AC troubleshooting

So the AC in my 2011 has stopped blowing cold, pretty much zero temperature difference between AC on or off. Doesn't seem to be any of the actuators, not hearing or feeling any type of clicking from any of them. Having no issues with airflow switching from vent to floor to defrost. Also having no issues on the heat side, so I'm thinking the blend actuator is working.

Grabbed a cheap manifold gauge set tonight and took some readings. I'm thinking I'm low on refrigerant but want to get the opinions from the experts here. Thanks in advance for the help!

When all readings were taken, it was 80 degrees outside after sunset, car was parked in covered carport all day. Humidity was 68%.


Engine off and cold.




Engine running and warmed up, MAX AC on for 5 minutes.




Engine running and warmed up, AC off.

Yep. Low on refrigerant. Your low side pressure is low. Should be closer to 35-40 at that temp and your high side is also down. Should see at least 200 for that ambient.

The engine on, A/C on pic indicates a refrigerant undercharge. You have a leak, but it's a small one. The most common culprit is the A/C condenser, as it sits in front of the radiator and is thus subject to being impacted by small road debris.

Well, after trying to top off the system tonight, I think I'm going to take it to a pro for diagnosis unless the video below showing my gauge readings while the car is running leads to an answer.

I grabbed a can of refrigerant today, connected it to the manifold gauge and purged the air out of the supply hose as instructed. With the car running and warmed up and the AC on, opened the low side manifold valve for 2 seconds and closed it. Watched the pressures while letting the car running for 5 minutes. Pressures were about 20 on the low side and just under 200 on the high. Opened the low side manifold valve for 2 more seconds and closed it. After 5 minutes the low side pressure was sitting at almost 30 and the high side got up to 250. I did not add any additional refrigerant after that point.

As you'll see in the video below, the high side sits pretty damn steady at about 250. The low side will creep towards 30 and the cooling fan will kick on. About a second after the cooling fan kicks on, the AC clutch disengages, the low side pressure climbs to about 95 and then the AC clutch reengages and the low side drops rapidly, getting almost down to zero before slowly climbing again. It then repeats the exact same process.

I'm hesitant to continue charging the system because it seems like something else is going on here besides low refrigerant. All fuses and relays have been checked, outside temp is 83 degrees with 68% humidity. The lowest air temp I'm getting out of the vents is 79 degrees.

https://youtu.be/mtozKA_-dNU

One additional update to my post above, while waiting for input I decided to double check all the blend door actuators. I am getting a very slight double click out of the panel vent/defrost vent actuator when I switch from defrost to vent position. Airflow is transitioning fine from the defrost to vent position, just getting the double click when I switch from defrost to vent, no clicks when I go from panel vents to defrost.

That can't possibly be causing this issue could it? I've been thinking about this for the past two hours and can't wrap my head around how that could possibly be the cause of the AC problem.

Did you inadvertently close the valve on the high side gauge? It should be moving. Pressures equalize when the compressor isn't running.

RazorbackMustang said:

Did you inadvertently close the valve on the high side gauge? It should be moving. Pressures equalize when the compressor isn't running.

Click to expand...

I very well may have, thought about that after running the same test on my F150 late last night just so I could see what a properly running system looked like. Going to rerun the test here in a little bit after dinner.

It turns out that I did somehow bump the high side coupler valve shut during my initial tests. I ran through all new tests tonight, the sequence is below. All readings were taken starting with a dead cold engine (car engine had not been run in 18 hours, sat in a covered carport, outside air temp 80 degrees, humidity 68%)

This is the pressure in the system with the engine off. Left the gauges connected while starting the engine, no change once engine was running with the AC turned off.



This video shows what happens when turning on the AC for the first time since the picture above, engine has fully warmed up.

https://youtu.be/ZYeBDoFPrEU

This pic is 5 minutes after turning on the AC as seen in the above video. The cooling fan has not kicked on yet.



A couple of minutes later, the cooling fan kicked on, pressures dropped to these levels, fan kicked off and they started rising. Fan kicked on at about 25 psi on the low side



This video shows what the pressures do when I turn the AC off after the above readings.

https://youtu.be/3h8vgWfj3wM

This last pic is where the pressures are 2 minutes after turning off the AC, engine still running. They did not change at all after turning the engine off.



End of the day, I'm still blowing warm air, thinking I have a significant refrigerant leak at this point since I did put about 6 ounces of refrigerant into the system last night.

I can't see any of the pics, it's taking me to a woodworking website?

RazorbackMustang said:

I can't see any of the pics, it's taking me to a woodworking website?

Click to expand...

Shit, fixed it. You should be able to see the pics now.

Ok, at this point, I'm going to say there may be a blockage in the orifice tube. Low side is showing too low and high side in your pics and video is too high. 275 is too high. Especially since you're not getting cool air at all. You should see a maximum of mid to lower 50s (still too warm IMO).

When charging, were you charging liquid or gas? You should only charge gas. Can upright, don't shake it.

RazorbackMustang said:

When charging, were you charging liquid or gas? You should only charge gas. Can upright, don't shake it.

Click to expand...

I charged with the can upright.

Bit of an update, after chatting with a local AC tech, I went ahead and charged the system some more. Dumped a 12 ounce can into the system and I'm now getting 38 degree air out of the vents. I guess now I need to start looking for the leak...

And yes, I do realize that is probably no longer tech and is actually idiot car owner that can't read a gauge set properly. I will make the appropriate corrections to said idiot car owner....

LB75 said:

Bit of an update, after chatting with a local AC tech, I went ahead and charged the system some more. Dumped a 12 ounce can into the system and I'm now getting 38 degree air out of the vents. I guess now I need to start looking for the leak...

Click to expand...

Did you put any dye in the the Freon? Makes it much easier to troubleshoot with a black light

LB75 said:

Bit of an update, after chatting with a local AC tech, I went ahead and charged the system some more. Dumped a 12 ounce can into the system and I'm now getting 38 degree air out of the vents. I guess now I need to start looking for the leak...

Click to expand...

Curious. What are the pressure readings? Low charge is denoted by low gauge readings on both, not just the low side. I wonder if the gauges are reliable?

Regardless, I'm glad you're sorted out.

86GT351 said:

Did you put any dye in the the Freon?

Click to expand...

Freon? Let's hope not.