Classic sticky RCV symptoms - Intermittent, slow to kick in A/C on hot days

[TurboABA]

On my 2010 with 180k miles on the clock, I'm starting to experience "delayed" A/C performance on some hotter days......
Eventually, the systems starts performing well, and although I haven't actually monitored\logged any measuring blocks and\or vent temps, I'm fairly confident at this point that my RCV is starting to act up.

I have the following questions from those who have dealt with this before (@oilhammer - I'm sure you've done plenty of these).
- Is this a "true" tale tale sign of crud in the system and\or a potentially dying compressor?
- Do I risk damaging the compressor if I prolong replacing it (I'm not only being lazy at this point, but winter is coming so "hot conditions" won't be around for a while)

It's not that I'm scared of the wrenching part, it's just that I actually have to take it to "some butcher" for this one since I don't have the equipment to evac\refill the system properly.....

Lastly, if anyone can quickly guide me to what measuring blocks I can monitor to validate my suspicions, I'd appreciate it as it will save me the searching that I'm about to embark on.

 

[oilhammer]

Well, this butcher thinks you need a new RCV. But I would make certain both fans are running. These fans are controlled via a pressure input, from the pressure sensor down near the compressor in the line, near the passenger side headlight. In some cases, the RCV is just so dead, it won't even make enough pressure to trigger the fans, but if you still have some cooling, there should be enough.

Just go into the HVAC module and start looking and the Measuring blocks, and you'll find the refrigerant pressure. They are not all in the same spot, so I don't remember off the top of my head exactly on your car, but there are not a whole lot so it'll be fairly low down (starting from Group 001). VCDS has it labeled, I've yet to run into one that wasn't.

Of course, a low charge will exhibit the same conditions. This is why I like to pay attention to the amount recovered. This can have a margin of error, depending on the machine.... I know my machine, so I know if the car says it holds 525 grams, and it says I removed 400 grams, I know the car was "full" before I messed with it.

You won't hurt anything by leaving it alone if it is indeed just an RCV that cannot function properly. You *can* hurt something if it is due to low charge, as the refrigerant also is what carries the oil around the system.

Most R134a leaks, though, are absolute. Meaning, if it has a leak, it has leaked out and the system is empty, and it won't work at all. We do a boatload of RCVs here.

 

[TurboABA]

Gotcha.... I know I offend people all the time, and you may refer to yourself as a butcher, but based on what I've seen from your posts, you don't qualify in my books...... but if you recall some of the finer people I've had to deal with, (aka my expert dealer who claimed that my ABS sensor flaky reading was caused by "rust pushing the sensor out of alignment" after 2hrs of troubleshooting on the insurance's "dime") I believe you'd agree with my "terminology".

Regardless, as far as I've noticed, it's not a pressure loss\low charge condition, and all works fine, with the exception of the intermittent "delay" on some of the hotter days.... which leads me to jump to the conclusion of the sticky RCV..... I'll poke around with VCDS a bit to see what current it's getting and if I can see significant differences in temps\etc across various components before I let these animals touch my DD again.

 

[Rx7145]

Classic RCV. May want to change the condenser as they are often damaged by small rocks over the years.

 

[TurboABA]

Classic RCV. May want to change the condenser as they are often damaged by small rocks over the years.

I'd rather do some troubleshooting and datalogging before I start throwing parts at it blindly....... even if that's frowned upon these days.

 

[sptsailing]

I have had to replace the RCV twice now on my car. The A/C works almost all the time now, but seems to require the engine to hit 2000 RPM before doing so.