Automotive Air Conditioning Information Forum

hey,
got a question. [ dont speak english very well, hope u understand]
in my car [Chrysler PT] should be approx. 510g r134a, earlier I found info on the internet (wrong) that it should be approx. 800g so I filled it up. At that time, I had about 6bar on LP and of course the air conditioning did not cool, hose before condenser was only slightly warm, I could easily catch it with my hand. So I pulled out refigerant, refilled with correctly 510g and now got an HP side of ~ 30bar. I think I was able to "overflood” the compressor before, when I had 6-7 bar on the pipe out of evaporator, something could happened to the oil in the compressor? it could have been flushed and moved further to the installation out of compressor?

or could be refrigerant contaminated with large amounts of air? dont have analyser

I doubt you have damaged anything.
BUT
30 bar is about 450 psi which is waaay too high and suggestive of air in your system.

After the overfill, you removed the refrigerant and installed the correct amount. QUESTION:
did you vacuum down the system for at least an hour with an electric vacuum pump before you installed the correct amount of refrigerant?

I actually worked on the PT at Chrysler, just carbon dated myself...

I don't think you damaged anything from what you've described. Vacuum correctly and charge correctly as tbird said, and you'll be OK.

You're doing fine with the language, so let's see whether we can help you.

What year is your PT Cruiser and how many miles (or kilometers) are on it?

Immediately, I noticed the pressures. If I'm doing the conversions correctly, 6-7 Bar (87-102 PSI) on the LP side and ~30 Bar (~435 PSI) on the HP side are much too high as previously mentioned. So I'm not surprised that the system is providing no cooling.

Where did you get the 510g (18 ounces) specification, from an under-hood decal, or elsewhere? By contrast, the specs that I have range from 24 ounces (680g) to 25 ounces (709g) of R-134a for USA-produced cars from model years 2001 to 2010. The oil specs range from 5.5 fluid ounces (163 ml) to 6.1 fluid ounces (180 ml) of PAG-46.

With those high pressures, your compressor is pumping fine.

tbirdtbird wrote: ↑Wed May 18, 2022 7:42 am did you vacuum down the system for at least an hour with an electric vacuum pump before you installed the correct amount of refrigerant?

yes, i pulled vacuum for max ~20 minuts, not more. Its not enough ye?

JohnHere wrote: ↑Wed May 18, 2022 7:48 am

Immediately, I noticed the pressures. If I'm doing the conversions correctly, 6-7 Bar (87-102 PSI) on the LP side and ~30 Bar (~435 PSI) on the HP side are much too high as previously mentioned.

Yes i know that is too much. If compressor is done i dont care so much, lets make a dissecting room. I would like to know what happens in inside a system that is overcharged in 170%.
- first i think txv is gutted because how else can there be such a high pressure on the evaporator? or it is possible ?
- superheat does not exist, evaporator flooded, i guess refrigerant include high% liquid coming back to compressor
- liquid refrigent could damage compressor ( eg distort valve plates?valve cover? u know what i mean... ) but..compressor is still pumping hard to up than 25 bar
- and now we have a feedback, how could be so high HP pressure when expansion valve could be open due to internal damage?

- first i think txv is gutted because how else can there be such a high pressure on the evaporator? or it is possible ?
I'm pretty sure all PT cruiser were orifice tube. Compressor capacity gets spoiled (reduced) as pressure ratio across it goes up, if it's orifice tube system it's running flooded back to the compressor, this spoils compressor volumetric suction pumping ability

- superheat does not exist, evaporator flooded, i guess refrigerant include high% liquid coming back to compressor
Correct, accumulator is completely full, liquid flooding back to compressor. If it's a TXV system, should still be superheated even if you are overcharged

- liquid refrigent could damage compressor ( eg distort valve plates?valve cover? u know what i mean... ) but..compressor is still pumping hard to up than 25 bar
Compressors are surprisingly durable, liquid slugging for long duration is part of compressor durability tests, your denso is a very good one, probably fine. You should not allow slugging, but for a short time, it's ok

- and now we have a feedback, how could be so high HP pressure when expansion valve could be open due to internal damage?
Your condenser is mostly full of liquid so very few available tubes that can condense liquid to get rid of the heat. If it is in fact a TXV in your PT, the high pressure is not it's fault, if it's orifice tube, same answer

CHARGE IT CORRECTLY, then you can start troubleshooting, or hopefully have a good running system and be done.

What year is your PT Cruiser and how many miles (kilometers) does it have on it?

The typical reasons both the low-side and high-side pressures are high are that the condenser (presuming it's not defective in and of itself) lacks sufficient airflow across it, that there's air and moisture in the system, that the system is overcharged, or that there's too much oil in the system. It's also possible that more than one of these problems exist.

Mentioned earlier was evacuating the system for only 20 minutes (at how many inches of mercury, at what elevation, etc.?), but not discussed was how the refrigerant was metered (weighed?) into the system or even which refrigerant was used. Are we talking about R-134a or an alternative refrigerant in countries in which R-134a isn't generally available? What was the ambient temperature when this work and testing were being done?