Air Con: pre- works info gathering.

[davebb]

Hi to read the low pressure read with vida with out the compressor being on and before it has been on, you need to look at some charts on the webb that show the pressure vs temperature for the gas,
Dave

[ThomasG]

Right...

Without measurement suggested by davebb, - and so- awaiting confirmation

and with reference to this:

http://rechargeac.com/how-to/ac-system-pressure-chart

ambient temperature around 20-24deg Celcius

i should have readings of

compressor OFF - 241-310kPa (actual reading 880-900kPa)
compressor ON- 1034-1172kPa (actual reading 1100-1250kPa)

so...
"low" reading waaay too high
"high" reading nominal/on verge of "a bit too high"

first thing coming to my head would be "system overfilled/overcharged"

But..

I had it refilled some 2 or 3 years ago, for most of this time (that is- apart from last few months) it was working just fine.

I can see how there could be LESS refrigerant after some time after recharge, but MORE? How?

I for sure didn`t add any.

[ThomasG]

As per previous post- i have to assume that the normal pressure with system OFF- or in other words- low side should be within 1.7-3.2Bar (170-320kPa). information taken from general info in Vida.

In the same time website


http://rechargeac.com/how-to/ac-system-pressure-chart

tells me that in ambient temperature of 20-24degrees Ceslsius pressures should be:
Low side 241-310kPa
high side 1000-1172kPa

my readings taken few minutes ago:

after car being parked for nearly 3 hours, only ignition ON, not engine:

668.63kPa (i assume this to be LOW side reading)- fair bit too high

after starting the engine with A/C OFF (mind the system will start the compressor together with engine, for a system check, even if A/C is OFF good to know for those with failed bearings)

778.04kPa - High.. Too high

with engine running and A/C ON

1100kPa (+/-10, it fluctuates slightly, as expected)- I`sd say within norm


booking visit for A/C suckout and recharge for this afternoon

unless someone tells me otherwise before 4pm

[ThomasG]

170g of refrigerant recovered.

1000g recharged.

Its cold again.

Hopefully, its the end of this thread.

[rxtian]

Did you miss a zero on the amount recovered? I thought you had too much?

[ThomasG]

No o didn't miss a zero.

That was amount recovered, I wasn't told that by technician- I had my own eyes on the gauges and display of the machine.

Tech explained it to me as "part of refrigerant that wouldn't go into liquid state anymore".

Sounds a bit strange to me, I may do some digging into it at some stage, out of curiosity.

But the main bit is- it works again.

Will see for how long this time.

[cheshired5]

It's interesting how low gas can create a high pressure reading which I suppose is similar to an airlock in a cooling system.
My AC pressure reading is doing similar and struggles to keep up when it's very warm due to low gas I'm guessing.
It's been 4 years since my last regas though so it's overdue.

[JoeNinety]

@ ThomasG

For comparison purposes, what are "your" readings now you have had the work done?

[ThomasG]

That's a good one, JoeNinety.

I shall check that around midday tomorrow.

[ThomasG]

So.. for the record...

and I`ll just say that I`m a bit surprised myself:

with engine OFF, ignition ON (after 4 hours parked) 595.69kPa
engine ON, AC OFF, tickover- 790.2kPa
engine ON, AC ON, tickover- around 1170kPa
engine ON, AC ON, around 2100rpm- 1531kPa

and yet it works...