Hey Guys,

I am trying to troubleshoot my AC. It has stopped blowing cool and I need some help.
I went to the auto store and got one of those recharge things and it did not help. In fact, it acted weirdly. I will describe below.
Also, the compressor kicks on for a second or two and kicks off. It never stays on; just on, off, on, off, on, off.....and that happens as long as I have the air turned on.

Recharge:
- Started the car and turned on AC at full blast (not cool)
- shook the canister
- plugged it in and it said that it was empty
- pulled the trigger and watched the gauge, tilting the can to keep the mixture in the can fresh
- when the compressor turned on, the gauge when drop all the way to 0. When it turned off, it would go back up. I keep putting some in until it read full (in the green) once the compressor kicked off for a second.
- The whole time, the air never got any cooler.
- worried about over-pressurizing, I stopped and turned off the car. The gauge on the tank went into red.
- concerned about this, i drove home to see if it would level out. It didn't. I released some of the pressure until the gauge read green again.

What should I look at next? could there be a bad sensor that keeps the compressor from staying on? Is there a fuse to check? etc.
Any insight would be very helpful. This is my first AC troubleshoot and I will admit I am not expert in its operation or mechanical jargon. So please keep that in mind if plan to provide an explanation for something.

Thanks.

 

It sounds like your AC system is still low on refrigerant. I suggest you visit an authorized AC repair shop to have it troubleshooted.

 

What he said, have a professional look at it.

 

Relying on those gauges that are sold with Freon cans is an exercise in futility most of the time because you don't get the whole picture of what's going on with your AC system. You only get the low side.

If you want to learn how to work on this yourself, first and foremost buy yourself an A/C manifold gauge kit. You can find them on amazon for <$100. The gauges will come with instructions on how to connect them. Once you get that, get some High/Low pressure side readings and post them back here.

You'll want four sets of readings.
1) With the car off and the A/C having sat off for at least 30 minutes.
2) With the car on, the A/C 'ON', and the Compressor turning.
3) With the car on and the A/C on but, the compressor is 'Off' - You can get this reading if you simply turn off the A/C but you really want to watch what your Low/High side do when the compressor cycles off.
4) Lastly, turn the car off and let the A/C sit for a while. How long does it take the High/Low sides to show the same pressure level?

Depending on the readings it can point to different things. I won't get into troubleshooting just yet.

Couple of things you can check without the gauges, Radiator fan kicking on when you turn the A/C to on? Any stuff stuck to A/C condenser that sits in front and low on your radiator? Typical bugs is OK k but if it' completely blocked, that a problem.

You can have a shop diagnosis. It's usually $60 or more depending on how play. Some will charge a regular labor hour to diagnose which means it will cost you at least an hour of labor, whatever that is. Others will discount the diagnosis if you have the repairs performed there. They will then simply credit the diagnostic fee towards your total repair bill so technically the diagnosis was free.

 

Thanks for the info Derf. I will see what I can find. Last I looked the radiator was clean, but I didn't climb under the car to see if the compressor is beyond what I can see attached to the serpentine belt.

 

No worries. I fixed item 2. I had previously stated AC off and the compressor turning. AC ON and the compressor turning is what I meant to say. If your AC is off and the compressor is running, that's an electrical issue not AC flow system.

 

you only want to read the gauge on the canister when the ac compressor is running or else you will over charge the system, ask me how I know lol. read ALL the instructions. good luck

 

I knew what you meant. But thanks for clarifying.

 

That is the odd part though. When the compressor kicked off, it pressure gauge would go way up. I was worried that I was going to blow stuff if I added any more.

 

Like bl817 mentioned. You only want to read the low side gauge when the A/C is on in this case because you have no high-side readings and are trying to diagnose with half the information. High low-side readings are normal if the AC is off. I will not get into explaining that here. Do not try to charge the A/C system with the AC off. That is the number one reason why people end up overcharging their system.

Now, If your low side goes up when the AC is ON it can be a number of things.

I hate to post this here without proper readings but, here's what I'm talking about.
https://www.sanden.com/objects/SANDE...OSIS_CHART.pdf

If the low-side is high with the system On., System overcharge is only one possibility. Without seeing the high side reading, you don't know if its actually overcharged. a Failing/failed Expansion valve, a clogged condensor, or a problem with the cooling system of the car. There's a way to test for all that but only IF you have a set of AC manifold gauges to get readings.

IMO stop mucking with your system at this point unless you plan on getting a gauge set and learning how to use it. You're just going to be wasting your time and possibly causing more harm than good.

Take it in for a shop to professionally diagnose.