[flash]

ok - complete lapse in judgement - i'm also having a senior moment where i know i should know this, but for the life of me i am just not getting it

i am trying to install seat heaters in my blue car - i keep running up against the same problem though - the switch

the heaters are 2 settings (high and low) - i like that

but, the switches i keep finding are either ones with a rheostat in them or momentary 2 position switches

i don't want the ones with the rheostat

i like the 2 position rockers - the problem is the momentary part - yes, i am sure they are momentary - there are 3 pins on the rear - i energize one (which has a red wire still on it) and when i hit the switch one way, it sends power to one of the other pins - when i flip it the other way, it goes to the other pin - in both cases though, the switch goes back to center and the power cuts off

obviously there is a relay or something that is needed to trigger the heaters - so, my questions are:

what relay would i use that would allow each hot pin to activate the heater?

if i find a relay that does this, how do i shut the heat off?

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[SILVY968]

flash,

I think that what you need are 2 latching relays. Hook it up so that when you click the lo relay on it stays on, click it again and it goes off. Hook the other side of the switch to a second latching relay to energize the hi heat setting, pulse it once to turn the hi on, again to turn it off.
I do not know how the heaters are wired, but if it is 2 independent heater coils of the same wattage, this setup would give you 2 heat settings; otherwise it would give you 3 heater settings.
To turn the heat off you would pulse the lo once and the high once, that would drop off the relays and disconnect both heater coils from the B+.
"A latching relay has two relaxed states (bistable). These are also called "impulse", "keep", or "stay" relays. When the current is switched off, the relay remains in its last state. This is achieved with a solenoid operating a ratchet and cam mechanism, or by having two opposing coils with an over-center spring or permanent magnet to hold the armature and contacts in position while the coil is relaxed, or with a remanent core. In the ratchet and cam example, the first pulse to the coil turns the relay on and the second pulse turns it off. In the two coil example, a pulse to one coil turns the relay on and a pulse to the opposite coil turns the relay off. This type of relay has the advantage that it consumes power only for an instant, while it is being switched, and it retains its last setting across a power outage. A remanent core latching relay requires a current pulse of opposite polarity to make it change state."
Maybe...
Brian

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[banditsc]

How about one of these? http://www.sportsimportsltd.com/ilsehehirosw.html

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[flash]

silvy - thanks - yeah - that's pretty much what i figured - ok - now how the heck do i figure out which relay? lol - i have the switch number, so maybe from there i can find the relay through porsche

banditsc - that is the switch it comes with - i want a switch that fits into the rectangular switch spots

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[banditsc]

Ok, there are a bunch of them here, just look to the right of the column for on off on switches. http://www.action-electronics.com/switches.htm

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[Darryl]

You should be able to use the equivalent of the mirror select switch. It is "one way or the other"...not momentary. Don't think you'd need to go to the relay unless those things draw a lot of current.

Some of the seat heater kits I've seen come with the round switches that get installed on the side of the seat similar to the factory power switches, ie, a big round button with "ON" and "OFF". I'll be interested in what you come up with as I'd like to add heaters to the Coupe someday.

- Darryl

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[flash]

bandtisc- i'm really trying to keep an OEM look and use OEM switches - these are going to live right in the middle of the dash, one on each side of the HVAC controls

daryl - interesting idea about the mirror switch, as long as the center position is "off"

i'm also going to look into mounting then on the seat, but i am not hopeful - not a lot of room on these, and not in a good spot

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[biotechee]

BTW- the OEM set-up had a control unit for the seat heating system. A separate box (maybe a relay or something else) can be seen on the PET, complete with its own part number.

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[flash]

yup - don't need any of that

i am now just looking for a latching relay, since these heaters have their own control unit - that way i can use these switches

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[flash]

well, i'm closer

the relay i need is porsche part #928.618.521.00

lol - of course, they are back ordered everywhere on the planet, so i will have to find used ones

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[banditsc]

https://www.928gt.com/p-25948-relay--sea...85-95.aspx

Or if you want used and quickly, 928 International in Anaheim has them for $22.

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[biotechee]

That part number is refered to as the seat heater control unit, which I mentioned earlier.

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[flash]

actually, according to my phone call this morning with sunset, the later part number, which goes with the other switch, is called a "control unit", but the earlier one, the one that was in the 944, and which matches this switch, is just a relay

semantics likely, but that's what he said the PET says

either way, the problem looks to be resolved, once again, by pat's parts warehouse

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[gryphon]

Why do you need seat heaters in southern California? Was Al Gore wrong? [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

Tom

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[flash]

lol - no roof - top stays down all the time - contemplating removing it altogether

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