A.c. Compressor wireing a little help please

[aluminum]

1980 U.S. 928 Air Con. Issues .
Air Con Compressor Hot Lead Wire Go's where ?
Mine is Broken off and I cant find where to hook it to

I See 3 Wires on top of the AC. Compressor . 2 go into the Compressor and 1 comes out and looks to be the " Hot Hook Up " when engaged Red in Color
It is clipped or broken off about 6 inches from the Pump and I see no wire hanging to Hook it to
Where should the wire hook up to ?
If anyone has a 1980 or 81 and could look under their Hood and look for the Hook up
a Photo would be a Big Help
( Compressor runs fine when I hook a hot lead to it )

[JhwShark]

Try Roger for the cd manuals. A red lead (2.5mm) goes from the Cooling motor directly to the control panel plug Q3 then to pin 87 of the cooling fan relay (XVIII). The fuse (#16) goes to pin 30 of the same relay providing the voltage to pin 87 when switch is on.

There a few dependent devices that are in the circuit...you need the current flow diagrams...

This info is for a '79, but should apply to you.

[aluminum]

Originally Posted by JhwShark

Try Roger for the cd manuals. A red lead (2.5mm) goes from the Cooling motor directly to the control panel plug Q3 then to pin 87 of the cooling fan relay (XVIII). The fuse (#16) goes to pin 30 of the same relay providing the voltage to pin 87 when switch is on.

There a few dependent devices that are in the circuit...you need the current flow diagrams...

This info is for a '79, but should apply to you.

1979 is Different Says the Chart Say's 1978 to 1979 ( Rodgers chart )
78 & 79 has a AC Compressor Relay in Socket 16
" my 1980 has no Relay in Socket 16 and looks like it never had one " However I Bet wires run to the back of the socket
do you suggest I put a relay in socket 16 ? as if the Car was a 78 or 79 Yr Model .
Chart also says 1978 to 1981 : AC FAN RELAY Socket 9
You Mention " cooling fan relay (XVIII) " Well XV!!! ( 18 ) is my Washer Relay so that makes no sense to me or I am misunderstanding you totally
Your saying that the :
" AC CONDENSER FAN FUSE " # 16 on Panel is the Fuse for the AC Compressor then
Interesting ? they left out the word Compressor strange .
About this " A red lead (2.5mm) goes from the Cooling motor directly to the control panel plug Q3 "
I Don't know ( Forgive me ) what you mean by " Plug Q3 ? certainly you don't mean Socket 3 the window relay .
About the Cooling Motor by that do you mean the electric Fan in front of the Condenser ? or the Blower Fan
Sorry I am having trouble Understanding your Help But Thanks Much
I Can Download the Wiring Diagram next time I am on Hi Speed .
I See on a site that the AC Hot Wire should run in Front of the Right side Cam Cover But I don't see one .

[JhwShark]

My reference is the Porsche 1979 Current flow diagrams. I am using the words off of the diagrams and indicated that I am referring to a '79 which of course is a CIS maybe your MY is not CIS.

If you have the charts then just make sure you are wired up appropriately for you MY.

The reference to Plug Q3 is to the row of plugs with wires at the bottom of the Central electric panel (CEP)/fuse panel. The plugs go from left to right a-z (or so) usually the plugs have the Letter in black ink (handwritten) on them...I suppose you have not gotten into looking at the CEP in great detail yet...most everything electric will go through here to somewhere, though some do not.

[aluminum]

Anybody have any idea where the Hot Wire for the AC Compressor should be found so I can hook it up to the Compressor ?
Example : wire should be coming from wiring loom top of motor next to Fuel Line near Passenger side Cam Cover
Example : Wire should hook up to 14 Pin connector Number ?
1980 US Model is the Year
I Hate to run a wire from a switch under the dash to the Compressor to turn on the Pump .
Surly someone must Know where this wire should be found .
Thanks if anyone knows
At this point I shall check out the AC Fan Relay in Socket # 9 as that's the only Relay Listed on the Chart related to the AC at all.
How some other year works well not help me set up the 1980 US Model unless Its exactly the same .

[aluminum]

Originally Posted by JhwShark

Try Roger for the cd manuals. A red lead (2.5mm) goes from the Cooling motor directly to the control panel plug Q3 then to pin 87 of the cooling fan relay (XVIII). The fuse (#16) goes to pin 30 of the same relay providing the voltage to pin 87 when switch is on.

There a few dependent devices that are in the circuit...you need the current flow diagrams...

This info is for a '79, but should apply to you.

