This thread got me wondering about the state of my heater. The need for a heater, here in Arizona, is not that great, so I hadn't given it much thought. As it turns out, my 30A heater blower fuse was blown. I put in a new one, only to have it blow when I engaged the heater. I swapped the heater relay with the AC relay, and blew another fuse. Based on what I've read, my heater blower is gone? Has anyone replaced theirs? How long did it take? I checked Carnewal, but it didn't look like they carried it. Any Rennlist sponsors that do? Suncoast? I'll check there.

Thanks for any input on changing the blower

-John

 

Hi John,

<a href="http://www.pelicanparts.com/catalog/shopcart/911L/por_911L_exhaus_main.htm" target="_blank">Pelican Parts</a> (Rennlist sponsor!) has the "engine compartment blower motor" for the reasonable price of $125. For this amount, I presume this is the motor only, not the entire assembly.

Going out on a limb .... Vertex (let your conscience be your guide ) used to sell a "C2/C4" rear heater motor for $99. But, it's no longer listed on their on-line catalog. Also, their part (if they still have it) may only fit a 964, though I bet it will also fit a 993.

Back to Pelican Parts .... there's a nice write-up on replacing the rear heater blower, albeit for a 964:

<a href="http://www.pelicanparts.com/techarticles/964_blower_motor/964_blower_motor.htm" target="_blank">Replacing Rear Heater Blower on a 964</a>

 

Okay, I was reading the blower replacement DIY I linked above, and Tom S. says the entire blower assembly was $115 from Pelican Parts. So, I'm guessing the current price of $125 is for the entire assembly. If so, that's a bargain (in Porsche dollars, at least).

 

Hi Randall,

You probably realized I'm an elictrical-systems-ignoramus. So here's what I know: when the car was PPI'd they found this voorschakelweerstand to be defective (could tell from OBC ?). To replace it, the mechanic removed the driver's side headlight to replace a disk-shaped object (a little bigger than a 1$ coin, and about 3/4 " thick), and told me that these things very regularly break down. Apparently, there's a lot more that can cause blower failures. I hope you diagnose it soon. Good luck, Barney

 

This morning I tried what Randall suggested, I could not hear a rear blower (I assume the rear blower is in the engine compartment?). I wasn't sure which fuse was for the rear blower, I looked at all four fuses and they looked good. Maybe its a relay?

What should I try next? <img src="confused.gif" border="0">

 

Barney--that's the ballast resistor for the A/C condenser fan (or blower). Different blower . Anyway, they do fail quite often. And, they are a pre-resistor of sorts. To run the condenser fan in slow-speed, 12V is first passed through the resistor to drop the voltage. In fast-speed, the resistor is bypassed.

Tom .... yes, the blower is in the engine compartment, on the left side. Looks similar to the one shown in the Pelican Parts DIY link above, but with different ducting for your '97.

According to my shop manual, the rear blower fuse should be #42 on your '97, if you can see the number. You can test the fuse using the tester in the luggage compartment fuse box.

The rear blower relay is the same one used on the A/C condenser and oil cooler blowers. You might try a swap into the rear blower position. In addition, you can verify a relay is good (at least its slow-speed switch) by placing it in the A/C condenser plug, then turning on the A/C, ignition on. The condenser fan should run continuously with the A/C on.

Oh, yeah, one more thing you can try. Simply unplug (electrically) the rear blower's temp. sensor (it sticks into the ducting), ignition off. The rear blower should start in slow-speed, if the fuse and slow-speed switch on the relay is good.

Good luck!

Edit 12/19/02:

While helping someone diagnose their poor heat, learned something. His rear blower operated fine when heat was commanded by the temperature control ****, but the rear blower didn't start when the temp. sensor was unplugged, ignition off. Text from my e-mail to him:

**************
"I think your blower/sensor is fine here, and I've learned something. To be honest, a few other people have 'failed' the disconnect with ignition off test, with otherwise okay systems. Went out to my own car a short while ago, and I'll be damned if disconnecting the sensor didn't start the fan. Now, I and others have done this several times without trouble. Took the car for a drive, bringing engine temp. up to close to the 8:00 position. Disconnected the temperature sensor again, and after about a 5 second wait, the rear blower fired up. So .... apparently, the engine must be warm for this test to work. I guess my engine was warm the other times I've tried this.

