Dead HVAC/AC panel

Did you actually test the hidden fuse, or just visually inspect it?

Mike

 

I'm back in town next week. I have a spare unit you can borrow for a test.
Bertil

 

You might try taking it apart to see if there are any bad solder joints. If it turns out to be truly dead I might be a buyer if it's not too expensive. I know others have gone down the path before, but I'm wondering if it's possible to create a circuit to replicate its function.

Best of luck in finding a fix. Fears about the CC unit were my biggest worry in finally deciding to buy a 348.

 

GOOD EVENING!
HOW'S YOUR FRIEND RESTORATION !?
PASSED PRA GIVE A TIP HOW TO REMOVE RUST!
THESE MINI grinding DO REAL MIRACLES!
EVERYBODY MUST HAVE ONE!
STEEL BRUSH IS THE MAXIMUM PRA THAT KIND REMOVAL!
HUG AND GOOD LUCK!
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GOOD MORNING!
HI
IT SEEMS REALLY UNDERSTAND THE SUBJECT!
MORE ATTEMPT TO CLEAN THE CONTACTS OF OXIDATIONS AND REVIEW THE WELD POINTS!
CAN ONLY BE EVIL CONTACT!
AT 348 is INCREDIBLE AS THERE ARE SEVERAL PARTS ARE EXACTLY THE SAME USED CARS SIMPLE WELL, YOU HAVE AN IDEA PRA when I needed CHANGE MY SENSORS OF THE TPS 348 costing U $ 300.00 AND JUST FINDING THAT WERE ABSOLUTELY THE SAME OF FIAT UNO IN US $: 30.00 !!!!!!!
IN MY CENTRAL PANEL THAT IS WHERE YOU ARE WORKING NOW, ONCE BURNED A CERTAIN OF THESE SMALL 4 RELAYS, AND THE SOLUTION WAS THE SAME AS NOW ISIC, SHAFT FIAT (LAUGHS!)
HUGS AND HAPPINESS!

 

That's not correct - A HVAC failure could just as easily be an internal component failure as a bad contact!

BMW's E36 are well known to suffer similar failures of their digital climate control units (BMW's version of HVAC/AC), and the cause of the fault is due to a failure of a capacitor on one of the circuit boards.

Replace the capacitor and the control unit is as good as new! (guess how I know this! )

Bad contacts do cause a lot of issues for the 348's HVAC/AC panel, but as far as I'm aware, it's never been proven to be the cause of dead HVAC panels.

 

voltmeter

 

Is your clock working?

 

I'm not trying to hijack this thread but it's funny you asking if the clock works.

My HVAC/AC was previously working okay (it would occasionally play up and cut out but a quick press of the fan speed button would get it going again), but the clock would never work properly (you could set the time and it would run okay but when you turned the car off and back on again the clock reset back to zero).

Since having My hazard warning light switch relays fixed (which required removal of the HVAC/AC panel), the AC/heater section of the panel no longer works but the clock now works perfectly and doesn't keep resetting itself!

(Annoyingly, the day I collected the car from the service the AC/heater worked perfectly for the whole day. The next morning, the only thing the panel did was tell you what the time was!)

The whole panel lights up and displays correctly with no error codes showing, and when you press the fan speed buttons the display alters correctly but the fan does nothing (I need to check the contacts for the HVAC plug and also investigate the fan speed control module by the looks of things).

Out of the blue the other day the AC/heater suddenly started working properly again, but later that same day it decided to quit again.

If it comes to having to choose between knowing what the time is and being kept warm/cool then I know which is more important to Me! - And I always wear a watch anyway!

 

When I purchased my 348, the climate control system was dead. I got a big discount on the asking price because of it. It turned out that the "hidden fuse" was partially melted in its holder. It didn't actually burn out the fuse, it would pass current along the system until it got hot, then break contact. I fixed the problem by installing a heavy duty, gold plated, cylindrical fuse and holder, with vastly more contact area for current flow (less heat). This is the kind used for big automotive stereo amplifiers. Still a 30amp fuse, but far less heat produced.

If the problem is here, it will disable the clock at the same time, IIRC.
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Congrats on selling your car Per! But I was hoping for an answer on this as I'm having the same problem.

Is there a way to power the unit when it's removed from the car? Just want to see if it lights up.

My hidden fuse is good. The unit worked fine a few months ago but now it's completely dead. I would like to narrow it down to the unit or a wiring issue.

Thanks

 

To power up the AC ECU:

Pin 1 (brown) - permanent +12V
Pin 2 (pink/black) - Ground
Pin 3 (green/white) - Ign. +12V
Pin 26 (white) - ECU illumination

I do not know offhand the positions of the listed pins in the ECU socket but you can determine if you find out where the mentioned wire colours connect to the connector block.

Otherwise, I have a cut-off male connector with a short length of all the wires going to it and I can let you know the pin positions over the weekend.

 

Thanks M
I think I understand that. I'll give it a try.
If you have the pin positions please let me know.

 

Here's the pinout of the AC ECU. You will have to make some tiny insulated female plugs with a length of wire in order to connect to the pins for testing (especially since the "+" and "-" 12V pins are very close to each other (Pins 1, 2 & 3) - don't cause a short circuit. You can determine the wire colours and the functions of the other pins by looking at the wiring diagram. I have verified the actual wire colours to the connector block with what is shown on the diagram - all checks OK.
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Thanks again Miroljub!

Cheer's