NJ964

Hey guys, I'm about to install a heater duct bypass on my '91 964 and came across something I wasn't too sure about. On the original duct, there are two vent tubes, but only a hole for one on the bypass duct. I know the distributor vent tube is what needs to be hooked back up to the new duct, but what is the other tube for and what are you supposed to do with it (cap it, reroute it, etc)? I attached a picture with both tubes circled to give a better description of what I'm on about.

Also, searched around the internet and didn't find much on this. This is the first bit of work I'm doing on the 964 and just want to make sure its right.

freedman

Rear light vent

Runs to the centre reflector, which is in turn connected to the corner lights by vent tubes

You can either put a second connector in your bypass or put a T piece in one of the tubes to keep both connected

hepkat63

NJ964, this is where I stopped too. I bought the heater bypass piece, fitted it and then realised I had a heap of issues afterwards.
1. Where did the other tube go (yes, I know what it did - vent the tail lights ... but do i drill another hole or fabricate up a t-piece)
2. There is a ballast switch with two wires on it that came off the old heater - what to do with that?
3. There was a heat sensor of sorts sticking through the tube
4. There was another sensor of sorts there too.
When I realised all this stuff now would not be hooked up - I kind of thought -what is the point of all this?
I then researched a heap and found that there were a lot of guys out there that just could not get this working (heat) at all - whilst others say that there is more than enough heat. I decided just to put it all back the way i found it and wait for more information. (then I stripped the bottom bolt of the heater unit putting it back too $@#$@#$)
So, I'll be interested to see how you go.
regards
steve

NJ964

Thanks for the replies,

From referencing other writeups and even the manufacturers install instructions, it doesn't seem like the tail light vent is a major priority since its never mentioned. I have not I seen any with an extra hole drilled or with a T either. I definitely don't want to drill into this nice, new carbon fiber piece, so maybe I will just punch a whole in the lower rubber connector and run it there.

As far as the electrical in concerned, I've read that the connectors just get zip tied out of the way. Then, if you want to retain fan control while running the heat, you need to jump the relay for the blower motor. Otherwise, the amount of heat blown in the cab is solely dependent on the main engine fan.

Steve, the main reason I'm switching to the bypass is that my blower motor gave out on me and a replacement is pretty expensive in comparison to the bypass. Also, this car isn't my daily driver so heat isn't my biggest priority.

I should be completing this today, so I'll let you know how it turns out and maybe post some pictures.
Thanks,
James

crg53

Hopefully someone can chime in with a link to the proper way to do the bypass, if not I can find it for you, but I am away at the moment, so you will have to wait until Sunday. It is extremely easy to do, and works like a charm.
PS. Found it, search for "rear heater blower problem? RS delete ?" Scroll down and you will see what to do.

warmfuzzies

Did the linked relay this morning, removed the other fittings, and mine works pretty much as others have described.

Heat, but a little slower pace than before, but it works.....

K

hepkat63

do you have the direct link to the fix please ? I searched "rear heater blower problem? RS delete ?" and it says no results found. I'm pretty stupid when i comes to searching these forums, can never seem to get what I need - I just click the search this forum and then put in (exactly) "rear heater blower problem? RS delete ?" and no results?

hepkat63

Did some more searching and there are a couple of threads that reference someone doing this in a 993 and comments stating that in a 964 it is different and to jumper a wire.

I think I found it at thread 44 here: https://rennlist.com/forums/964-foru...ss-tube-3.html

Sure would be really good if someone could put this in the 964 DIY section as it is pretty popular and it appears that if you have Climate control there are a few extra steps you need to take (and not just zip tie the wires up and you're done) if you want to do the job properly?

JasonAndreas

How much did you pay for the bypass? The rear blower motor is less than $200USD.

crg53

Jason is right, you buy a new blower motor for less than $200. I am on my iPhone right now and don't know how to add the direct link, will post it here tomorrow.

NJ964

Well I got the bypass installed today.

I just removed the tube for the tail light vent (you can see it in the second picture). I figured it was more for venting air/moisture out rather than forcing air in, so it is not necessary. I will keep an eye on it and if condensation begins to form I will probably connect it to lower plastic tube that the bypass slips into.

I did not get around to the relay wiring part of the install yet, but have read a few write ups on it and it seems fairly straight forward. Even without the fan control, the heat was fine and it was in the 30's tonight in NJ.

Also, where are you guys finding the blower motors for less than $200. Other than second hand, the lowest I saw was twice that. Pelican is selling them for almost $500. Either way, I paid $275 and it was worth it. The bypass cleans up that area of the engine bay a lot and the carbon fiber is pretty trick.

Next is to fix that droopy insulation and maybe find a cleaner, high flow air filter to clean up the other side.

Thanks,
James

NJ964

Here's a link that talks about the modifying the relay, including a nice picture from crg53.

My questions now are, where is this relay located and did you need to change the resistor. It seems like some people did and some didn't with about the same success. Since, the blower motor is gone I don't see why that resistor is even a factor and it seems like just jumping the relay would work fine.

https://rennlist.com/forums/964-foru...er-bypass.html

kos11-12

Interesting wiring ,
Steen , did you experience any drain of the battery, are your fans working like before , are they slitly lower on power ,
I use Anto / babalouie method with the wire connected + coil and a 5amp fuse.
I have No drain but my fans are lower on power , I have to turn to 3 to get 2 for equivalent fan speed ....

warmfuzzies

Hmm, my My91 has only one of the jumper wires fitted, and the whole system works fine, it runs left to right looking at the picture. But I dont have A/C, would that impact the mod for others?

https://rennlist.com/forums/964-foru...ss-tube-3.html

K

hepkat63

I have A/C as well - so is the wiring the same?