stylo_guy

- 2007 LS
- 2.2 liter EcoTec engine
- about 101k miles
- auto trans

So I recently replaced the AC condenser (old one was leaking) and also replaced the infamous/crappy GM "ball" service port (the one prone to leaking) on the high side with a proper shraeder valve version. This was in response to my last visit to the shop, where I instructed them to leave the system "empty" so I could work on the parts

Took it back to the shop after replacing the parts in question (AC condenser and high-side port), they recharged and tested it for leaks - it passed the test and they said it's holding pressure. They also filled it with leak dye and instructed me to come back in 2 weeks to do a recheck for leaks, which I did - and it also passed the leaks inspection the second time

But I notice the AC doesn't "feel" as cold as it should, or maybe it's a perception thing?? It's like, I get into the car and turn the AC on... but it just SEEMS like the inside cabin doesn't "start" to feel cool until like 10 minutes later, whereas in other cars I've sat in (especially big trucks and big SUVs) the cabin starts feeling cold-ish within like 2-3 minutes at the most

As for the air coming out of the vents, it feels cool... but not really "cold", if that makes sense

So if leaks are ruled out, what else is there to look at? Worn serpentine belt/serpentine belt tensioner? AC compressor itself?

For what it's worth, I did do some DIY experimenting and put the front up on jack stands (so the car wouldn't move) while my brother inside the car applied a little throttle up to around 3k RPM or so while the AC was on - and looking at my basic AC gauge set I noticed that the psi on the high-side seemed to drop when the RPMs go up, but when the engine is just idling/foot off the gas it looked like the high-side psi was "where it's supposed to be" according to that one chart posted here

Thoughts? I'm REALLY hoping it's not a dying AC compressor since not only are those pricey at $250+ but also I would then have to repeat the process of going down to the shop multiple times to have the system evacuated, order myself an AC compressor and install it, going back to the shop to get recharged, another return trip to the shop to recheck for leaks, etc

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donbrew

The first obvious question is: where is temp knob set? Did empty mean a vacuum? Was the system flushed and a new filter installed?
First I've heard of a valve prone to leaking. I have had 2 go 300,000+ with no AC problems.
Vac pumps are cheap/easy to make. Try your local pawn shops, Craigs list, ebay, aliexpress etc..

stylo_guy

Temp knob is set all the way to "max" cold, of course.

"Empty" means they (the shop) evacuated the refrigerant, during the first shop visit. Then I replaced the affected parts (AC condenser and leaky high-side service port) and came back for another visit, during which they recharged the system and checked for leaks.

The reason I opted to do the parts myself is because the shop quoted me like $900+ if they did it (replace AC condenser and replace high-side refrigerant line) - probably closer to $1000+ with recharge and taxes. So instead I just ordered the parts off rockauto for about $90 and change, and installed them in the parking lot

Didn't see anything about a filter mentioned anywhere on the shop paperwork. For what it's worth, I installed a new cabin air filter last month (August) so I don't think that's it. The new cabin air filter DID improve airflow noticeably (I estimate about 30% more air blows out now)... but the air still just feels "cool" rather than "cold", if that makes sense

firemangeorge

Until you put a set of gauges on it and get some readings, it’s hard to say. You need both high and low side readings. And stick a thermometer in the center dash vent. 38- 48 F. on a working system.

Oldblue

Try setting the system to recirculate, the button on the top right of the hvac control panel fan speed switch

stylo_guy

Yeah I've had it on recirculation, I just forgot to mention that earlier

​​​​​​The specific issue I have is the AC seems to blow cold when the car is idling/standing still... but seems to get weaker as the car accelerates and as torque kicks in/starts to get the MPH up 🤔

Googling around I didn't find much information on my specific problem - most of the Google results pertain to the exact opposite scenario (...the internet poster or complainant will report their AC blows cold when the car is moving/accelerating, but gets weak at idle/at red lights)

Earlier I happened to have my dongle scanner on me and decided to make a short video "showing" what happens with regards to high-side pressure when the car is standing still/idling (or even just slowing down) versus speeding up/accelerating. See here, it's about 13 mins long - the outside ambient/temperature at time of the video was around 69-70 degrees outside with humidity around 25%:
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"ac performance while car moving"

https://drive.google.com/file/d/1gDi...w?usp=drivesdk

Take note of the patterns in the video:

- car is sitting still/idling? AC pressure seems fine, is sometimes even a little higher than the spec outlined in the performance chart
- car is slowing down? AC pressure rises
- car is accelerating/torque is kicking in? AC pressure falls, sometimes rapidly
- take note that before the AC is even turned on (early in the video), the baseline psi in the lines is 99.5, and later on in the video at around the 6:40 mark the psi dips as low as 99.5 during a burst of acceleration... almost as if the AC compressor cut out entirely for a moment... then from roughly 6:50 to 7:10 the AC line pressure rises almost IMMEDIATELY as soon as I step on the brakes and the vehicle slows down, and then drops again as I accelerate from 7:15 to 7:30


The one common denominator seems to be that the AC line pressure falls as soon as the car begins to accelerate/as torque kicks in - but it seems to blow cold air just fine when the car is stopped (say... at a red light)/idling

Thoughts?

EDIT: as a side-note, besides a generic "B0081" seatbelt system code I noticed when loading up my dongle scanner, there were no other codes (either current or pending), and the check engine light is not on

RJ_RS_SS_350

Is that a typo? You say baseline is 99.5, then dips as low as 99.5.

I'm not sure what's going on with the video. When I tap play, it gets so small, can't see anything.

stylo_guy

No typo, that's what it showed in the data/video

The video works fine if you go full-screen, or at least it works fine on my phone. Full-screen selection button is towards the bottom-right

firemangeorge

Video doesn’t work for me. Doesn’t play. Says doesn’t support full screen.

stylo_guy

Could be the browser you're using.

I can confirm it works fine on both Chrome and Firefox, also tested the link on both my phone (Android OS) and my laptop (Windows) and the video starts right up on both devices

Just in case there was some sort of typo in the above link, here is a fresh copy-paste of the link:

https://drive.google.com/file/d/1gDi...w?usp=drivesdk