My fix for the 348 Climate Control Problem. With Pictures

I bought a 95 348 spider a few months back with inoperative climate control. I fixed the hidden fuse, cleaned the contacts at the main panel connector, disassembled the controller and cleaned internal contacts, and repaired cut wires near the controller. I finally got my controller to light up, then came the error codes. I had e5, e6 and e8. There are 3 small reversible motors that perform various functions, as directed by the controller. I found that all 3 of mine were seized. I was able to unstick all 3, but in the process wrecked the gears on the flap door motor. So I adapted a motor from a Volvo. I could never clear code e5. In the process, I found that the Bosch motor that controls the heat valve was used on some SAAB 9000's. I couldn't find one at the JY or online. I disassembled it multiple times, measured the resistance of the variable resistor, checked to see that the signal was getting through to the controller. After about 15 hours of this I gave up and designed my own system. I removed my factory controller and made a panel that fits over it. I got a fan switch from a BMW and a resistor pack from a Crown Victoria, which I was able to fit in the AC box where the old variable resistor went. I got new connectors for my motors, and unplugged the old ones, leaving the factory wiring in tact and in place. I used reversing linear actuating switches for these 3 motors, another on/off switch for the auxiliary heat pump and another switch to shut off the fan all the way. I bought a digital 12V DC thermostat from an ebay seller for about $15. I wired in a relay for the whole system. I wired up the whole thing and installed it. I have tried the 3 reversible motors and they all 3 work. I have not yet tried cycling the AC compressor with the thermostat, as I have to recharge my system after the engine out/replacing the compressor. I hope the pictures are somewhat self explanatory.
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Has anyone tried to modify a 355 control panel into a 348

 

Good work!

 

Dang!! That's impressive! You must have a degree in electrical engineering. Sure makes my slider controls look prehistoric. (although they work quite well). I'm sure you've spent hours going over the electrical schematic for the climate system, so you know this already, but just in case, don't forget for the A/C you will need a signal to the compressor clutch, but also to the fan for the condenser in front of the right front wheel. There's a relay for each up in the "hidden valley"..

 

Outstanding job!!!

You get a Stoogewerks award!

 

I see a fledgling business (cottage industry) in the works!

Can you price one out (plug and play) so I can have it available when mine goes kaput?

Maybe some slim rockers as an option?
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Haha while working on this I was thinking of you, pnicholasen. I got pretty deep into diagnosing the stock system, and deduced that I had reached the limit of readily available (google-able) knowledge on the system.

Using that digital thermostat I am running a ground through the original wire, with one of those clip into the wire style connectors, coming from the control panel to wherever it goes. I read the diagram a few days ago and don't remember the destination, but I believe it goes to the relay that runs the compressor and also the one for the fan. This was one concession I made to not altering the stock wiring harness. I haven't tried that part yet but I assume it should turn on the fan as well.

 

Thanks. I would consider doing that. I guess I should wait until I have charged the AC and tested the whole thing. I haven't hooked up the LEDs yet. Not sure if I'll need them. I don't think I need the one for the drum motor. Just run the switch until the air comes out where you want it.

I think it would be neat to have the panel engraved with labels for the various functions. I might do that.

Those slim rockers look nice. They would work for the two switches on the left but probably not for the other 3. You need reversible polarity switches. They have 4 connectors, 2 for +/- in and 2 to the motor.

I accidentally purchased non momentary for those. I need to order some momentariness. I run the risk of burning up the motors with the ones I have now.

 

I managed to build a "stand alone" AC control circuitry in the existing AC controls box. My AC control box was completely dead (disconnected) when I bought the car. I tried to "revive" it but found that one of the large chips inside was getting very hot so it was out of the question.

I started with the idea to just install a digital clock inside the empty box. Then, why not add a thermometer, reinstate the blower fan speed control and the bar indicator (digital potentiometer)...

...and then I went on reinstating all controls building independent control circuits using relays, flip-flop electronic switches etc. Took months but now I have all controls using the original box and buttons.

What made the work easier is the fact that I don't use the heater system (I have disabled it as I don't need it in Malaysia). To control the flaps with the new system, I had to attach micro-switches to the fresh air and air distribution motors to limit their open-closed positions.
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WOW!!!

That looks like a bunch of work, but I'm sure you are very happy with the function of it now. Thanks for sharing.

 

Now that is really incredible! Nice work.

 

OMG! That is so over the top. I wouldn't even know where or how to start on a project like that. Simply amazing and very nice work.

 

Great work.

My unit stopped working and I found someone who fixed it.

https://www.ferrarichat.com/forum/united-kingdom/440404-348-c-control-unit-repair.html#post142986206

 

m.stojanovic....with your first post you blew me away....and i also read you're local! (that's the first time i have ever said that on this board in almost 3 years!)
now, i need to get in touch with you!!!
pm sent!