Well Thanks " JhwShark " to You I made Headway today I decided by Cooling Motor You Must Mean the AC Compressor. ( Not the Cooling Fan in front of the Condenser )
So I Removed My Fan Cooling Relay ( # 9 Socket in this 1980 )
and also the Q Plug at the Bottom of the Wiring Panel
I Jumped the 87 Pin and the 30 Pin of Socket 9 and nothing happened Key on or off
Then Leaving the Jumper I replaced the "Q" Plug and the Condenser Cooling Fan started running . Yea .
Then I Checked the Conductivity From " Q 3 " ( Left side of Q Plug ) to the Cooling Fan Relay and found " Conductivity so I knew I was on the right track THANKS
Then I Checked for Power at Q3 and discovered that with the AC Button Depressed ( engaged ) I had 9 / 10 Volts at Q3 motor off
Motor Running I had about 12.50 Volts
So Now I am on the right track !!!
I wish I knew where I should Look for the Q3 Wire under the Hood Like some wiring Loom or whatever . I Looked all around but see No Loose wires Hanging.
So Unless I go to a Porsche Salvage and see a 80 or 81 Model still Intact I can Look for the wire .
Looks Like However since I am Far up in N Cal I well have to do this as a fix for now .
Run a Wire from the Back Side of Q3 to the Compressor so that when I Press the AC Button the Compressor well Run.
Now I Expect this direct Wiring well mess up all the signals from what you call
the ' dependent devices '
"Quote "
" There a few dependent devices that are in the circuit...you need the current flow diagrams... "
...
I Expect the Cooling Fan in front of the Condenser well not come on until Device
perhaps Temperature controlled tells it to
I have read how some Wire the Cooling Fan to run at any time the AC is on
Perhaps I should do this ? Not sure about that
Any further Suggestions Much Appreciated
By The Way I am familiar with the Electric Panel Board and have worked with it front and Back But never really Dealt with the " Plugs on the bottom before "
Much Regards

[Fredfox]

Im not familiar with earlier models but,
There should be a switch on the drier that is most likely mounted in front of the radiator.
After it leaves the cab, goes to the thermal switch then the drier low pressure switch, this wire would go to the ac compressor.
Of course I could be wrong.

[JhwShark]

There are a few harness/looms that go from the CEP forward into the engine room. I would think, based upon the Cooling motors location, that it would come forward to where you see under the Hot/Jump post the end of harness (or combined/merged looms) that supplies the three 4mm Red leads to that post. I believe the wire you are looking for would be in these bundles that run along the upper passenger side engine room from the post back to the CEP.

I do not believe it would be at the 14 pin for any MY. My diagram shows a direct connection from Q3 to the device, I believe all 928's would be hot directly to the motor...the dog's gotta hunt...logically it should be near the device and close by harnesses. Any low voltage induction trace you can do isolating the wire off Q3 would be nice.

[Danglerb]

Pretty sure all have the protection of high temp and pressure switches between power and the compressor clutch.

[aluminum]

Low Pressure Dryer Switch ( Near or next to the Dryer front of Radiator Area

Link to this Info :
THE 928 HVAC SYSTEM
starting with the 1980 year type , and yes there were two versions , version one= Non Climate Control( can be recognized by NO temp sensor vent in center console(upper section) . Version two= Climate control (has the temp sensor )one inside as mentioned and one positioned outside in the left front guard area. Also for the 1980 to 1989 is the large and highly respected N/D A/C compressor , and from 1980 to 1986 a much larger A/C condenser electric fan , the non climate control version was deleted around the time the 4.5 928 was discontinued .

As is often the case with a 928, the most common problem with the electric cooling fan seems to be bad connections on the fuse or a bad relay. The fan motor, coolant temperature switch, refrigerant temperature switch, and wire harness can all fail, but these failures are much less common than fuse and relay problems.
************************************************** ********************************************
Another problem with the electric cooling fan is that the refrigerant temperature switch seems to be ineffective. It would be better if the electric fan ran any time that the A/C compressor was operating. One way to accomplish this would be to install a heavy-duty in-line relay, triggered by the A/C compressor signal, to operate both the compressor clutch and the cooling fan. A diode should be used at the fan, to prevent triggering the compressor when the temperature switches operate the fan.
************************************************
The electric cooling fan may not run as often as you expect. On cars up thru ‘86, the fan does not automatically run when you turn the A/C on. It only runs when the coolant is very hot or when the Refrigerant temperature switch is triggered.

To check the electric cooling fan, turn the ignition switch on, pull the connector from the refrigerant temperature switch (located on the stem sticking up from the receiver/dryer between the radiator and the bumper), and jumper between the contacts in the wire harness. The fan should run.

