Not so cold A/C

That's a great list, keeping for future reference

Not to thread hijack but how often would it be recommended we have our A/C evacuated and recharged with proper amounts? Wondering if it's too early to bring a 2015 in to be serviced and have my high/low pressure valve cores replaced

 

50F out of the vents on a 70F day is awful.

 

@Taco'09 thank you very much for that list! I'll be shopping for prices today.

 

I would think that unless there is some damage to the condenser or something that on a '15 I would do.....nothing at this point. There is a guy on this forum who went 10 yrs. and very high miles before complaining about cooling inefficiency and then had it recharged.

BTW, there is a tool to replace the valve cores insitu. I have the tool and used it many times, kind of slick. Go out and unscrew the caps on both the high and low ports. It is very normal to get a psssssst from both. Notice the seals inside the OEM caps? They are there to minimize the escape of that pssssst.

Once in a while I just take the valve core tool and lightly twist them just to make sure they are snug. Don't go gorilla or anything as they will then begin to seriously leak. Just a tiny bit. The low side is a standard Schraeder core and the high an Acme.

 

R 134 pressures are ambient temp sensitive so 75* should yield low 35-40 psi high side 150-170 bottom line it's low, next question would be where did it go?

 

This seems like a valuable thread since my A/C was not so cold during 95 temps yesterday.

 

When looking at the manifold gauge as I understand, on the low side you should be looking at the lowest number when the compressor cycles on.

I assume this also goes for the high side (lowest number when the compressor cycles on)?

 

No... high side is your compressed vapor, going into the condenser where it condenses into liquid. Low side is the suction of the compressor, although it's still at pressure relative to the atmosphere.

With the compressor off, they should equalize, somewhere around 100psi. When the compressor kicks on the low side drops and the high side rises.

 

I'm probably not making myself clear.

When the compressor kicks on, the needle on the low side gauge drops, I know you're supposed to take the pressure reading when it becomes the lowest.

But for the high side when the compressor kicks on and the needle on the high side gauge rises, am I supposed to take the pressure reading when the pressure peaks? Or do I take the high side pressure reading at the same time when the low pressure becomes the lowest? I watched several of youtube videos and this was never made clear.

 

I mean... your high side should peak right around the time the low side bottoms out. It's a sealed system and the refrigerant that's getting pulled out of the low side should be going into the high side.

TBH I've never really paid attention to the high pressure as an absolute number, just relative to the low side and in trying to diagnose an issue... i.e. if the low side goes super low and the high spikes dangerously high, it's got a clog, if they're both high it's probably overcharged, if the low side stays relatively high and the high side stays low, the compressor isn't working right...

 

Oh ok. If the pressure swings look normal when the compressor kicks on and off, I'm going to shoot for 30 to 35psi on the low side at 75°F outside temp.

 

Got a quote for the o rings and what not using the list @Taco'09 posted...$160.00+. Next week i hope.

 

Yes! and no Leave the doors open if the system is cycling. You want it to run continuously. then read the gauges. The blower should be on high.

 

Thanks. I'm going to attempt it this weekend. I'm not going to evacuate the whole system. I'm just going to add a little bit at a time and check the pressures and temperature.

One Youtube video said if you keep adding refrigerant, the low and high side pressures should keep rising. Once the high side pressure stops rising and only the low side pressure is rising, that means too much refrigerant was added and you can release some after that. Is there any truth to his method?

Also what's the best way to clear the blue and red lines on the manifold gauge before adding refrigerant? There is a purge valve on the manifold for the yellow line but that does not help with the blue line. The blue line is pretty long so I imagine there would be a lot of air pushed into the system if I try to add refrigerant before purging it.

 

No. There are too many variables that affect pressures. You can just add freon, slowly, and get the system filled, but you have to know what you are doing. This isn't like airing up a tire.
Clearing air out of the lines, just hook up a can, burp a little thru each line, then connect the lines to the access valves.

 

Ok, just go slowly. When you think you are almost there, you probably are already there. I've overfilled before.
The best way on these newer systems that only hold 21oz, is to empty, pull vacuum, weigh in 21oz. Then if it isn't working right, you know there is another problem.
Edit: not working right means the gauge readings are off quite a bit.

 

I just recharged the AC with pure R134A (DuPont Chemours brand)

1. Ambient temp 70*F
2. After bleeding the air and hooking up the manifold gauges without turning on the truck, the low and hi side was 70 psi.
3. After turning on the truck and AC and letting it run for 10 minutes, the low side was 15psi and hi side was 100 psi.
4. I only bought one 12oz can of R134A. The system took all of it and the low side was 28 psi and hi side was 150 psi. I was shooting for 35 psi low side and 155 psi high side based on the ambient temperature. Should buy another can and add a little more?
5. Temepture was 42-44*F at the vents, depending if the compressor cycles on or off.
6. The compressor cycles on for 12 seconds and the cycles off for 12 seconds. Is this normal or should the compressor stay running on longer?
7. Even though I bought pure R134A, it left neon green residue on the hose fittings after disconnecting everhying. Is this UV leak detection dye or compressor oil?

 

Ooooook, so, I've ordered the pieces parts to replace the O rings and whatnot. As I'm changing my oil, I'm also scoping things out and notice the pipes coming through the firewall aren't parallel to each other. Is this normal?

 

Not necessarily, it there is very little humidity outside that and he is at a different altitude that may be just fine.