oilcanhenry

Yes, it would be a good idea to put a good set of gauges on your A/C system. Ideally, on your unit you want 30-35 PSI on the low-side and 170-225 PSI on the high-side, depending on the outside temperatures. The higher the outside temps are, the higher your readings will be. 184K isn't too high. I was thinking it might be even higher
but for a 22-year-old Chevy 184K is quite a normal amount of milage at 8000-9000 miles per year average mileage. Pickups used for work, often have more lots more milage then that on them. Your static pressure (engine off) should be 70-75 PSI at 70 F degrees.

They do sell R-134A with leak detector added to it, as I suspect you likely have a leak, but if the system still has pressure, that's a good thing as you don't want any air in the system at all and the leak detector will not cause any issues to surface The parts stores also sell a product that claims to seal up the A/C system but I would advise against using that for two reasons. It often doesn't work, and it can really cause more problems. There are some real horror stories about people that have added that product to their A/C systems. Unlike Alumiseal or Bar's Leak, for a small radiator or heater coolant leak, which I have had good results with, the A/C sealant is nothing like that at all. If you do decide to add one can of R-134A to your Chevy, you might want to buy a can with a 1 oz charge of PAG 150 A/C compressor lubricant, which is what your vehicle uses. PAG oil is what all R-134A systems use, but like motor oil they come in different weights, such as PAG 46, but your system uses PAG 150 oil.

Edit: I think I may have found out why your A/C system is not cycling as mine, and your father's 1998 Chevy pickup, does. There is a switch mounted on the accumulator or what we used to call a receiver/drier, called an "A/C clutch cycle switch", I've worked on lots of A/C systems and never seen a bad one, but as I said, I am not a professional mechanic, who likely has seen this occur, although I've worked on many auto A/C systems. The device is under $20 to 30 dollars depending on the brand, and if what I read correctly is true, there is a Schrader Valve (like on your car tires) on the Accumulator, so you won't have to recycle the R-134A A/C refrigerant in your system, the valve will keep the R-134A from blowing out when it is replaced, so no discharging the A/C system is needed.

It's located right next to your low-pressure hose going to the A/C compressor and has an electrical connector that is controlled by your ECM, so that the evaporator in your can does not become too cold and freeze up, as tech2 said. I have uploaded a picture of my own A/C clutch cycling switch so that you can see it clearly. Its the switch with the green and black/white wires going into the accumulator, between the low-pressure hose going to the A/C compressor and the Mass Air Flow (MAF) sensor which goes to your throttle body unit for air delivery to your engine from the air cleaner. Make sure if yours is the proper one, as I believe they come in two styles. You'll find this link by one of Chevrolet Forums' sponsors, CARiD, to be helpful. I have no association with them, but since they are one of C-F's sponsors, it's a real good company.

https://www.carid.com/1998-chevy-ck-...885253282.html

Mr. Dude with a face

@oilcanhenry Thank you for all of the information, you have really gone above and beyond! So, if I am understanding you correctly, a probable reason for my sub par A/C could be low refrigerant caused by a small leak. And it could also be the cause for the compressor not cycling? And you are also saying that if it is not the level of refrigerant it could be the switch? (Thank you for the picture) Thinking about it that switch does make sense, I don't know much but I do know that freezing the evaporator is an issue.

Also, I saw you mentioned static pressure. I have never heard of it before, and the pressure you list, is that for the high pressure side, the low pressure side, or both?

oilcanhenry

You are quite welcome, Mr. Dude with a face. I hope that I can help you solve your A/C issue as it is no fun at all driving in hot weather at all. I know, as many years ago most commercial vehicles did not have A/C, as they do now, and all we had was an electric fan on the dash and all the windows rolled down. Not much fun at all, trust me.

My Chevrolet pickup (and my 2015 Chevy Malibu) put out no less than 42 F degrees F at 90 to 100 degrees Fahrenheit in outside temperatures, according to my thermometers in the center dash outlets of both vehicles. Had I had it to do my life over again, I would have become a full-fledged mechanic/tech, but I do love to drive.

Static A/C pressure is when the engine is turned off, so the A/C system is not running, and the high and low sides are equalized in pressure. When the motor is running or with the A/C turned on, the A/C compressor is then running to cool your vehicle down by changing liquid R-134A to a gaseous state, which is how all A/C systems work to absorb heat, The refrigerant must be under pressure to remain in a liquid state so that when it reaches your evaporator, it changes into a gas, which absorbs heat and the fan blows the cool air into the passenger compartment. It also dehumidifies the cabin, which is why when you park the vehicle, there is a puddle of water under the vehicle.

It then returns to the compressor where it's pumped into the condenser mounted in front of your vehicle's engine coolant radiator to be condensed back into a liquid state. The engine fan or fans when the vehicle is stopped pulls air over the condenser and the engine radiator to keep both systems cool, but as you drive the outside air does a better job of cooling the refrigerant down to a liquid then the fan can in many cases. That's why your vehicle A/C will often cool down much better while you are driving

Even in your home refrigerator/freezer, or your home air-conditioning system, although they don't use R-134A as a refrigerant, the principle is still the same. Converting a liquid to a gaseous state absorbs heat Static pressure is simply another way to diagnose any problems with an A/C system, but many people don't seem to know about it. If your A/C system in less then 70-75 PSI in static mode, as my own 1998 Chevy K-1500 pickup is at when not running, then you are indeed low on refrigerant and proper pressures, or there is something else amiss with it. I hope that the issue you have with your Chevrolet can be solved with a new sensor, but if not I will still be here to help.

