928worldwide

Rog Keeps them all, in the weissachs- so he can wear a fresh pair with each different 928 car he has.

Rog,
How about it buddy! You're the best..... If anyone doesn't know, ROGER IS THE MAN FOR NEW 928 PARTS!! Friendly , Classy service.... and answers to most of your questions. Roger walked me through my first timing belt job after the bandits in the Neighborhood realized I wasn't a pushover.... I need to buy one of those Porken timing rigs...what a great tool!!! That car ran soooooo much better after the timing job. -Dr. Tom are you out there??? I miss that car...

Brett928S2

Hi

I dont know precisely WHY changing the inside temp sensor worked...but it DID!

It was a couple of years ago, but from memory...the symptoms were...the blower ONLY worked in the defrost position at the end of the slide....and would only give one temperature...and no adjustment of temperature worked.....

So someone told me it was the temp sensors...so I changed the easy one (outside in the alternator hosing)....and of course that didn't work..... so I then tried the blowing smoke at the inside sensor with engine running and sliders in middle....it DID NOT suck air in as it should have.....so I changed the sensor and fan unit....and all worked again

From memory I had to strip most of the centre console and radio surround and the sliders surrounds and it was STILL an absolute pig to do.....again from memory there was one bolt that was EXTREMELY hard to remove that holds in that sensor/fan unit...I remember skinning my knuckles BADLY lol

But it DID work, although as I have said, I don't know precisely why....

I think the sensor/fan unit was around £35 (Uk pounds)

If you are going to change it...replace with NEW......you do NOT want to ever have to do it twice lolllll.

All the best Brett

Alan

OK - most likely is a need to swap the blower relay for a new one - try the horn relay as an alternate

Otherwise the blower switch connector may have fallen off (on the AC head unit).

Alan

the flyin' scotsman

Did you do any further tests to the inside sensor? after it was removed.

Tony..........replace the relay with a known good; as Alan suggests the horn relay and many others are same. Double check the wiring to the new resistor pack.

Brett928S2

Hi

Nope sorry I didn't bother.....

Seemed simple to me at the time....

Old blower/sensor....no work....

New blower/sensor.....all working again....

I.E the blower started working again and I had temperature control back fully....

As it wasn't sucking smoke, I would suspect it was the little blower fan , but not sure....

All the best Brett

WallyP

Tony,

Get your wiring diagrams out, and look at Page 97-221, labeled "Wiring Diagram Type 928 S Model 85 page 4".

In the box in the center of the page, in its lower left corner, you will find a box labeled "FRESH AIR BLOWER" - this is Relay X, the blower relay. There are four numbered terminals on the top of the relay.
30 is the power input to the relay from Fuse #17
87 is the power output to the "Blower Switch" at the top of the page.
85 is the ground terminal for the electrical coil that operates the relay, hooked to MP V (Mass Point, European for ground connection, number V)
86 is the power to trigger the electrical coil that operates the relay, fed from the "AC-Control Switch" at the top left of the page. This is usually called the control head for the HVAC system.

To start actually finding what is wrong with your blower:
- Find Relay X and remove it. Look carefully at the diagram on the relay, and identify the four terminals listed above in the socket for the relay. Make sure that you know which is which.
- Using a 12 volt test light or a voltmeter or multimeter, test for 12 vdc on terminal 30. If you have power on terminal 30, then Fuse #17 is OK. (It should be, because the same fuse feeds the Defrost Relay, which does run the blower.)
- Turn the ignition switch on, and move the lower HVAC lever to anything except the left end or Defrost. Check for 12 vdc on Terminal 86. If you have no power here, the problem is in the wire between Terminal 86 and the control head. You must have 12 vdc on Terminal 86 for the blower to run.
- If you have 12 vdc on Terminal 30 and on Terminal 86, then temporarily connect Terminal 30 to Terminal 87. The blower should run. If it does not run with Terminal 30 connected to Terminal 87, the problem is between Terminal 87 and the blower motor.

Let us know in precise detail what you find.

WallyP

There is one possible reason that replacing the interior temp sensor could make the blower work...

The interior temp sensor fan motor is powered from the same connection that powers the blower relay operating coil. If the sensor fan motor were seized or shorted, it could drop the voltage low enough to keep the blower relay from operating.

Brett928S2

Hi Wally

That would make sense, as I remember trying to spin the tiny fan blades and they didnt want to spin easily....they were very stiff...


All the best Brett

Tony H.

