1996 854 SE 2.5, Multiple ECC issues (with fault codes)

[granite]

I recently bought an old 850. I knew that the ECC wasn't fully functional when I bought it. It always flashes the REC and AC orange lights at start-up. I'll give you a list of the symptoms, along with the fault codes I got out of it earlier today.

• There is no cold air from the AC. I can get cold outside air, but no active cooling. I have not yet attempted to investigate the cause further, since I wanted a full list of fault codes from the system first. According to the previous owner, the AC definitely worked three years ago, and definitely did not work last summer. So whatever went wrong happened somewhere in between. That said, though, I can't really test the AC properly when it's cold outside. It's only a few degrees above freezing here still. Or is there a dead-sure way to determine if it works, but poorly, or doesn't work at all? Even though it's cold outside?

• The fan works, and the fan speed can be adjusted, but very little air comes from the main vents on the panel. The ones out to the sides put out a bit more than the center ones. The left center one is like a puny baby fart, even when the fan is roaring at full speed. However, if I open the "Outside air" valve, the same vent provides a strong blast of cold, outside air. It's like the air duct for the internal air (hot or cold) doesn't open fully to the panel vents. The vent that runs along the windshield works fine, though. It blows hot air at full force with the fan on high.

Below is the full list of fault codes I got from the ECC. It looks to me like most of them, perhaps all, could be related to a single bad electrical connection somewhere. Either a connector or a ground cable having come loose. Or corrosion.

If all, or most, of these fault codes derive from a single electrical failure that is easily fixed, is it possible that that will then restore the AC to normal operation? Or is that more likely to be a separate issue? I know about the leaking evaporators and worn compressor clutch issues. A leaking evaporator sounds a bit unlikely considering the AC worked fine for at least 17 years, possibly 18-19. The same could maybe be said for the compressor clutch?

I have blown out dust and lint from the two cabin air temperature sensor vents behind the front door grab handles. I can hear a whirring sound from that general area, as from a small fan.

All suggestions and help appreciated!

• 126
  Passenger’s side interior temperature sensor open circuit or shorted to 12 volts
  
  134
  Passenger’s side air duct temperature sensor open circuit or shorted to 12 volts
  
  145
  Faulty signal from function selector switch
  
  151
  Signal from fan speed sensor missing or too high
  
  211
  Driver’s side damper motor position sensor open circuit or shorted to 12 volts
  
  221
  Passenger’s side damper motor position sensor open circuit or shorted to 12 volts
  
  231
  Ventilation damper motor position sensor open circuit or shorted to 12 volts
  
  233
  Floor/defrost damper motor position sensor open circuit or shorted to 12 volts
  
  235
  Recirculation damper motor position sensor open circuit or shorted to 12 volts
  
  311
  Driver’s side damper motor shorted to earth or shorted to 12 volts
  
  312
  Passenger’s side damper motor shorted to earth or shorted to 12 volts
  
  313
  Ventilation damper motor shorted to earth or shorted to 12 volts
  
  314
  Floor/defrost damper motor shorted to earth or shorted to 12 volts
  
  315
  Recirculation damper motor shorted to earth or shorted to 12 volts
  
  411
  Blower fan seized or drawing excessive current
  
  412
  Driver’s side interior temperature sensor inlet fan shorted to earth
  
  415
  Passenger’s side interior temperature sensor inlet fan shorted to earth
  
  417
  Passenger’s side interior temperature inlet fan seized

[Ben850]

So, You are reading with flash codes of course.

Clear those codes and read them again.

Are the orange lights for A/C and REC blinking when you first turn the key?

It is throwing enough codes to indicate it might not even be completely powered.
Check fuses 29 through 31.
Report back.

[granite]

So, You are reading with flash codes of course.

Yes. A few wires, an LED, a switch and some copper pins.
Here's the video recording I made of it (to make sure I didn't read any code wrong or missed something):

Clear those codes and read them again.

Will do!

Are the orange lights for A/C and REC blinking when you first turn the key?

Yes.

It is throwing enough codes to indicate it might not even be completely powered.
Check fuses 29 through 31.
Report back.

Ah, I never thought to check that. I figured that a blown fuse would make the entire system dead. No lights, fans or anything. I'll have a look later today and report back!

Thanks!

[Ben850]

Side note:,
To be able to read the codes accurately, if possible, all codes for that component must be read through. While saying ,"if possible", I mean the ECC unit may have toasted.

This may not even be the original unit, or power stage, and someone may have fiddled a bit.

I know something about that in dealings with my '96 Turbo wagon.
I will add some links as I find them.

W

[abscate]

A leaking evaporator becomes more likely the longer it lives, not less. I think you are about 2x the MTTF for this part. Once it warms up a bit, you can check your system for pressure.

[granite]

Side note:,
To be able to read the codes accurately, if possible, all codes for that component must be read through. While saying ,"if possible", I mean the ECC unit may have toasted.

Considering I got a lot of codes, I would guess all of it came out...

This may not even be the original unit, or power stage, and someone may have fiddled a bit.

No, I think this is the original unit. The car has had three previous owners. The first owned it for about twelve years, and had it serviced at a Volvo site every year. The second owner (an old classmate of mine) had it for about 5-6 years, and I doubt he would've "fiddled" with it. The third owner just drove it and had a mechanic take care of the few minor things that would come up. Assuming she didn't lie to me, she has never had the ECC serviced. It worked when she bought the car, and a couple of years later, it stopped working and she didn't care enough to spend the money on a repair.

[granite]

A leaking evaporator becomes more likely the longer it lives, not less. I think you are about 2x the MTTF for this part. Once it warms up a bit, you can check your system for pressure.

Fair enough, but I got the impression that this was one of those parts that either fails early on, or not at all (once past the first years).

I don't have the tools to check the pressure anyway. If it's empty, it's empty and that's that. End of story. But I'll check everything else first.

[granite]

It is throwing enough codes to indicate it might not even be completely powered.
Check fuses 29 through 31.
Report back.

All three fuses in working order. Nothing wrong there. No signs of corrosion in the fuse box either.

I haven't had time to reset the fault codes yet.

[jreed]

It might be a good idea to take a look inside the ECC unit to see if there are signs of capacitor or diode failure. There is a good illustrated write up here that shows more:
https://www.matthewsvolvosite.com/forums ... =1&t=58028

[abscate]

A leaking evaporator becomes more likely the longer it lives, not less. I think you are about 2x the MTTF for this part. Once it warms up a bit, you can check your system for pressure.

Fair enough, but I got the impression that this was one of those parts that either fails early on, or not at all (once past the first years).

I don't have the tools to check the pressure anyway. If it's empty, it's empty and that's that. End of story. But I'll check everything else first.

They fail on time. The corrode out either internally or externally and the Freon leaks out, which then kills the rest of your AC.