Mr. Dude with a face

@oilcanhenry So, what I am thinking is I will check the charge in my system, and if it is good, should I then replace that switch? I am reluctant because I would assume that switch being broken couldn't cause the A/C to function poorly, in fact I would imagine it would actually make it work too good, freezing the evaporator and me at the same time. Is that about right?

oilcanhenry

Yes, it is. You don't want the evaporator freezing up at all, which is why all A/C systems have a way to keep that from occurring, as with the compressor cycling switch on your Chevy pickup. In the case of your 1998 Chevy, the compressor cycles to keep the evaporator from becoming too cold and freezing up, but with your outlet temp in the cab at 60F that won't occur as your evaporator cannot function properly without enough R-134A, so that's likely why it does not cycle, as the evaporator is not cold enough.

The last thing you want to do is damage the evaporator, as installing a new one means ripping the dash apart and removing the climate control box, which is a real chore, trust me on that. At this point in time I'd put a good set of A/C gauges on your Chevy to read both high and low side pressures. If it is low, then you can add a can of R-134A and if it cools down okay, but later on, it does not, then you have a leak somewhere in your system. I think it's possible that the reason your system is not cycling is that it is low on refrigerant, so replacing the compressor cycling switch won't be necessary unless, at the normal pressures high and low pressures, your compressor is still not cycling, which it is supposed to do, when the A/C system is operating normally. BTW, if you see any "oil" leaks anywhere, it could be the PAG A/C oil leaking out, Check all your A/C lines and the compressor for this matter.

When you add a can of R-134A to your low-side connector, allow a bit of it to escape, before cinching it down tight. This will insure that you are not allowing any air into the A/C system. It's a common mistake made by many people, even professionals, to not flush the air out of the lines, before adding the refrigerant into the air-conditioning system. The less air, the better your A/C system will operate and the less moisture there will be that the receiver-dryer-accumulator will have to absorb with its moisture desiccant.

Mr. Dude with a face

Ok, and update. Today I put the gauge on it again, now mind this was just on the low side, and it is a cheap gauge, but when I put it on it showed that the system was very over charged. The person I was working with quickly determined that it was over charged. Now I know this isn't what you are supposed to do, but he did let the excess refrigerant out of the system. I didn't like it but by the time I was going to say something, we where already kind of committed. Environmental stuff aside though, after letting out an absurd amount of refrigerant, we got and easy 10-15 degrees out of it. Now, we will see in the coming days, but today was 95 in Utah, we where in the shade for most of our work so we will say about 85 in the garage. We even went as far as to pull the truck outside and spray water through the condenser and that provided and extra 5 degrees. The coldest I saw today was a little over 45 degrees. After this we felt pretty good we had made progress so we let the truck sit for a while out in the sun as we did other things. On the way home I got on the freeway, going about 65 MPH and from what my gauge says (not the most acurate, and hard to read) I was getting about 50 degrees. I will include some pictures so y'all can see what I am talking about.

Just not cutting it, sitting idling, 70 degrees (this is the gauge I trust)

Pressure is too high, green means under charged, yellow means over charged and blue is just right. I looked at the static pressure, it think it was well over 100.

Starting to make some progress. This is after letting some refrigerant out (I know, not the right thing to do) If you cant see it reads about 50. We adjusted this one so it is pretty close to the big one, I think it was of by 5 or more degrees.

oilcanhenry

Well, 50 degrees A/C output in 85 F outside temperatures is not good enough. Too much R-134A can actually reduce the efficiency of the A/C system. It's really becoming difficult to diagnose your A/C system, as you don't have any high-pressure readings for me to see. Might be someone in your location that will check it for a modest fee, as I do where I live.

Is your compressor cycling at all since the excess R-134A was bled out to the atmosphere? (hey, things happen so no blame here as R-134A was supposed to be an eco-friendly, safer alternative to the old R-12 "Freon", but now many auto companies are switching to a slightly flammable A/C refrigerant called R-1234yf in the new vehicles)

If not, I suspect the culprit as the compressor going south, even at your mileage. Stuff happens, but I really think that you need to get a high and low A/C pressure reading on your 1998 Chevy.pickup so I can advise you further on what you must do to get your A/C down to 45 degrees F or less, as it should be, and as tech2 explained to you. It's 100 degrees here and my Chevy is blowing out at a nice cool 42 degrees F, for instance. Your A/C unit should be doing the same, but until I can get more information, I cannot help you.

Mr. Dude with a face

@oilcanhenry Yes, I totaly agree. The stuff I did yesterday was out of the fact I had the opportunity, and I did make progress, I do think that I will get a real test done on it, I have already been sourcing a friend who has a set. Also, how much does outside temperature effect the pressures? I have been trying to include temps for that reason.

tech2

after every shop put out $6000 for new 1234yf ac machines(yf=yourf'ed if you have this refrigerant) the industry decided if was no better and went back to r134a.

yf at $1000 per 10lb tank, much more difficult to find leaks compared to r134a and much slower to fill due to the new machines doing leak testing procedures for every fill..it was a fail.

oilcanhenry

Yeah, getting high and low readings will help Dx your A/C issue.

It's in Celsius, but still works if you convert to Fahrenheit.

https://www.agas.com/media/2404/r134a-pt-chart.pdf