2007 impala ac issues

[MelancholyImpala]

Brand new to the forum, how's it going everyone? I'll preface this with saying i have done quite a bit of my own mechanic work however ac is something i have never really gained a knowledge base on. I just JUST bought a 2007 impala and for the first week the ac worked great then after that the ac would not kick on, the ac light would blink 6 times or the light would turn on for 5 seconds and off for 5 seconds so on and so forth without the compressor kicking on.

Today I was looking under the hood while my friend pressed the ac button and behold, the compressor kicked on. Following that about 8 seconds later something in the front of the car gave way and a huge cloud of hissing refrigerant erupted from the vehicle. When the cloud settled there was a tiny puddle of green dyed ac oil on the ground under the car.

I have ordered a blacklight and glasses to look for the dye specifically but I suspect in the cloud it was flung everywhere and will be hard to identify exactly where the eruption came from and also what the initial problem was in the first place.

What do you guys think could have happened and what should my next steps be to resolve this?

[MelancholyImpala]

are there pressure relief valves on car ac systems?

[JohnHere]

Yes, there are pressure-relief valves on mobile vehicle A/C systems that will release refrigerant and oil, as you experienced, under conditions of excessively high system pressures. The blinking light indicates a problem as well. Do you have any record of the A/C system being serviced by the previous owner(s)?

[MelancholyImpala]

I don’t have any service records of the ac. From what I have been able to agather the most common fix for the light on these cars is a low refrigerant charge however from the blowoff I would assume it was high.

[MelancholyImpala]

I have found the high side port and there is still pressure and quite a bit of it inside of the line. Is this a good sign since both the port lines are holding pressure? Maybe i just need a professional vacuum and refill of the system?

[JohnHere]

Often, when a HPRV opens for whatever reason, it doesn't re-seat properly and will continue to leak, at least a little. I would replace it at this point given the age of your car.

You'll need to determine why it released in the first place. As suggested earlier, a condensing problem is a primary cause of high pressure. Check for debris build-up on the front of the condenser (dirt partially plugging the fins, bugs, leaves, a plastic bag, etc.), as well as the operation of the condenser fan(s).

If the car spent most of its life in an area in which chemicals are used in winter to melt road ice and/or near the seashore, the spring and piston of the HPRV could have corroded badly enough to fail and release. A low-mounted compressor also contributes to corrosion due to road splash.

Along with the loss of refrigerant, some oil also came out. How much? None of us can know for sure. On recharging the system, you could guess, put in an ounce or two, and hope it's enough. If it's not enough, the risk is oil starvation to the compressor and eventual compressor failure. If it's too much, cooling might be compromised.

The only way to add the precise amount of oil back in is to start with a completely empty system: Drain the compressor, flush all old oil out of the components that can be flushed, replace the rest with new parts, then add the correct amount of oil to the compressor and components, reassemble everything, and evacuate/recharge according to spec.

[MelancholyImpala]

this is not a salt area vehicle and I'm under the impression that it was severely overfilled to begin with. I am thinking that it is possible that the safety shutoff that keeps the compressor from kicking on during an overfill scenario is malfunctioning and that may have caused the overpressure in the system, however i could be very wrong in that. With the refill i was going to have a full evacuation, vacuum test, reoil and refill.

[JohnHere]

...I'm under the impression that it was severely overfilled to begin with.

Lacking any service records, an overcharge is another possibility. Who knows what was done to it in the past. Could even have sealer in it, which can clog things up and cause high pressures.

I am thinking that it is possible that the safety shutoff that keeps the compressor from kicking on during an overfill scenario is malfunctioning and that may have caused the overpressure in the system, ...

I'm not sure what kind of HPCO switch your car has, and I don't recommend just throwing parts at a problem. But if the HPCO is relatively inexpensive, you could replace that before having it professionally serviced. I'd still replace the HPRV, too, at the same time. Cheap insurance, I think.

[MelancholyImpala]

I did not get a very good observation of the noise the compressor made but it did not seem loud or grumbly at all. For the time it ran it appeared to run well until it popped the relief valve and let a bunch out.

[MelancholyImpala]

Could it still be overfilled after the relief valve has opened? I could imagine it only relieved it to a maximum safe level in the lines not particularly the correct amount.