Low Side Gradually Decreases

[UNiT555]

Hi Team!!
First Post for a GreenHorn!!!

Im from Australia working on my 2012 Ford Fiesta 1.6 vct petrol and am having an issue with my low side starting off with correct pressures (around 15 - 25 psi ((i’m running a lpg based refrigerant called HyChill hence the lower pressure)). All is well and the A/C is bloody cold.

The AC cycles on and off which is cool.

But as the A/C stays on, the compressor stops cycling and stays on and the low pressure side gradually decreases almost going into vacuum and by then the air is not as cold.

Here’s where the greenhorn “shooting the parts canon” comes into play. I’ve replaced the condenser and tx valve to no available. The compressor was also changed albeit a second hand one from the wrecker.

High side pressure stays normal around the 150 mark.

Pressures normalise to around 100psi when engine off….

Any clues my friends?

Thsnk you very much in advance!!!

Regards
GI-Joseph

[tbirdtbird]

Pictures of your low and high gauges would help.
Do you have a source that gives the total refrigerant charge needed for the car?
Was any work done on the system?
I am nearly ready to suggest that you have the system reclaimed, evacuated, compare the amount of refrigerant reclaimed to the book value published by the mfg, check for leaks (there are several ways to do this), then recharge to correct charge, and get back to us

[Tim]

This is a US-based forum. Not many of us work with HC refrigerants, and many posts over the years have always had charging issues with HCs.

[JohnHere]

I don't know much about HyChill because I don't use alternative refrigerants, but I believe that it contains mostly propane, which IMHO should be used only as a fuel gas. I'm surprised that the US-EPA equivalent in Australia allows charging a highly flammable substance into MVAC systems.

Is not R-134a available in Australia, if not to the general public then at least to professional A/C shops?

[Cusser]

Is not R-134a available in Australia, if not to the general public then at least to professional A/C shops?

I did a search, and in Australia R134a is not available to the general public, only to mechanics with a special license.

[JohnHere]

Much obliged, Cusser.

That explains the presumed popularity of such alternative refrigerants as HyChill in Australia.

[Tim]

As I mentioned, these HC's always seem to have pressure issues, at least the ones that come here. I'd like to help with the poster, but I just don't work with it or know the tricks to make it work. Websites, in general, say they charge it and forget it.

[UNiT555]

Thank you for the replies gentlemen!!!
Im actually quite glad that ya’ll are finding my post interesting!
By the way, for those who are “worried” about charging a fully sealed system with 200g of HC’s, dont be, have you seen what those electric vehicles are doing with their spontaneously combusting behaviours as of late?
Hope you can detect my exegaration there and also hope you can detect my common sense gauge in this post! I may not be 100% fluent in my a/c skills but safety is my priority and quality is also paramount, so doing things the proper way is of high importance to me.
HyChill have a website that answers all your concerns.

[UNiT555]

Pictures of your low and high gauges would help.
Do you have a source that gives the total refrigerant charge needed for the car?
Was any work done on the system?
I am nearly ready to suggest that you have the system reclaimed, evacuated, compare the amount of refrigerant reclaimed to the book value published by the mfg, check for leaks (there are several ways to do this), then recharge to correct charge, and get back to us

Thank you my man!
Yes i have done all of the above.
I think i may have a tiny leak on the low side shraeder valve with which ill replace.
Ive done a 250 micron pull on the system.
Flushed evap core and installed new tx valve and condenser.
New second hand compressor was also installed.
System works, ac is colder than antarctica, pressures start off beautiful, around 25 psi on the low side as per hychills data. But then slowly, the low pressure side drops lower and lower and lower. Hychill suggests that its a stuck tx valve and ive been told that my evap core is not getting enough air over it and its freezing the tx valve.
The blower fan blows nice and hard although i did have a plastic piece that directs air that i havent put back in which fell off and i simply thought its not needed. Surely that cant be the culprit. Anywys, if i turn the car off for 5 minutes and turn it back on, the low side pressure is normal according to hychill but then slowly decreases…
Which is idicative of a stuck tx valve….
So hence my question here to see if there was some more lighting to be shed i suppose
Very much thank u for the interest in my post and greetings to ya’ll from ac dc land.

Gi joseph

[UNiT555]

Pictures of your low and high gauges would help.
Do you have a source that gives the total refrigerant charge needed for the car?
Was any work done on the system?
I am nearly ready to suggest that you have the system reclaimed, evacuated, compare the amount of refrigerant reclaimed to the book value published by the mfg, check for leaks (there are several ways to do this), then recharge to correct charge, and get back to us

I will get pics!!!
Please be patient with me.
Alot on plate!!