I'll add that nowhere in the shop manual does it say that disconnecting the rear blower temp. sensor will cause the blower to run in slow-speed. Just like it doesn't say that disconnecting the oil cooler temp. sensor will cause the oil cooler fan to run in fast-speed. Purely empirical observations.

Considering that your own car has already passed the temperature control **** tests, the rear blower temp. sensor plug test doesn't tell you much. But, feel free to try it again with the engine warm."
****************

 

Randal, thanks for all the help! <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />

I ordered a new blower motor and will wrestle it in this weekend. Should be a fun project. The extra heat should extend our top-down driving season.

-John

 

Sweeet!

Just finsihed installing the new blower motor. The heater is now overpowering. I can't wait to drop the top on a chilly night and blast the heat! Thanks to everyone for their help! <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

When I pulled the old blower motor, the fan was very difficult to rotate, the new one spins quite easily.

Time to wash the car!

-John

 

That's great news. Glad to hear it!

Curious ... did you buy the blower from Pelican Parts? Was it the entire assembly?

I have an Excellence magazine road test on the (then) new '90 C2, where the author describes the heater blowing strong enough to chap your eyeballs. It really is a powerful system. I also like the way it heats up so quick on a cold start, not having to first heat up coolant like a water cooled car. On a crisp, cold morning, you can't get heat inside the car too soon.

 

Randall G -

to answer your questions, yes and yes!

I ordered it from Pelican for $125 and it was the entire assembly. I just removed the old one and swapped it with the new one. It was pretty painless, took about an hour.

-John

 

I haven't had a chance to cfully check out my system yet but I wouldn't be surprise if I will need to replace system. BigBadDa how about a DIY?

 

Hi tom i was following your tread because i had the same problem.
The 2 links Randel G left at the top of the page
are very useful to identfy the servos and test them.
there are 3 of them under the bonnet
1/ pull off the rubber strip behind the fuse box take the plastic cover out of the way.

2/ there you will find 3 black servos on the left middle and right with plugs attached.

3/ unplug the plugs from the servos one at a time and use a + and - current to pins 4 and 5
I think they were the top 2 pins

4/ reverse current + and- to turn servos the other way

this will open and close flaps to the windscreen and footwells and let you know if your servos are working.
If they are working then its probably a ccu problem which was my problem.
I had a go at fixing it with a multi meter and
found a damaged circet and repaired it.
I am also a complete beginer and never repaired anything like this before. good luck!

 

Hey Tom97C4S -

I used the DIY that Randall posted...

Replacing Rear Heater Blower on a 964
<a href="http://www.pelicanparts.com/techarticles/964_blower_motor/964_blower_motor.htm" target="_blank">http://www.pelicanparts.com/techarticles/964_blower_motor/964_blower_motor.htm</a>

The 964 DIY makes it sound harder than it is. They had to modify the new blower (a 993 part) to fit the 964. All I did was remove some of the black ducting on the left side of the engine. It is covering the blower motor. Then there are 3 hex nuts and 3 phillips screws to undo. Then you can remove the old blower and replace it with the new. I had the fuse pulled so that the unit was not receiving power. You might be extra cautious and disconect the battery also, but I didn't. Be careful not to drop any nuts or screws down into the engine area. Have fun!

If you have any questions, feel free to email, it was very easy and I could pretty much talk you through it.

-John

 

Thanks guys I will try to check it out more tonite and will post. <img src="graemlins/wave.gif" border="0" alt="[byebye]" />

 

After reading this great thread a couple of times I just went out and put my car through the various checks and am very happy to say that everything worked just fine! Living in Orlando, I had no idea if the heater or defroster function worked since I checked it at purchase some years back.

Thanks to all for another enlightening topic.