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Discussion Starter · #1 ·
Dear community.
My 1978 SS II has no heating or air con.
I wanted to start now with checking the power at the main ACU.
I can get the vent to go on all levels but I do not hear any servos or flaps moving when I turn the upper or lower wheels.
I thought the first step is to take off the center console.
I have loosesnd the bottom screws left and right but can't get it out. I don't see the two top screws I read about in an earlier thread.
Can you please help me before I break something?
Maybe also ideas on how to check the power.. Can this even be done in the garage with a switched off car?
Thnx
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Pull off the connector for the 44° sensor on the thermostat housing. Do a search for "44° sensor" on this site as it has been discussed several times in the past. This is the most common fault on the Shadow heating system, 99% it will be the problem. The 44° sensor prevents power getting to the system until the engine has warmed up to that temperature. To test you simply unplug the sensor and leave the wires loose.

And in my moderator voice, please take a moment to read through "Instructions for navigating the site" and "How to reply to a discussion thread"in the FAQ section, link here:FAQ There are other topics there that you may find informative. Please note also that it is not necessary to quote a previous post in your reply if you are following the train of thought in the thread, it just clutters up the thread unnecessarily. Thanks, Jim.
 

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You don't go in from the top, go in from the bottom on either side. You do not need to remove the console. If you follow the workshop manual there are procedures for testing the voltages on the ACU wiring connector plugs but if the ACU fuse is good then the fault will most likely be with the 44° sensor.
 

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Discussion Starter · #8 ·
To make things clear: I still need the engine to run to test the servos moving?
I unplugged the oil pressure switch (at least the one that stops the pump) is there another one?
And the 44 sensor. When I turn ignition to run neither fans nor servos move.
My fans were never a problem with the car running..
 

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Discussion Starter · #9 ·
Follow up for more input please :
I checked the ACU fuse at the firewall under the bonnet. It looks like someone has changed the setting to this modern 30amp version..? Next to it their is a loose connection. Any ideas?
I ran the car and let it reach standard temp.
The Fans work as always. Low and high. Auto in between.. But I don't hear any servos moving flpas when I turn the wheels...
I have the oil pressure switch off. And too of the 44 degree sensor which I guess is the one right below the thermostat..
So to make sure.. Do I need the thermal fuse at the compressor to be working? I'm not sure about this as the ac is empty and I had unplugged the fuse anyway for security..
Replugging didn't change anything..

Next step is, I need to find a way to. Look under the carpet for the mass? Correct?
I loosened the right an left screw on the middle concoles bottom. But can't get it out. It's stuck on top.. So I don't see the actual servo unit..
Help is appreciated.. I read all the chapters but I think I am missing something Vasco before it gets to calibration
 

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Engine does not have to be running to test anything, but ignition must be switched on, but when doing so remove the oil pressure switch wire and also the coil positive wire otherwise the ignition module can be damaged. On the 44° sensor, it is the one with two wires in a plug on it. Pull off all the two wire plugs on the thermostat housing to be sure it is disabled for testing. The other plug will be a fan thermostatic switch. The 44° sensor moved around on the thermostat housing depending on year, if you search "44° sensor" or "44° switch" on this forum you should find several posts with images of the various positions and the correct one for your model. The shortcut is to just unplug all two wire plugs from the thermostat housing for testing. AC compressor fuse does not have to be connected for heat to work.
Again, you do not need to remove the centre console to get at the ACU servo assembly. Remove the vertical trim carpet between the transmission hump and the console and the ACU servo unit will be visible. The servo modules that control the servos and actuators are on either side of the unit and plug in. Each of those modules has two relays on it. The module pins often get corroded so pull those off and clean them first. Then go to TSD 4200, section C7 which will have a diagnostic fault chart for each part of the system to identify what part is faulty.
 

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Discussion Starter · #12 ·
Thank you Jim for the time taken to clarify!.. I unpluged both 2 wire plugs.. I have the oil presure disconnected.. but not even the fans turn on like this!.. there must be another blockage ?..
when I start the engine the fans work.. but no flap or servo..
 

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Discussion Starter · #13 ·
Aamzing. thank you for the pictures, too... yes.. as you can see above .. unfortunately I dont have these screws!.. I am planning on putting a bluetooth unit to the radio so I need to take it off later.. but first of all.. the heater needs to work *
 

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Discussion Starter · #15 ·
Hi Jim. So I got rid of the carpet and the Servo unit actually looks pristine.. Not sure if that is good or bad. Lol. Still nothing works. I cannot make any tests from c7 as no Servo moves at all. I must miss something! I unplugged the oil pressure and both 2 wire thermostat switches. But with ignition on neither fans nor servos move when switching to low or anything.. And moving the wheels. When the car is running only the fans work. Somewhere the power must be cut.
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Suggestion. When you see ground hubs as we see here, clean them with a wire brush and smear a protective grease layer to prevent oxidation.
 

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OK, so at "A" in the image below, the bent cable shows that your water valve is seized and the servo arm has bent the inner Bowden cable into a "U". The cable itself may also be seized, disconnect at the water valve on the inner fender on the left hand side of the engine compartment and try to pull the cable from that end. If it is stuck apply a 50/50 mix of acetone and ATF along the cable outer sheath and allow to soak in. That should free up the cable. Try working the water valve manually by moving the lever on the valve in the engine compartment until it moves freely, then reattach the inner cable once it also moves easily. At "B", that module circuit board with the two relays on it will pull straight off, there is an identical one on the other side. Pull them both off and make sure the contact pins are clean and remove any visible corrosion. These relays operate the servo motors, temperature up on one, down on the other on each module. One side is for the upper temperature wheel, the other is the lower one.. After cleaning those pins, I think you need to check voltage and / or operation of the inhibit relays and the voltage stabilizer, see section C5 for procedures. That square black Bosch relay beside the 30 amp fuse in your image above is not original, it would have been a Lucas 6RA so someone has obviously had an issue there and replaced it. Make sure that relay is working, even jumper it for testing as it could be the source of the malfunction.

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Discussion Starter · #18 ·
Amazing work. Thanks Jim. I'm. Not sure I can reach the bowden cable underneath the valve.. It's so tight with the break fluid reservoir. I already bought the whole heater valve as replacement as I was sure it was stuck and it's leaking a bit. Will try to replace it but still waiting for my ba2 wrench to show up
 

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Use an 11/32 wrench in place of a 2BA, works fine. Bosch relay is OK, works as well as the original 6RA. That relay is the AC fan and compressor relay, and the loose brown/blue wire should be connected to it. See TSD 4200, chapter C, C4-1 which describes the Interlock and inhibit systems and that relay. Someone has replaced the original Lucas 6RA relay with the Bosch one, which will work OK but I suspect they have not wired it correctly as evidenced by the loose brown/blue wires. Have a look at the Lucas 6RA terminal schematic and cross it over to the Bosch and make sure the wires are in the right place on the relay.
 
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