To be honest, if you keep having trouble with it and insist on doing it yourself, the best thing you can do for the long run, is disconnect everything in your system. This is especially good if your system has not been serviced and/or not running for many years. Remove the orifice tube and replace it. Replace all of the o-rings with new ones, and ensure your valves are new and working. You need to flush your evaporator out, as well as the condenser to ensure no blockages, removing contaminants, (plus any other hose). You should replace the accumulator completely with the new pressure switch installed, but do this last as you don't want it sitting open absorbing moisture. If your compressor is confirmed to be working, make sure no crud is in it. You will need to add appropriate oil into the system. Once it's all connected you can go ahead and vacuum all the air out again. After that add in your refrigerant slowly, while monitoring vent temperatures and monitor high side if you can. Keep in mind what your max capacity is so you don't overfill.

 

So the "valve" you are referring to right here now, is the Pressure Relief Valve? {It would help if you would call parts by their proper name when you learn them, as it reduces confusion greatly}

I would think that your new HPCO, as seen in the doc that RLA2005 has nicely provided, opening at ~445 PSI, would have shut down the compressor before the high-side pressure could have gotten up to well over 500 PSI to blow the PRV open. So maybe the PRV is opening at waaay too low of pressure.
I believe the only way to get a new PRV is with a new hose manifold assembly, but I could be wrong. If it IS replaceable, its probably on there real good, wouldn't want to break the manifold or open up the manifold to compressor O-rings.

If I was troubleshooting this, I would have the engine warmed up so the idle speed has dropped to the lowest possible, gauge set hooked up. Somewhere convenient I would break into the feed to the clutch, maybe pulling the connector off of the CPS, so I could extend the harness end out with some wire out to where I could remotely close/open the clutch circuit while watching the gauges.

Then I could close it just for an instant and watch the gauges. Then again, making it ON a little longer, work it up longer like that a little bit longer ON at a time. Want to see what the high side builds to and does vs. low side vs. any venting of refrigerant. If high side looks reasonable for the conditions, low side too, and then it starts to vent on its own, then its a bad PRV.

If the high side instead goes sky high, and low side is just about zero, or negative into vacuum, then there is a major restriction.

Doing it this way would slow it all down, so things could be seen, sort of in slow-motion, instead of just a big bang - its over.

The maximum restricted head pressure a reciprocating compressor can reach is a function of its piston sealing, reed valve sealing, and input shaft RPM. A compressor in good shape can easily exceed 500 PSI. It ain't good for it to do it very long, as the loads on the piston shoes on the swash plate are brutal. The Denso designs are pretty stout as far as the heads and main cylinder body strength.

 

134a turns into liquid at below 200 psi pressure as shown here:



So how can you create 500 psi pressure unless you try to compress liquid (water, oil, or liquid Freon)? And compressing liquid will damage your compressor!

 

NO. You misunderstood the diagram you linked, and then used the Example that had specific operating condition numbers on it, as if it were a Rule.

I'm not going to teach the refrigeration cycle here. However, I took a look at Wiki to see what they had. At this link:
https://en.wikipedia.org/wiki/Heat_p...geration_cycle
Look at Vapor-Compression Cycle. Figure 1 is the system.
Figure 2 is a simple well-described diagram. It is an ideal diagram, it does not show real-world design of degrees of superheat at compressor suction port, nor does it show degrees of subcooling at the entrance of the expansion device. Nonetheless, it is a good diagram. The Y-intercept constant pressure values that are on or within the curve can be slid up and down the curve both in design and certainly will move in operation!!!

I also linked a R-134a P-T Chart here: Pressure - Temperature Chart for HFC-134a
They decided to stop their chart at 380 PSI. But it continues on.

And linked a simple Automotive P-T chart with service port gauge pressures here: http://www.mastercool.com/wp-content...89660-INST.pdf
The "Ambient Temp" is the temperature of the air that is flowing through the condenser. In reality, the condenser is in an environment that is hotter than the outside ambient, as the condenser is being back-heated via both convection and radiation by the hot engine radiator. So for example, 100F on the chart may be occurring with a 95F outside temperature.

 

You used the wrong chart, should be saturated pressure-temperature:



So what temperature you think you can survive? You plan to drive your car into molten metal? :-)

 

The P-T chart I quickly linked IS a SATURATED P-T chart. What good would it be otherwise? Doing a spot-check comparison at various temperatures between the chart I linked and the one you posted are at most a couple pounds different. That's a don't-care level of difference when looking at a discharge gauge.

I don't plan on having to survive high temperatures, however, I'm real glad that my compressors, discharge tubing, discharge hoses, and condensers can survive it. Same for residential/commercial/institutional A/C and coolers/freezers.

But, you don't have to believe any of this, it's all lies anyway.

You could run a "Bacon" test. "Everythings better with bacon".
The hotter the ambient temp, and the higher the humidity, the better. Start up vehicle with manifold gauge set attached. Open doors and windows and have cabin fan on High. A/C ON. Let it run for a few minutes, then by hand grab and hold on tight to the discharge tubing right at the compressor output. Look at the discharge pressure gauge, note the reading, then across the bar on the dial face to the corresponding temperature for said refrigerant at that pressure. Any bacon yet? No? Hold on longer.

Repeat Bacon test with cardboard blocking the condenser's front, right at the condenser's face, not in front of the grill. Repeat holding on, and watching discharge gauge pressure/temp. Bacon yet? No?

 

The temperature here is not the survival temperature of your components, but rather that of the refrigerant after the condenser...
There is no lie in science; only lying scientists. :-)

 

So I got my ac working. Now I have another question. Does the high pressure port have a valve stem inside it? It appears to just be a little ball like thing but the kit came with high and low valve with two stems. I didn't see how the valve stem would go into it so I put it on as is. Now I have pressure coming out the valve after charging up. No refrigerant comes out thohgh it's just like air. And it's slow but enough for the cap to not stay on.

 

How can you ac be working when you don't even have a tight system? It still leaks, doesn't it?

 

It was working until it lost the freon. It was a slow leak. Couldn't even hear it. It just ended up being that the high pressure port valve autozone sells is junk.

So for anybody that refers to this thread in the future here's what the deal was.

The high pressure switch on the back of the compressor was bad. Replaced it and the compressor turned on and the clutch engaged. Then I replaced the valve on the high pressure hose four times (don't use autozone.) I replaced the accumulator and about $200 later I have nice cold a/c in my truck. A week of workin at it here and there and I learned some stuff and spent less than a shop would charge.

 

In AC world, when you hear a leak, that's not called leak anymore: that's flooding! :-)

You need a REFRIGERANT LEAK DETECTOR, such as this cps LS790B which can detect a leak rate of better than 0.25 oz/yr (7g/yr) of HFC. Your regular 134a can holds about 12 oz, which means this detector can detect a leak on the can that takes 48 years to empty it! That is called leak.