AC Diagnosis Help

2014 Tacoma AC stopped blowing cold.

Compressor clutch works, engages and disengages as it should.

Hooked up manifold gauges to test pressure.

**Edit - Updated test after fixing issue with high side coupler pin**
- Ambient temp 65°F
- Low side static pressure 38 psi with engine off, high side same.
- With AC running after engine warmed up, low side -1.5 psi, high side 70 psi.
- After engine shutoff, low side 47 psi, high side 46.5 psi.

Seems I have low refrigerant level and possibly a leak?

 

I bet your gauge coupler isn't pushing the valve down in the fitting or your gauge is dead, it's almost impossible for one side to be at 0 psi if there's refrigerant in the system.

 

Thanks for the help. I'll try another gauge set. The coupler on this one does seem to be properly seated.

 

You were right, there was an issue with the pin in the coupler. Got it fixed and now have the proper readings. Will update OP with findings.

 

Going by the pressures it's low, static pressure on a fully charged system should be about equal to ambient temp.
Running at that temp I would expect to see 25-35 on the low side and around 150 ish on the high side.
Dye added to the system and a UV light finds most leaks but sometimes they can be difficult to find even with a "sniffer" tool.

 

A leak and also a bad low pressure switch. The compressor should cut out at ~20 psi.

 

There's no low pressure cycling switch on 2nd gen trucks, the high side combination pressure switch will turn off if the static pressure drops below around 30 psi but it won't cycle the compressor on low pressure.

 

Dammit, I knew that. CRS on my end.

Am I half right, low on freon?

 

I’m working on diagnosing an ac issue. I think it’s the clutch plate as it just spins very freely with no resistance. I checked static pressure this morning with the truck off. It’s 85° here does this look right to you? Showing a fully charged unit?

 

No way to judge the charge by static measurement. If there is any liquid refrigerant at all in the system the high and low pressures will be what the table shows for the ambient temperature. And they will be equal.... which is what you have here. If you haven't had a leak it could still be OK. Just no way to tell from this.

 

ah okay. I thought static pressure being right in line with ambient temperature told you the charge was sufficient. I’m new to this so didn’t know.

 

Remember that we have a saturated system with liquid and vapor refrigerant present. As long as there is ANY liquid you will maintain this saturated system. So, the only time a static charge reading might be informative is if pressures were significantly lower than the table. That would mean that the charge is so low that all you have in the system is vapor, which means you have a leak. But you could still have a leak in your case, but it hasn't depleted the charge so much that the liquid is all gone. But no way to know. You need to check the pressures and vent temps with the system running with fan on high and airflow over the condenser. That will give you a lot better idea. The best way to get the charge exactly correct is to weigh in the exact amount specified on the under hood label into an empty system.

 

okay thanks for that tip. I’m going to replace the outter part of my AC clutch as I think it may be bad.

I have a question for you if you may know. The outter part of my ac clutch spins very very freely. Like almost zero resistance.

a friend of mine has a Tacoma and I tried to spin his by hand and it has quite a bit of resistance.

that led me to believe my clutch is bad. Would you agree?

I spun the part that is highlighted in green here with my hand

 

It should spin with not too much resistance. I don't understand what you are trying to do here. Is the system not working? If you turn it on the clutch should engage and drive the compressor. Is that not happening? Dash switch, relay, low pressure switch, clutch... that's the power sequence. So check that 12v power is reaching the clutch on that path.

 

mine I could probably spin a full revolution with 1 finger. His I definitely have to use my entire hand to spin. A toddler could spin mine it would take an adult to spin his if that makes any more sense.

my ac is not blowing cold. When I got the truck a few weeks ago it blew warm ambient air. We checked the refrigerant with gauges and it was low. We added 1 plain can of r134a about 10oz until the pressure was right and the vent temp was 40 degrees. My buddy did it for me he’s much more mechanically inclined than I am.

it worked great for 3 weeks no issues at all. Just 2 days ago when I drove it had perfect 40° vent temps with 90° outside temps.

my wife started the truck on Monday and it made a screetch noise when the AC was on and it was just hot air blowing.

when she starts the truck with the ac off and then presses the AC on button I can see the outter ring of the clutch spinning. However somsome said that the outter ring doesn’t matter what matters is that inner ring basically the face of the clutch.

someone recommended to try to spin it by hand to see if the compressor was locked up and said to feel another vehicles for reference so I tried my buddy’s Tacoma because I wasn’t at home to try mine.

when I came home I tried mine since I knew what his good working compressor felt like. Mine spins very very very easy compared to his.

that led me to think maybe the clutch is bad. Idk it’s just about the only thing I feel comfortable trying before I just take it to a shop.

I’m trying to learn a little at the same time.

I am nervous to go out and run my AC because I don’t want it to lock up if it hasn’t already. Maybe at this point if it is a compressor issue maybe just the compressor can be replaced and not everything else not sure how that works.

that is why I tested the static pressure. I know you said it doesn’t matter but I had read that if you check static pressure and it is the same as the ambient temperature than you more than likely have enough 134a in the system for it to operate. It was just a shot at checking making sure I wasn’t flat out of Freon.

here is a video of said screetch noise. I cannot replicate the noise now, and when she shut the fan mode off to 0 the noise stopped

https://imgur.com/a/5zckTzi

 

Again, if you turn the switch on, does the clutch lock and try to spin the compressor? That is easy to see and hear a good clack if you have the hood up and watch as she presses the A/C button. If it doesn't, then it is either any of those things in the power chain or the clutch. If the clutch does lock and the compressor doesn't spin, then the compressor is locked and needs to be replaced. That would cause the belt to screech and smoke if you let go too long.

Sounds like it's time for a shop.

 

not sure if you can tell from this video but when she presses the AC on button it spins. When she presses the AC off button it stops. All I can see is the outter ring not the center though.

https://imgur.com/a/9CjR5j5

 

I can't tell from here. Did you have the gauges on it when you ran it? If the compressor is turning you should see high side pressure rise and low side drop. Maybe the clutch is bad, maybe the compressor locked and made the clutch break (the screech?)? Is this compressor the original? If so, I'd recommend just replacing the compressor, comes with new clutch. There is little sense in doing a ton of work to replace just a clutch on a system that old because you'll just have to do it all again soon anyway. Likewise, if this had been previously replaced before with a reman compressor, get rid of it and get a new one. A brand new OEM one. Remans are junk.

 

im not 100% what the numbers read when he checked them with the gauges I’ll have to ask him.

I thought if it was just the outter clutch it’s like a 10 min job and I could try it if it works great if not no real time or money lost

I was really just trying to see if there was a way to tell if the compressor is locked up. I thought the fact that my clutch is spinning by hand especially so easily meant the compressor isn’t locked up.

I don’t mind to have the compressor replaced if I have to. However if it’s not locked up and didn’t contaminate the system with debris I would like to not replace the condenser if I didn’t have to.