitiful amount of air coming out the vents, so I figured I'd do it now and get it over with.
I pretty much followed the instructions, (removed and replaced it without removing the console), put everything back together, fired it up... and it still frickin' hisses. Only not as much as before, and there's a good amount of air now.


Did you lube the rubber diaphragm?

You may need to replace the rubber part if it seemed hard.

[MML]

Did you lube the rubber diaphragm?

You may need to replace the rubber part if it seemed hard.

Yikes, I left that bit out - yep I put the new rubber bit in, sprayed it with a silicon oil spray. I reused the old clip as it was fitting more securely than the new one in the kit.

With regards to the oil spray, should you use a little, or a lot?

[jawn101]

Does your car have the rubber "nipple cap" on the back where all the hoses connect? If so, did you ensure the cap is securely attached to the back of the switch? It could be a very easy fix if that just needs to be pressed on a little tighter.

[MML]

Does your car have the rubber "nipple cap" on the back where all the hoses connect? If so, did you ensure the cap is securely attached to the back of the switch? It could be a very easy fix if that just needs to be pressed on a little tighter.

That's this one?
http://store.delorean.com/p-7758-vacuum-hose.aspx

Yep, it does... it took a good 10 minutes trying to get it back on, only working by feel. I though I had it on fully but I can double check tomorrow! It's kinda hard to see in there but I'll try my best.

[MML]

I had another poke around in there and I'm pretty sure the cap is on tight!

There's one other thing I did notice. If I turn the fan to number 4, the selector to defrost, and the temperature to cold, it blows quite a lot of air from the window vents. However if I do all the above but this time put the temperature to hot, very little comes out the vents, and a lot seems to blow out around my feet! What's going on there?

[jawn101]

That doesn't sound right. In defrost mode (N:01:09 in the service manual) "Vacuum is supplied only to the screen flap, and the current to the fan speed switch. Heated air is supplied to the screen vent with a small bleed off to the footwells and, via the bridging duct, to the door vents"

I'd suggest running through all the test positions in the beginning of section N and seeing if the system behaves normally under any conditions. Determining the ones where it works properly vs performs abnormally will help you determine what's wrong.

Section N attached for your reference...

[MML]

I found the problem! This sums it up:
http://www.dmcnews.com/Techsection/heatairleak.htm

There's a hole in an air box under the dash that is plugged with a bit of foam. The foam had come loose and air was getting out into the footwell! I covered it with a lot of duct tape, and that seems to have improved things. I think I might have missed a bit as there's still a slight draft down there. It was a nightmare to reach in to it, so I'll get it at a later date!

Thanks for the input anyway guys!

[jawn101]

Awesome. I completely forgot about that, but I've read it before and even did it in my own car. It wasn't too awful to accomplish if you pull the driver's seat and get a head-mounted flashlight. I pull my seats out to do just about everything these days, it makes a world of difference when it comes to working inside the cabin.

[MML]

Awesome. I completely forgot about that, but I've read it before and even did it in my own car. It wasn't too awful to accomplish if you pull the driver's seat and get a head-mounted flashlight. I pull my seats out to do just about everything these days, it makes a world of difference when it comes to working inside the cabin.

I haven't been brave enough to remove my seats yet... although the carpets could do with a good thorough clean, so I suppose I'll have to!

[jawn101]

Oh man, it couldn't be easier. Slide them all the way forward so the rails don't bind on the seatbelt mount. 4 13mm nuts under the car - can reach them easily without even lifting it an inch. Seat lifts out. Good luck with the airbox!