I’ve noticed since I got my A5, that the rad fab runs just about the whole time I drive the car. I find as soon as the temp gauge comes off the bottom is when they start going. My car never quite hits full operating temperature. I checked with vcds and it stays at around 70C on all of the coolant temp measuring blocks I could find. Its about 5C outside so the cooling fans shouldn’t even have to run most of the time. Is this normal?
Do you mean on your A6 or S6? On the S6 this means that the fans are failing or connections to the fans are failing, which eventually begin to drain the battery.
If you have the defrost on your running the AC compressor and when the AC compressor runs so do the fans. This might be the issue due to the outside temps and you running the defrost…
Sorry. Meant to post this under a5
This is the A5 section…
Yes I accidentally posted this under a6 originally then changed it
A small update: thought I’d let it warm up for a couple of minutes this morning and noticed that the rad fan kicks on about 30 seconds after start up, when the car is dead cold. I turned off the heat, all the hvac fans and didn’t change anything. I’ve read about people having bad coolant temp sensors that can cause a similar issue, anyone have a similar experience?
Coolant temp sensors or even a thermostat on its way out. One thing, and it’s rather strange. I live in Central Texas. It gets damn hot. I can go out for a drive, pull in my garage, shut the car off and no fans. As soon as it drops below 70 degrees, the fans come on and usually run a bit after shutting the car off.
Engine oil temps also run hotter in winter than they do in summer. Reverse logic I know. On a 100 degree plus day, I see temps around 203-206F. In winter, it’s 225F+.
So today, my ambient air temperature sensor started functioning ok, and it might be just a coincidence, but my cooling fans didn’t run all the time. That being said, I was still only at about 70 degrees. I turned the heat off when I was cruising and was able to get 5 more degrees or so. Turned heat back on and temp dropped pretty quickly. I felt all the hoses and they weren’t very warm. So I’m leaning towards thermostat, but I imagine there still could be an issue with the coolant sensor
The thermostats are a know issue across the A4 and A5 line. It happens frequently enough that we hear about it on the forums yet most are unaffected. So definitely something to look at.
You’re logging with a VCDS?
I have vcds, what measuring blocks should I be checking?
Here’s an update. I replaced the whole water pump/tstat/temp sensor assembly. Also carbon cleaned intake. When I pulled the spark plugs I noticed they were pretty dark indicating car is running rich, so maybe it was on the warmup map all the time. Car runs a whole lot better now in terms of performance & fuel economy, also gets up to proper operating temp. I was lucky to get 9L/100km at 100kmh, now I can hit 7L/100 on the same drive.
Valves now look great! Glad you’ve solved the issue. Dunno what it is with Audi and thermostats…it’s a big issue on the B9 cars.