If the fan does not run, replace the connector, and pull the cooling fan relay (not the blower relay). Jumper between terminal 30 and 87 in the relay socket - the fan should run. If not, check for 12 vdc at the fan motor connector. If there is 12 vdc at the fan connector and the ground is good, but the motor does not run, the fan motor is probably bad.
Note from Aluminum :
I am Not sure where the location of the evaporator temperature sensor is but under the dash I think on the Drivers side

[aluminum]

So First Step at this Point well be to test for Current at the Low Pressure Dryer Switch
Also to Test for Connectivity to see it that's indeed the correct wire coming from Q3 to the This Dryer Switch .
At This Point if I Have Current at this Switch when the AC Button is engaged I should be able
to Power the Compressor from this switch
Since I Can't find the Wire to Hook to the Compressor coming from the Switch Yet I May have to Run a wire from the same ( Low Pressure Dryer ) Switch.
However now that I Know of this switch Perhaps I can trace down the wire Finally . My Guess is that it is Broken off just inside of some Wire Loom very Near the Hot Post of the 14 Pin Connector > Pass side Front next to Cam Cover on Fender well
Another BIG Issue is the Type of Oil in the Compressor .
Since the Car sat for some 15 Years certainly the " Type " of Oil in the Compressor most likely is not compatible with the Current types of Refrigerant .
IE: the Mineral Oil well not work and upon running the Compressor with the Old Non compatible Oil the Compressor well be Toast in short order .
Toast anyone ?

[Alan in AZ]

Yes you are now on the right track. Lets stop calling an AC Compressor a Cooling Motor - someone is not helping here - I think they were answering a quite different question on the cooling fan? (nothing on your 928 is called a 'cooling motor' you have a Compressor & a Cooling fan which are of course very different things).

Power to your AC head unit also supplies the AC Compressor Clutch - This power is supplied via Fuse #9. Power enters the AC head unit on its pins 4R & 5R.

A switch in the head unit slider connects power to the evaporator freeze switch (located in the bulkhead area under the cowl - on the Air plenum). The slider switch output exits the AC Head unit on its pin 9L as a Violet/Yellow wire and travels through a single pin connector to the Freeze switch. (need 12V+ on both switch pins for AC active).

From the Freeze switch it is connected (another Violet/Yellow wire) to the Central Electric (fuse/relay) panel on pin J2 (on bottom connectors) from there is just connects to pin Q2 (no other internal connections) and exits as a Black wire (in a loom) to the low pressure switch mounted near the AC dryer. This loom goes through the firewall grommet and runs under the (LHD) passenger fender lip to the front.

From the low pressure switch (open when refrigerant pressure is too low) a black wire goes back to the 14 pin connector (also via the loom) on Pin 9 and carries on as black wire (now in the engine loom) to a single pin connector where it splits to two black wires; one to the Compressor Clutch and one to the Supplementary Air valve (for AC active idle compensation). The final leg to the compressor should have another single pin connector where it switches to a red wire (the final leg to the Supplementary air valve stays a black wire). These two single pin connectors should be near the loom & near the AC compressor...they may have been ripped off... if so you can run a new line direct from the 14 pin connector to the AC compressor clutch(its quite close) - however you must also find & connect up the supplementary air valve or you may stall at idle with the AC on - you can find that later of course...

Central Electric Pin Q3 on your car is not related to the AC clutch - only the Cooling fan. You do need this to operate correctly for AC (and engine cooling), but its quite independent. If your cooling fan works normally in driving - then don't worry about it for now - until you get the AC compressor working.

Alan

[aluminum]

About the Compressor Oil after Wiring the Compressor to Run

[JhwShark]

Alan is the expert in our electronics.

My apologies for referencing Cooloing Motor...this device is stated/named in the 1979 Porsche 928 current flow diagram as are all the dependent devices. Of course not having a dictionary to translate the terms within the diagram can cause confusion.

I have said you need your MY diagrams, for true reference info which can then be used to determine what is still original and not.

Aluminum...nice detailed info pasted in...where does it originate?

