Automotive Air Conditioning Information Forum

Hello all, I just joined the forum to learn a bit more. Ive worked on cars for years, but never really messed with ac components. I’m at a loss with my current ac problem and hoping for some advise.

I have a 2012 Ford Focus. I just got the car, and the ac doesn’t work. The compressor won’t turn on. I checked the pressure with gauges, the low side is at 40, high side is at 50. So it seems the high side has low pressure. Although the low side is fine, the compressor doesn’t kick on. The fuses/relays checked out ok. I also replaced the compressor switch. I tested the compressor by jumping it, and it turns on with the jumper, but ac will not blow cold.

So it seems the high side pressure is low, and the compressor won’t kick on. When it is on (by jumper), ac doesn’t blow cold.

Can somebody help me with some advise on what to do next?

It is probably low on refrigerant. The best advice around here would be to vacuum the system down and recover the refrigerant and then add back in the proper amount by weight. I'd probably add in some UV dye to check for leaks and maybe add some compressor oil back in.

Rick

So although the low side pressures is good and the system won’t take refrigerant, it could still be low?

I agree with B52, but it might also be too cold outside, what was the ambient air temperature when you got those pressures?

It was about 72 degrees outside.

You are just low on charge, maybe a tiny leak. You should have about 72 psig at that temperature, your Focus ECM reads the ambient, reads the high side pressure, algorithm says you are so low on charge that there is only vapor in your system, it will not try to engage the clutch.

Recover what exists, leak check, evacuate, charge to the underhood sticker amount.

Dbwy wrote: ↑Thu Nov 25, 2021 7:31 pm Hello all, I just joined the forum to learn a bit more. Ive worked on cars for years, but never really messed with ac components. I’m at a loss with my current ac problem and hoping for some advise.

Welcome to the Forum.

Dbwy wrote: ↑Thu Nov 25, 2021 7:31 pm I have a 2012 Ford Focus. I just got the car, and the ac doesn’t work. The compressor won’t turn on. I checked the pressure with gauges, the low side is at 40, high side is at 50.

If those are static pressures, then the system is virtually empty of refrigerant, which is why the compressor won't run, as suggested earlier.

Dbwy wrote: ↑Thu Nov 25, 2021 7:31 pm I tested the compressor by jumping it, and it turns on with the jumper, but ac will not blow cold.

I agree with the suggestions posted above, and also stress: Don't electrically "jump" the compressor unless you want to replace it, along with the condenser. Doing so on a system having a low refrigerant charge or one that's nearly empty, as this one probably is, won't circulate the oil back to the compressor...starving it of lubrication, causing destruction of its internal parts, and sending the debris into the condenser and possibly beyond.

Dbwy wrote: ↑Fri Nov 26, 2021 7:41 am So although the low side pressures is good and the system won’t take refrigerant, it could still be low?

Static pressures don't tell us much other than that this system is nearly empty of refrigerant. By following the correct procedures already outlined and charging refrigerant gas from the low side into a well-held vacuum, the system will take the specified refrigerant amount unless there is some other problem.

The specs for this car call for 18 ounces net weight of R-134a and 4.1 fluid ounces of PAG-46. If the car has an under-hood decal showing different specs, the decal takes precedence.

Thank you so much for the advise.

I just vacuum pumped everything out. Let the vacuum run for about 15 minutes. Gauges were at 0, and low side gauge was at -10 under vacuum (I’m assuming that meant the vacuum was working). After that, I added Freon and the system only took about 6 ounces before it wouldn’t take anymore. I then jumped the compressor to see if it would take more, but it wouldn’t. Low side gauge was reading 45, high side gauge was reading 35. I feel like an idiot. Does this mean there’s a clog somewhere? Maybe I didn’t vacuum it long enough? But after the vacuum both gauges were at 0.

I’m reading up about static pressures. I’d like to add that the low side pressure didn’t change when I jumped the compressor.

Ok so the Freon can was freezing up and it took like 30 minutes to get the car to take Freon.

You guys were right, it’s working great now! Thank you so much for the help!