 

And here I am playing with microcontrollers, and you go old school TTL. Awesome job. You deserve the official, honorary title "ElectroStooge."

 

If your AC control box has failed and you are modifying the system, one part that can easily be reinstated is the Variable Blower Fan Speed Control (provided the controller is still good). The controller, pictured below, is located at the left side (LHS of the car) of the heater/evaporator box, easily accessible from the boot/trunk. The wires to the two connectors: 1-cut leaving a length; 2-keep; 3-keep; 4-cut (not used); 5-cut (not used); 6-cut leaving a length. The wires 1 and 6 should then be connected as shown on the diagram. In this way, you avoid adding fan resistors and, instead of the bulky fan switch with a number of speeds, you have only a potentiometer which will continuously vary the blower speed from zero to maximum. A more sophisticated solution is to use a digital potentiometer (easily built using small chip) instead of the mechanical one. The existing button switches on the AC box (up and down arrows) can then be used to drive the digital pot and control the blower fan.
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I am reviving this for my problem. I can use Car Whisperer help

I have the blasted E5 error, heater on all the time, fan on high. All I need to do is to have the AC on all the time, control it with the fan, and by pass the heater.

1. I will remove the heater hose from the pipe feeding it to the heater valve, and feed the hose back to the engine, bypassing the heater valve all together.

2. What do I need to do to make sure the AC is on all the time?

3. How do I still control the fan speed from inside the car

 

Subbing to this as I think will be a very helpful thread

 

For the fan, check the entry right above your question. As far as having the A/C on all the time, that would technically be easy to do, but ( and this could be totally wrong) I think you can't have the compressor running constantly or you could freeze up the evaporator. Compressors cycle on and off instead based on a temp probe in the evaporator sending info to the thermostat which, based on how cold you have it set for, determines how often the compressor kicks in. As far as hooking up a thermostat, he talks of a digital one, which would be great if you know how to hook it up. If you check my yawn inducing video series "Ferrari 348 Climate Control Substitute" you'll see I went very old school with ancient analog technology thermostat that even I could understand, but it works fine

 

When I bought my 348, it already had a modified AC system and the (dead) AC ECU was completely disconnected. A capillary thermostat was added (as on the pic) as well as resistors and a multi position switch (1,2,3,4) to control the blower fan speed.
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The AC system is actually "always on" as it gets ignition switched power which goes to the two relays next to the main 30 Amp AC fuse.

One relay is for the blower system (always on with ignition) and it provides power to the Fan Speed Control Unit shown in my previous post. Even though the blower system is powered up with ignition, the fan will not turn until it gets a signal on the Pin 6 of the Fan Speed Control Unit. This signal is normally provided by the AC ECU and it is a positive voltage varied from 0 to 5V. What I initially did was (after removing the added fan speed resistors), I cut the wire going to Pin 6 of the Fan Speed Controller and connected to it a standard 50 Kohm potentiometer which gets +5V supply from a voltage stabiliser (LM7805, see diagram on my earlier post) so that I could manually vary the voltage on Pin 6 from 0 to 5V. The fan worked fine, I could control its speed like the volume on an amplifier. You can ignore the red line on my diagram going from the connection between Pin 1 of the Controller and LM7805 to the "Ign Switched +12V", just tap into the Pin 1 wire and connect it to LM7805.

The other relay is for the compressor clutch. The relay coil gets +12V (on relay pin 86) from the ignition and its ground side is switched on and off by the AC ECU. So, to switch the compressor clutch relay on and off by the capillary thermostat, you need to cut the "VN" (green/black) wire going to the clutch relay pin 85 and connect it to the thermostat switch. The other thermostat switch terminal should be connected to the ground.

 

Mitchell,

Do not feed the the hose disconnected from the heater valve back to the engine, just plug both, incoming and return, heater hoses. I disconnected them at the engine side and plugged the heater hoses there.

If you feed the heater hot water supply back to the engine, this flow will not go through the radiators (will not be cooled) and may cause overheating. Plugging both heater system hoses will force the whole water pump flow to go through the radiators. There is no danger in doing this, it will be exactly the same as when the heater valve is closed (when the heating is off).

 

To run the AC compressor you need some sort of a thermostat too cycle it. You could run the type of digital one I used. Less than $20. But you have to mount it somewhere. That one stojanovic did is awesome! Way, way better than my hack job. Then again, mine is simpler and it does work

 

Thanks for all the suggestions. This is what I am going to do for now to get going.

1. Plug up the coolant passages to the heater core
2. Wire in the 5V regulator and a 50kohm pot as a fan controller switch
3. Wire in a simple switch to ground to control the compressor clutch.

I will modulate the compressor manually, as needed for the time being until I can find a thermostat. I just need to get this thing running so I can even charge it up.

Any pointer to a thermostat is appreciated.