MP4.2+6.0

the surrounding air, and this is the sensor that measures the air temp you see on the center display for outside air temp. There are other sensors inside the car that measure what it sees as the inside temp to control the HVAC.

Galco

Thanks for the details! Will try to get this under extended warranty if not, looks like a DIY session is soon to be scheduled.

ohsigmachi

Does anybody have the Audi part number for this exterior air temp sensor? I don't want to be ordering the incorrect parts here. My 05 suffers from the same heat-soak poor A/C performance. I will also be using the A/C pro if the sensor swap doesn't cure the problem.

Galco

Hello,

Can anyone tell me the part name and number for this HVAC sensor at top-center of dash board close to windshield (see pic below - sorry couldn't get the rotation right)? I searched a couple of online parts suppliers but could not find this item. Your help is appreciated.

Following MP4.2 post I replaced the exterior ambient sensor behind the front grill sometime ago and while AC improved, my 2006 now has the symptom of not cooling as well once car is parked outside for a while compared to when first taken out of the garage. Suspect its the dash sensor and would like to replace it.

Thanks in advance.

Jack88

It's called a sun load sensor, you can buy one here, part #4E09075394PK. Are you getting any error codes?

MP4.2+6.0

Yes, sun load sensor.

So, completing my tale from the post you mentioned. Eventually my A/C got less and less effective even with the sensor changes. Turned out it was basic refrigerant charge. Had it done professionally. Full charge is something like 630 grams (not a lot on more modern systems like these); it was down by almost half. Done by weight these days. Recharged and all good.

PaulW on QW was doing the same things in parallel to me on his S8, and likewise found he needed the recharge to get it back up to snuff.

Junius

I wonder how to replace that sun load sensor?

richard-tx

My AC was not performing as well as it did last year so I took it to the local mechanic who I trust. He evacuated the system, and measured the charge. What I discovered was the it was down about 3 oz. He put in the 3 ounces plus a little oil just to be sure there is enough and now it is performing as it should. Set the climate control to 72-73 degrees and the car is cool and comfortable despite 100+ degrees ambient.

Galco

Thanks for the feedback, most helpful. I will try the recharge first and see if "under-performance" goes away and report back.

richard-tx

Over charging the system is as bad as undercharging. Over charge yields poor cooling performance. When mine was overcharged and it could barely make 65 degree vent temps. With a proper charge it is easy to attain 45 degree or lower vent discharge temps on the highway with 100+ degree ambient outdoor temps.