byrdman454

Is it possible to replace the heating elements in the seats themselves?

I am getting power from the switch and through the relay, but no heat. I suspect the elements are toast. HAHA.

Any other suggestions?

Jfrahm

Yes, in fact there are some interesting new carbon fiber elements you might try:

http://www.sportsimportsltd.com/afcarseathea.html

-Joel.

Greg86andahalf

I used this kit as a replacement
http://www.seatcomfort.com/seatheaters.htm

Carbon fiber works much better than the original style.

Jim bailey - 928 International

As I recall three are 3 elements per seat ...backrest , seat bottom , sides of seat bottom ........not likely all three would be toast ....they sell for $150-200 EACH ! . Find the control unit 928 618 521 02 (fancy relay) check for power AND ground Porsche loves to switch the grounds and have constant power to the device ( interior lights for example ) Locate the plugs to the elements and check for continuity ....

Greg86andahalf

IF I recall correclty, The -DC part of the circuit runs through the seat bottom element , seat bottom thermostat, then to the seat bolsters and seat back. My seat bottom element had a break in it which killed current to any and all elements. The bolsters and back elements checked good.

It makes sense that the seat bottom element may fail first, since there is the most flexing there.

Greg

byrdman454

Can someone post some directions on how to get to the seat heater elements for replacement?

JE928Sx4.

You would have to pull all of the upholstery. I'd listen to Jim's advise 1st. Then I'd find the heating plug and feed some 12V current directly to the heating element next.

byrdman454

I checked for continuity. The backrest element is out on the passenger seat, but the seat bottom element showed good. It was the opposite for the driver's seat. Looks like I am stuck pulling the elements. I was hoping someone has done this job before and can shed some light on the pitfalls and lessons learned to make it easier.

Greg86andahalf

byrdman,

The pics show the fun and joy of bottom cushion element replacement using a carbon fiber element. The hog-ring clips need to be removed, there are steel rods and a ton of other hog-ring clips which need to be found and removed. Each bottom "panel" of foam has a bar and clips holding the leather down.

The carbon fiber element needs to be cut in order to allow the leather to be pulled down around each bottom panel. Not rocket science, but somewhat time consuming and you must remember that there is alot of metal seat upholsery hardware and the carbon fiber, where cut, has to be insulated from the metal as you can see in one of the last pics.

I used the hi-low switch which came with the carbon elements and put it in the blank cover on my seat controller as seen in the last pic.


Greg

byrdman454

Greg,
Thanks for the info!!!

Was there a reason why you did not splice it into the original Porsche seat heating wiring?

Greg86andahalf

Yes there was. The carbon fiber element has a different resistance than the OEM elements adn the carbon fiber needs less current to produce heat. The OEM does not have hi and low setting, the switch which came with the carbon fiber element does. Low is mostly adequate and hi will cook your butt. The bolsters and back OEM elements are wires with the carbon switch.

In a perfect workd, you would replace the bottom, back and bolsters with carbon fiber elements. The kit I bought would do the bottom and back, there is not enough to do the bolsters. I only did the bottom to start out. I may do the back while the seats are out at this time.

Greg

byrdman454

My bottom element is out on the drivers and the bolsters are out on the passenger. I was hoping to buy one kit and do both seats and splice it into the standard Porsche wiring.

Is there anything I can do to make the carbon fiber set work with the Porsche wiring?

Greg86andahalf

resistance matching would work. You couls also use the factory switch as the on-off switch, and leave the carbon switch inline and on low or hi, attaching it under hte seat with the other electrics. I would talk to the carbon element supplier about those two options.

byrdman454

Greg,
How much did you pay for your set of CF heaters? There is a set on eBay (2 carbon fiber heaters, hi/low switch, wiring harness and instructions) for $95. There are 10 sets available.

T_MaX

Byrdman thanks for posting the question, Greg and Jfrahm for coming up with some great info.

Greg they must have changed the switch set-up for the 89 MY.

For the 89, there is a rocker switch with a knurled **** in the center.

The rocker works as the on/off switch.
The knurled **** is for Temperature Control.

My car came with the drivers seat heated and at some point I would like to add it to the passenger seat, thanks again for the product links.