Hi was hoping any of you can point me where the low pressure service valve for the ac is. Just need to find out where to hook up the refrigerant i bought. I have an 01 a4 1.8t

 

Okay so i guessed which one is it and just need anyone to confirm if that's the low pressure ac port. Also i checked pressure and its at 65 psi. Isn't that a bit high or more than enough refrigerant? If so, what could be the reason that i'm not getting any cold air? Thank you.

 

also have this codes if it matters.

VCDS-Lite Version: Release 1.1
Thursday, 26 May 2011, 20:29:18.
Control Module Part Number: 8D0 820 043 P
Component and/or Version: A4 KLIMAAUTOMAT D57
Software Coding: 00140
Work Shop Code: WSC 06435
VCID: 2D2D8AB7F41F
3 Faults Found:
00779 - Outside Air Temp Sensor (G17)
30-00 - Open or Short to Plus
01274 - Shareware Version. To Decode all DTCs
41-10 - Please Register/Activate - Intermittent
00792 - Shareware Version. To Decode all DTCs
31-00 - Please Register/Activate

 

That is the low pressure port. If the compressor wasn't running and it was hotter than 50 degrees outside that pressure is low. If the compressor was engaged then its to high. If your outside air temperature sensor has failed like the program seems to indicate that may inhibit your compressor from engaging since the car has no idea if its 100 degrees outside or 0. most cars will not allow the compressor to engage if the outside air temp is lower than 45 degrees or so.

 

So what could be wrong then? Where do i start? Air temp sensor? What about the rest of the codes? Is this a diy thing or shoukd i leave it to a tech? Ty

 

Does the compressor run when you have the A/C on, I'm assuming with the codes you have that it does not come on at all?

The outside ambient air sensor is stuck in the back of the front bumper behind the center grille opening.

The 01274 is an air flap positioning motor v71 code has to do with one of the air doors under the dash not being in the right position.

The 00792 is a low pressure switch (F129) code in the A/C system. The pressure switch is a combination high low pressure riight of the radiator (left as you look at the front of the car) just below the edge of the bumper. Probably indicates that you need more refrigerant.

 

i must've mess sonething up when i did my timing belt. Probably wasnt able to put it all back. I did that last winter so i had no clue if i had ac till just this hot season. Anyway i'll take out the bumper and all that and check those pieces. So fault 00779 couldve trigger fault 00792? Anyway ill try and find out monday when im off. Thanks alot mark. Really appreciate.

 

No the ambient temperature sender wont affect the pressure switch code and the pressure switch wont affect the ambient temperature sender code. You don't have to remove the bumper to see either of these devices. The ambient temperature sensor is the same sensor that displays the outside temperature on your dash, its just stuck in a hole in the center brace behind the lower center grille, just pop the grille out and you will see it, the wire comes down to it from over near where the washer tubes come out from behind the radiator support on the drivers side. You can see the high//low pressure switch right over the top of the bumper edge just below the high pressure test connection on the passenger side of the condensor. You can access it if you remove the passenger side headlight.

 

okay mark first of all you're a life saver. Got my cold air back. What happened was my high/low pressure switch was unplug and i just had to plug it back in. I feel dumb lol. however i really couldn't find where my outside ambient temperature sensor is at. nothing on the location where you pointed it out. more pics for you. anybody else' opinion is very welcomed to. Thanks.

 

My sons sensor wiring harness is a 2 wire cable in a black plastic sheath with a white stripe on it. It comes around the lower left corner of the radiator by the drain plug, then it is wire tied to 3 or 4 other wires right infront of the oil cooler on the lower left corner of the engine and then goes up to a connector located just inboard of the power steering fluid reservoir on the front of the front wheelwell. Its on a bracket literally 1/2" from the side face of the reservoir. The sensor itself plugs into a bracket on the back of the front bumper, see that little grey spot on the lower core support about 3" from the edge of the condenser, thats where a cable clamp attaches to hold the harness up as it crosses to the center of the bumper. The sensor itself my fit into that hole in the middle of the lower core support, my son ripped the bottom lip of his bumper off in a snow bank this winter and it was just hanging under the bumper, I stuck it on one of the holes that hold the center grille on (see the hole on the left most vertical support just below the aluminum bumper support), it fits fine and works but maybe it doesn't go there.