Automotive Air Conditioning Information Forum

I have a similar issue. 2012 fiesta

Last year I got this car. hooked up ac gauges and it was high... don't remember how hi but remeber thinking it's overcharged. So had an opertunity to hooked ac machine up to it and evacuated. Pulled a vacume for 20 min. Then let it sit and it held a vacume. So charged system with 1.124lbs.
Ac worked great for about two days. temps dropped so I didn't do anything with it till now. So I put gauges on it with car off and pressure on both sides is 205. It's 75 today.

How does pressure go up? No one else has done anything to car since last year.
Pressures are 125 on low side 310 on high side when car is running, compressor engauges and pressure drops to 60 low side and 425 high side.
Looking at numbers I think overcharged...but I know there is only 1.124lbs in system. So what else would cause pressures to increase? Is there a way compressor could pump air into system? But I don't see how it wouldn't leak out then too.?.

Anyone have any suggestions?

1. Much better to have started your own thread, it will get more notice that way
2. Vacuum for 20 min is almost like no vacuuming at all....should be 1 hr
3. Speaking of air, you probably did get air in system when you charged it
4. how were you able to weigh the charge

Started new thread here.

Ccweb1 wrote: ↑Fri Jun 24, 2022 6:06 pm So I put gauges on it with car off and pressure on both sides is 205. It's 75 today.

With those very high static pressures, it's either grossly overcharged or something is wrong with the Manifold Gauge Set.

Thank you for the replys I appreciate your inside. As I deal with mostly new systems and never get the opertunity to deal with trouble shooting and diagnosing used vehicles.
My experience mostly comes from installing red dot units in industrial machines. Threw work we received a MACS certification. But have very little to no experience with automotive.

The ac machine I used to pull a vacume and charge car was a snap on unit...I dont remember the modle, its the machine i use at work. I could possibly try and use the machine again but I'm sure work would not approve.
I'm not disputing my manifold gauge being bad but I can say I used it an hour later to check pressures in another car and everything was reading as expected.
I'm baffled how I can charge system with 1.124lbs and now have 205psi...how did system gain that much? I can't remember...it was a year ago but I imagine after charging the system was around 75-80 psi.

Again I appreciate the insight. And the help diagnosing the issue. Any troubleshooting guidance or things to check...I'd be greatful.

Then be suspect that there is air in there....

You intimated that you have confidence in the accuracy of your Manifold Gauge Set. So I think the way to go now is to recover the charge or have it done, and then—while the system is empty of refrigerant—replace the receiver/dryer. They're inexpensive. On your car, it's a traditional canister separate from the condenser, but it is attached to it.

After re-assembling the system, evacuate it for at least one hour as already mentioned and re-charge it to specs. I sometimes evacuate overnight if possible to ensure that I get out all the air and moisture. If you're having a shop recover the charge, you could bring it back to them for the evacuation and re-charge after you replace the R/D. Or, just have them handle the entire job.

The refrigerant specs that I have differ slightly from what you posted: 19 ounces net weight (1.188 pounds) of R-134a. The oil specs are 3.4 fluid ounces of PAG-46.

Refrigerant, air, and moisture—a bad mix for any A/C system, that's for sure.