volvopentaman

Did some testing indoors, and noticed that the heat regulating valve for right-side doesn't seem to work (N176), had no sound, when the VAS5054 test program was switching it on/off, while the N175 for driver side had a sound.

Also, i've had sporadic error code from left rear footwell heater, but it just comes on occasionally, and the right side heater too has a code, and it had a burnt fuse. I took the test for them, they have a 25Amp fuse (right-fuse block nr33), right one was drawing 31amps of power, while the left one took 19amps. That's why the blown fuse. I'd like to know what causes this. I'll need to consult my wiring diagrams from the ETKA to know all connection points.

The weird thing is that i'm also not getting almost any heat to the rear of the car, not from any of the rear vents (floor, center, door).

If i'm doing my reasoning right, the N176 regulates the coolant passage to the right heat exchanger, and because the exchanger doesn't get hot due to malfunctioning N176, the ECU doesn't want to turn more fan speed on, due to more inefficciency, because the air coming to the cabin only get's cooler. This N175/6 valve problems seems to be a typical problem for these cars.

Shall try to continue tomorrow, to get to the bottom of this P.I.T.A

volvopentaman

Had the circulation pump&valve unit apart today.

Connected bottles to the engine heater hoses, and ran engine, coolant is flowing and coming out, so the engine circulationpump is assumably OK (at least on idle) 1L of fluid in a couple seconds.

The valves clicked, when powered, and the pump motor also ran fine, and no clogging. The coolant flows through, atleast when it's not powered.

So what could be wrong? still not enough heating power...

MP4.2+6.0

Getting down to where maybe you have to conclude the heater core itself is blocked (but not leaking. I get the sense from other tests you have done that the basic engine thermostat is working--as in, not just stuck open where it would take a long time in cold weather to warm up. Correct?

I've had a clogged engine radiator on an old C3 that similarly I could only diagnose as such after eliminating the other stuff--thermostat, fan set up, etc. Any chance you could fit a clear piece of plastic hose in with the heater lines somehow--maybe just temporary by using a straight coupling and a short length of extra hose w/ some clamps? Then you could see if it is actually flowing with the system closed up. Or, The old variant of this when you could reach the lines and underhood space was much more open was simply to see if the return line shortly after start up when the heater would have kicked in feels at least warm to the touch.

volvopentaman

The thermostat is working, and the engine heats up to 90ēc in around 7-9km as usual, and stays there. The thermostat is under 2years old. Tough, the front radiator hoses get quite warm, around engine temperature, even tough the engine isn't yet hot.

It's always taken ages to get heat out of this car, compared to my volvo's. Even the puny 340DL with a renault 1,4 engine was from another planet heating up, not to mention the 2,5L 16v unit, or the 3,0L I6 in the S90. They all warm up to driving temp in 2-4km (2km if +20ēc and 4km if started from -20ēc). The audi takes 7km from 20ēc even with a new thermostat, and 9km if started from below 0ēc.

Just ran the car up to around 50-55ēc engine temp, and checked the heater hoses. The engine hose and the incoming hoses to the heat exchangers are both near engine temp, I'd say 45ēc, and the return hoses are around 15-20ēc, so the heat exchangers are doing their work, even tough the heating isn't doing any good work.

The mystery is, why haven't i got enough heating power?

Or is my thermostat just bad, and letting heat go to the front radiator instead of the heater cores? But why would the eninge then heat up as it did with the new thermostat?

I'd need a complete coolant flow diagram, but haven't managed to find one yet for the W12, all just V8 models.

This is frustrating, as if the temp drops below -10ēc, you have to have extra clothing and stop every 50-100km's and use the webasto pre-heater to get the cabin even near warm.

Tough, now even the webasto has started to loose it's heating power...

mishar

Could it be that your cold and hot air flaps are not working properly so you are getting too much cold air. Have you checked temperature sensors? Sorry if you already covered all this. Tread/problem last for too long for my memory and I am too lazy to read it again.

volvopentaman

I'm suspecting the air flaps, as when i put the climatronic unit into test mode with my VAS5054, i got proper heat out of it (only momentairly, as it switches every actuator on/off/on with a couple second interval).

The weird thing is, that all the actuator sensors give right readings, so this would mean it's a program problem of somekind...

Could it be i have some basic setting stuff wrong in the climatronic unit? (I don't think i've touched that at all)

mishar

Is it same when you switch it to the air recirculation?

volvopentaman

Nothing so far adjusting the a/c unit has yeilded temp rising, NOT the circulation in any great amount (maybe a couple degrees increase in temp at max), nor putting it in "econ" mode = NO a/c, or requesting LO/HI temp or something between, or putting the blower on higher speed.

The weird thing is, that sometimes when i put it into "HI" it gives the same air temp coming out with same blower speed, another moment it gives cold air with full speed (auto mode). Same thing in "LO" mode. No matter if i request 16ēc, 20ēc or 28ēc, same problem.

Just can't get hotter air than 40ēc coming out of the driver's side vents even in a good moment and 20-25ēc from passenger/rear no matter what i do.

I just don't understand where the heat goes, if the core return pipes are cold, and ingoing warm, and no heat coming to the cabin... where is the heat going, to the moon? Or is the A/C compressor running at full, even tough i've put it into "econ"?

The weird thing, was that the a/c was also not working too well in the summer... could it be a stuck a/c compressor clutch?

If i put the temp in my volvo's on max, i get like 60-70ēc out of the vents. The audi has never given such temp.

mishar

Good question. Is ingoing pipe hot or just warm? And again: recirculation? No fresh air at all.

volvopentaman

Ingoing pipe(s) are all warm (around 45ēc) with an engine temp of around 50ēc (didn't have time to heat it up more this evening).

So if the ingoing pipes are warm as i said, and outcoming totally cold, the heat must go somewhere. Could it be that the A/C is cooling it down, and that the A/C compressor is running, even if it shouldn't be running, because of a stuck clutch?

I've only had problems with clutches worn too much on the a/c compressors, so they don't engage at all.