So my AC is super cold when my engine bay is also cold. However, when my engine bay is hot, the blowing air isn’t so cold anymore.
In other words, if the car has been off for 6+ hours and hasn’t been in the sun, meaning the engine bay is at normal temps, all good.
If the car has been running for a while or if it’s been off but sitting in the blaring sun, the air isn’t so cool.
Any thoughts?
I actually have a VERY similar or same problem. I initially thought my compressor shit the bed because i hardly ever use A/C. After driving the piss out of the car it began to rain, so i turned the A/C on because the window was fogging and low and behold it was hot. Not cold at all. A few weeks later it i turned it on again because of rain but it was fine. Over the weekend, i was driving the piss out of it again and once again hot.
I noticed this time though that once i let the air run for a long time and on defrost the air eventually (long time like 20-30 mins) it went cold.
Something else i noticed, maybe with yours as well? if its blowing the hot air, i noticed that my car gets cooler on the driver side first before the passenger. the vent closest to the driver door is always the coldest one (though not that cold) and i can feel it try to become colder over time. Meanwhile passenger vents are hot.
Edit:
forgot to mention what it could be. Someone told me that there is a valve up on the passenger side engine bay area. (not exactly sure where but i was told its easy to get to). Basically i was told this valve is getting stuck and not allowing the cold air to get into the cabin. Similar to a thermostat getting stuck for the engine. Someone with more knowledge might be able to answer.
For the bolded part, does the air get cold after you start moving for a little bit?
I have noticed what you said. It seems like the AC condenser can’t get enough air flow to cool it off at times until I get moving. I sat in traffic at times on my trip and the AC would blow hot after a minute or two of sitting still. So I would turn the AC off and roll all four windows down until I was steady moving. The oil and coolant temps would also raise quickly while sitting in traffic with the AC on. The heat exchangers for the SC oil cooler and power steering probably heat up the AC condenser.
My situation is very similar if not exactly the same as FastEddie’s description. Colder on the driver’s side as well.
I admit I haven’t waited 30 minutes with hot air blowing at my face on a hot summer day to see if the air finally gets cold again though.
Ultimately, it only blows cold from the get go if the car hasn’t been run in a while and the engine bay is nice and cool. This morning, the air was cool to begin with until halfway to work it started getting warmer again (passenger and middle vents warmer than the driver’s side vents).
I think we’re experiencing the same thing. Now, how do we fix it? My compressor is brand new so I’m leaning toward something else.
same here
I have no codes, the econ light isn’t coming on…just the AC isn’t awesome when it’s piping hot out. It’s like it’s losing a battle.
Just happened in the past few weeks. Our cars are pretty old and a few friends with RS4s are going through similar symptoms.
I first notice it on mine while going 80 mph on an expressway for 2 hrs. There was like a switch was flicked and it got hot and humid in the car. Not like it died…but like it went from 100% effective to 50%.
It returns to 75% sometimes, and gets as bad as 25% sometimes, but never dead, and never perfect.
No idea what’s going on. Hottest summer I can remember here though so it’s not ideal lol. At least I made it to mid August before these symptoms.
This happens to me too. You can get cold air flowing again by turning on the recirculate function. It improves if you slow down and turn recirculate off, but doesn’t really “fix” until you stop and restart the car.
Axel,
Questions:
When you replaced the compressor, did you replace the dryer & orifice tube?
How did the compressor fail? - As in, could there be any trash remaining in the lines?
Was the system exposed to air for any significant period of time?
Your fans are all working, correct?
Who did the vac/recharge? Did it hold vac?
Are you sure it’s not leaking?
Have you put a set of gauges on it?
I posted a part number on here awhile back. I dont remember what thread. ill dig for it. I had someone tell me that this valve is getting stuck and not letting the cold air come in. the area where the valve is ,is somewhere behind where the two ac lines run into the firewall area near the battery in the engine bay.
Here is the post i found.
part number is 8K0820679B. Europa parts has one right now for 60 bucks. BUT the OEM part is like 180 i believe.
edited with link.
https://www.europaparts.com/a-c-expansion-valve-8k0820679b.html
Almost seems to good to be true. Let me know what you guys think
^^interesting that they list the B7 S4. Please correct me if I’m wrong, but I don’t believe the B6/B7 platform used an expansion valve. Just an orifice tube. They perform similar functions.
The original compressor was leaking. All fans are working. My indie shop who is the only one that touches my car did the vac/recharge. They didn’t express any concerns or issues during the process. I’m guessing if the system was leaking again, I’d be out of fluid (again) and it would completely stop working (again).
Seems like this isn’t so uncommon with our cars? Strange. Might ask my indie shop to look at the system again. Haven’t been back to see him since he replaced the compressor.
[quote=“Axel,post:12,topic:8939”]
Okay, just covering all the bases. Ask them if they changed the orifice tube. If they didn’t, I’d bet a buffalo nickel that’s it. When they replace it, they’ll vac out your existing r134 so you’ll also know if you’ve lost any as well.
I have no idea. Just posting what i saw lol.
I was having the same problems you all are describing until one day it just quit altogether. pulled out the orifice tube and it was full of metal shavings. new compressor drier and orifice tube is what solved my issue lol. air blows ice cold sitting in a traffic jam at 40 degrees Celsius now.
quick way to check if its your compressor is to evacuate the system and pop the orifice tube out. if theres metal your compressor is on its way out.
What if it’s a brand new compressor? Could something else be causing this other than a compressor on its way out?
-Moisture in the system - The dryer can only absorb so much water until it’s no longer effective. If the system was open while the compressor was being replaced and there was any humidity in the air…makes it pretty suspect. If it’s original, just replace it as preventative maintenance.
-Clogged orifice tube - Can become clogged over time even if the compressor is in good working order.
-Debris on the condenser fins obstructing flow.
Were I in your position, I’d replace the orifice tube & the dryer, then recharge. While replacing those bits, change the seals at their connection points as well.
It is easy to access this? I know the compressor is nightmare but if the other parts are accessible i may try this in a few months when i have more downtime. The parts shouldnt be much correct?
Where the high & low-side lines meet at the firewall. You’ll un-bolt that block and the orifice tube will be inside. IIRC you grab it with a needle-nose and it may need a slight twist to get it out. Just be careful not to break it. Buy the parts first so you know what you’re looking at. The dryer is in the passenger side fender.
JHM lists the orifice tube on their site but not the dryer. Give them a call and I’m sure they can source one for you as well. Those guys have a wealth of knowledge on our A/C system as well.
recharged my RS4 air conditioning system last night with the help of BadToyz who already had the hose/gauge. Just needed a can of ‘stuff’.
Now, this may be a temp fix…if there’s a leak I will lose that gas slowly and need to re-do, at which point I’ll go deeper and do the evacuate/dry/sealant service then recharge.
We left the car runnign with AC full blast during the fill, and when I got in the car after shooting the shit for 5 minutes it was ridiculously cold. Meat locker.