Cole Peters

Hi everyone, I've got something that will put your brains to the test. My fiancé has a 2012 civic and the A/C acts very odd, while going down the road it gets ice cold for a few seconds and then gets warm like just a vent. I had the system professionally charged with a legit machine, and from there I had my old boss (he's an ASE certified master tech) take a look at it, he hooked up his pressure gauge to the low side of the system and it isn't supposed to get below 20 psi when the car is running with A/C on and it went all the way down to 0, therefore activating the low pressure switch and shutting the system off for a few moments until it builds up pressure again. Has anybody had any sort of similar issue? For some reason my gut is telling me it's the expansion valve but idk why. He looked up other people's repair information on his database and a few people needed compressors, a few needed expansions valves, and there was another listed that I can't remember. I just don't want to replace something and have it not fix the problem, if anyone can shed any light on this I would greatly appreciate it!

ezone

What about the high side pressure?
Low side pressure only tells half the story.
When the low side drops to zero, what is the high side doing?

Why didn't he actually diag this thing?

Based solely on your description, I can't answer as there is not enough info and more troubleshooting is needed.
"Could be" a lot of things.
Low charge, blockage, bad TXV, failing evap temp sensor (thermistor), etc.

If the system pressure SENSOR caused the compressor to turn off, did the actual system pressure at that sensor go low or high? (as read on the scanner data list)
The high side gauge should have read the same as the pressure sensor on the scanner data list if someone had checked this.
If the high side pressure truly goes to zero that would indicate a likely problem in one area, but if it stays relatively high then the problem is elsewhere. If it was high enough to cause cutout (450 PSI or so), that's yet another issue.

If the thermosensor in the evaporator core caused the compressor to turn off, that's a whole different story.

Cole Peters

We haven't thoroughly diagnosed the system yet because when I had him take a look at it he was busy with other things and just helped me out real quick. I was posting this question to see if I could get lucky and maybe this was a common issue with these cars and someone else had the same problem and could show me the right direction. I know for a fact the A/C charge is good because just a couple days before this I had him charge the system with a legit machine that evacuates and recharges the system, not just putting refrigerant in it till it has "good pressure". Both radiator fans are working correctly and the compressor is cycling as it should, but the system only runs for a few seconds until the low side drops to almost nothing and it cuts the A/C. I figured it could be multiple things so I think the best thing to do is have him legit diagnose the system. I was just hoping someone had the same issue and I could cheat off of what they did to fix it lol.