[aluminum]

Thanks Everyone for the help :
The Bits and Pieces I Got that Turned into Detailed Help of the right sort has Helped Me enough to Know how to search the net and get additional Help.
However Now It's all right here from You Great Members .
Your all Smart and Professional and very friendly
PHOTO OF supplementary air valve ( From the net not my Car )

Today I Used Your Help and Jumped the Low Pressure Dryer Switch after checking that it
(1) Indeed Had Power with the Key on and the AC Switch Engaged
(2) Switch was Closed and i jumped it
(3) This Allowed me to Check for Power at the supplementary air valve
3A was no Power until I Jumped the Low pressure Dryer Switch
(4) Upon Realizing that the Power for the AC Compressor Must Come from this same switch since I had no wire going to the AC Compressor I Soldered in a new Lead
with 2 Wires . 1 to the Compressor and 1 to the supplementary air valve
.......
At the AC Compressor was 3 wires 2 going in to it and 1 coming out RED in color that changed to Black after going through a Factory wiring Junction ** However this wire ended after about 5 Inches Cut or Broken off .
TESTING :
Simple Start the Car and Engage the AC Button
RESULT : AC Compressor now spins and stops when AC Button is disengaged
So The Basic Function is working now
Of Course I expect the Refrigerant is low after 15 years of non use humm
I Hope I can find some Compatible Refrigerant with the Oil in the Compressor so I don;t mess that up.
ABOUT the supplementary air valve in case someone was wondering that's a Valve to speed up the Idle when the AC is on

[Danglerb]

Evacuate, leak check, purge, replace dryer, hold a hard vacuum for a few hours, refill. R12 if you can get it works best.

[aluminum]

Originally Posted by Danglerb

Evacuate, leak check, purge, replace dryer, hold a hard vacuum for a few hours, refill. R12 if you can get it works best.

Thanks I doubt I can get R12 ?
ABOUT THE DRYER
Just what Exactly goes wrong with the Dryer anyway ? I can find no info on the net so far on that > Just says replace it < But not why ? or what goes wrong with it
Does it get Plugged up with something ?
I understand you can get a aftermarket one for much less other then the original one . Also that they work just fine .
Here are some comments from Pelican :
Comments: I am having question about the a/c of porsche cayenne.when do we need to replaced the dryer cartridge and what is the symptom or reason to replaced it.
March 15, 2012
Followup from the Pelican Staff: If there is a leak in the system or a restriction, you would replace it. - Nick at Pelican Parts
Comments: I have a 1985 911 cabriolet. I took the belt off the compressor 10+ years ago because the a/c never cooled very well and i got tired of replacing Freon. Will there be a problem if I put a belt on and recharge the system at this late date?
August 8, 2011
Followup from the Pelican Staff: Maybe. i would check if the compressor spins freely. Sometimes compressors will seize when not used. At the minimum, check it for leaks and replace the receiver/dryer. - Nick at Pelican Parts
Comments: I have an 87 944S, and would like to get some A/C going for the hot summer, but the system only takes R12 and that is not available in stores... rumors have it that some places may sell it but will charge an arm and a leg due to the environmental controls. Anyhow, I have seen the R134a conversion kit which adds some sort of valve. Is this something I could use and do myself? You mentioned earlier that 'extensive' changes are required, but I wonder if I can get more detail. Also, I don't know how long it has been not working, so could other things be wrong with it clutch?. The fan blower works, heat works great. Thanks!
June 17, 2011
Followup from the Pelican Staff: I would have the system leak checked. Repair the leaks. Then replace the receiver/dryer and retrofit to R134. You should be OK. - Nick at Pelican Parts

[aluminum]

Humm I stand Corrected You Can buy R12 I see lots of it on CL runs about $20 Per Can
That's good advice you gave me " Danglerb "
I like the idea of holding a vacuum the longer the better > what about 27 inches ? or so
************************************************** *********************
Whats evolved with changing the seals ? Must not be all that many seals are their Anyone ?

[Alan in AZ]

If the dryer has been exposed to an open system (e.g. leaking) then its been exposed to a lot of moisture (in ambient air)... this means it's already accumulated all the moisture it possibly can and is now exhausted... You need a new one - don't even think about it...

Alan

[aluminum]

Originally Posted by Alan in AZ

If the dryer has been exposed to an open system (e.g. leaking) then its been exposed to a lot of moisture (in ambient air)... this means it's already accumulated all the moisture it possibly can and is now exhausted... You need a new one - don't even think about it...

Alan

" Gotcha on the Dryer "
Thanks Alan For all the Expert Electrical Help / Advice
I Must Admit I was a Bit Surprised the first time Viewed the Electrical Panel
Fuses / Relays and all the Plugins / Upon Flipping the Panel over and seeing the Mass of wires twisting every which way I had to Laugh a bit .
Having owned a Ton of Cars this was a " Experience " to use a word .
once I get the Air up and running I do like the Idea of the Cooling Fan running all the Time the AC is on .
As I also have a house in Las Vegas where it is Very Hot a lot of the year. However I well give the Factory System the First Shot