Hi All, It is not really superb specific issue, so I am hopeful someone can help me. 

 

So I cannot comment on if the AC was working before or not.. I felt it was but you don't really know until you use it. Go to turn on the AC and I can hear a hissing sound (might just be the expansion). But it continues and I see no cooling effect.

 

Took it to a specialist (at closing time !) And he had a brief look round and initially he said probably just needs a refill because turning the AC engaged the compressor momentarily...

After which he decided to check using UV light (being told newer manufacturers put a dye in from factory ) From there he could see multiple spots on the condenser unit but weirdly enough there were lighter green dots generally on some pipes where you wouldn't have any leak paths (e.g. metal pipe).

 

In addition it looks like there is pressure in the AC system (5.2 bar). Now i cannot remember if this was on the high side or low side but the engine was off at this time and the guy was using a blue adaptor so I am assuming it was on the low side. So I have been told to run the system as is for 2 weeks and see if there is a pressure drop and then I will have to make a decision on what to do next, possibly replace the condenser. 

 

I have 2 questions.. Is there something else I can do to check and secondly to me 5.2 bar looks appropriate based on the pressure table in the service manual for R1235yf being 4.9 bar at 20 degrees c.  Can someone shed some more light on the issue please.

48 minutes ago, mfizz said:

From there he could see multiple spots on the condenser unit

Well, that makes me suspect a leaky condenser, but I can't be certain without knowing what pressure you're getting in test conditions. Your service manual table is meaningless unless the system is in the correct test condition when the pressure is measured.

Sorry bit of a novice what would be the test conditions?

 

Maybe I could be cheeky and ask him to evac and refill again just to see if it starts cooling again and evac again and sort the condenser out.

1 minute ago, mfizz said:

Sorry bit of a novice what would be the test conditions?

 

Maybe I could be cheeky and ask him to evac and refill again just to see if it starts cooling again and evac again and sort the condenser out.

You do know it’s not legal to fill a knowingly leaky ac system.

You really need to have a vacuum test done to see if system holds vacuum before filling with the correct weight of gas.

26 minutes ago, mfizz said:

Hi All, It is not really superb specific issue, so I am hopeful someone can help me. 

 

So I cannot comment on if the AC was working before or not.. I felt it was but you don't really know until you use it. Go to turn on the AC and I can hear a hissing sound (might just be the expansion). But it continues and I see no cooling effect.

 

Took it to a specialist (at closing time !) And he had a brief look round and initially he said probably just needs a refill because turning the AC engaged the compressor momentarily...

After which he decided to check using UV light (being told newer manufacturers put a dye in from factory ) From there he could see multiple spots on the condenser unit but weirdly enough there were lighter green dots generally on some pipes where you wouldn't have any leak paths (e.g. metal pipe).

 

In addition it looks like there is pressure in the AC system (5.2 bar). Now i cannot remember if this was on the high side or low side but the engine was off at this time and the guy was using a blue adaptor so I am assuming it was on the low side. So I have been told to run the system as is for 2 weeks and see if there is a pressure drop and then I will have to make a decision on what to do next, possibly replace the condenser. 

 

I have 2 questions.. Is there something else I can do to check and secondly to me 5.2 bar looks appropriate based on the pressure table in the service manual for R1235yf being 4.9 bar at 20 degrees c.  Can someone shed some more light on the issue please.

With the AC on check the temperature in the vent outlets which, depending on the ambient temps, should be around 8-12c. If the outlet temps are any higher then the gas charge might be low & it probably has a leak somewhere. Note that legally nobody should just add more refrigerant to any system without having 1st done a pressure & leak test on the system (environmental legislation punishable by substantial fines up to £200k under F-Gas regulations).

https://www.coolingpost.com/uk-news/200000-fines-f-gas-violations/

A nitrogen pressure test will find any leaks (luminous dye additives may help for small leaks). Any found leaks must then be repaired or parts replaced followed by pulling a vacuum on the system to dehydrate the system. A vacuum of at least 300microns or better still 500microns / 29.92Hg should be held (with the vac pump off) for at least 1hr, although most Auto AC tech's would only hold the vacuum for a few minutes before recharging the system. 

As such only a fully qualified Auto AC technician should carry out this work. 

I will be taking the car back in 3 weeks and he will check again the pressure remaining using the same process he used last time. If it drops, I must have a leak

I am aware of the legality of adding into the system without testing. Which is why I want to to do everything (legally) possible to diagnose the problem ensuring I don't have to return and do a refill of the r1234yf which will cost ~£100 / per go.

 

On a previous car, I had a vacuum test done and it held for the brief few minutes the mechanic did it for before refilling and 3 months later I was back at square 1.