Roger, I do not remeber you telling me anythng that needed to be rewired for the resister pack you sent me, is there some modification to the wiring that is needed to be done t make the new resister pck work? You did tell how to change the pack but I do not recall any wiring changes that needed to be made, if ther is what are they maybe that is why the resister pack did not solve my problem? I only took out the old pack and instaleed the new one unpluged the old unit installed the new unit then pluged it back in the plug there were no changes I recll you telling me to do to the wires or the pluf. IS there something I need to do to the new pack in wiring? this may be my whole issue. but i am going to try the smoke thing to se if my inside sensor is sucking in the smoke Mason has oferd the send me another one if mine is not sucking up the smoke as mentioned from Bret and Kevin. Roger let me know if there are wiring changes that need to be done and how they need to be done? Thanks.

Tony H.

Alan I have changed and swapped every relay that I can Mason has supplied me with others to try as well I used the horne relay and no changee either also the plug on the head unit is on tight and i have taken it off and on many times the only thing I see is thAT THE FLAT PLUG COVER TO HOLD THE WIRES IN THE PLUG WILLNOT LOCK TIGHTLY BUT ALL OF THE PLUGS GO ON THE HEAD SNIGGLY AND STAY IN PLACE.I got the new resister pack from Roger at 928rus and I do not recall having to chage any typ of wiring configuration it was just take out the old resister put in the new one and plug the plug into the new pack no wiring chages were made by me anyway. if I need to chage something in the wiiring please let me know what and how? Thanks.

the flyin' scotsman

The resistor group did change for the '89 MY as did the circuitry:

Tony H.

Wally P. when i am checking this relay is the relay inplave or is it not in the socket and i am checking the wires they feed at the head or just check the hole where the relay would plug in at. I can identfy the numbers on the relay they are number for you but will the holes do what they should do even if the relay is removed from it's position, i am very chalenged with electrical issues. I think I understand what you are saying but if the problem shows up between say 86 and the control head how do i know what wire is 86 on the control head or what block of wires would the 86 wire be in or let say it was 87 where would i locate that wire in the blocks and so on? Please don't think I am stupid but I do jewelry repair not electric and can turn a wrench and have a volt meter but if I do not what wire is 86 or 87 then i do not know where to trace it to. when i test for volts in the relay holes should i be using a metal ground or be using 85 Mp as the ground for checking other slots in the relay spot? Thaks for tolerating my stupidity in this but I will learn.

robot808

Tony,
Those numbers (30,86,87) are on the relays. Pull a relay and take a look it closely, some have a little diagram, others just have the numbers very small next to the posts on the relay. If you are not sure how a relay works, you might try wikipedia or howthingswork. Just get the basics of what you are dealing with and the stuff Wally and Alan tell you will make a lot more sense.
Also, ownership will be a lot more fun if you learn to read wiring diagrams. I went to my local library and got a book on basic car electronics, just a generic one. It started me out on simple circuits and worked up to more advanced. I am still a novice, but I usually understand what the experts here are saying now.
BTW, between Alan and Wally you have some of the best help on the planet right now.

the flyin' scotsman

Tony.........don't despair.

If you re-read Wallys post he describes to remove the relay and check the numbered points on the relay board. If the board isn't numbered reference the numbers on the relay as its fitted to the board and follow Wallys direction.

Alan

OK so if you replaced an '86 resistor pack with an '89-'93 version it will not work correctly without modification. Since the <'89 version seem to be NLA I assume this is what happened?

The pinout and function is different. The function can still be compatible with some slight modifications:

'86 Resistor Pack Configuration (Pin# / Wire Color / Function)
1 WT Blower Switch I-IV (SW1)
2 NA Same as Pin 6 (not used)
4 RE Feed from Blower relay
5 WT/GN Blower Switch II-IV (SW2)
6 BK Blower Motor Switch IV (SW4)
7 WT/BL Blower Switch III-IV (SW3)
8 RE/WT Thermal bypass - linked to Pin 4

'89 Resistor Pack Configuration (Pin# / Wire Color / Function)
1 WT Blower Switch I-IV (SW1)
2 NA Same as Pin 6 (not used)
4 RE Feed from Blower relay
5 WT/GN Blower Switch II-IV (SW2)
6 NA (not used)
7 WT/BL Blower Switch III-IV (SW3)
8 BK Blower Motor Switch IV (SW4)

So bottom line:

On the connector for the resistor pack cut/remove the RE/WT link between pins 4 & 8

Swap the terminal pin connected to the 2 black wires in pin 6 of the connector over to pin 8 of the connector - leave pin 6 disconnected. The terminal pins can be moved in the connector without soldering...

Alan