Home aircon testing

[rcx132]

I'm new to air con, never touched it before, this is my first time. I've got a leak, it's a worthless car so thought I'd try to find the leak myself. My brother filled the aircon system for me with Nitrogen, 80psi and put in some UV dye. That was three weeks ago, the pressure is now at 10 psi.

I've only just had a chance to put the car into a dark garage to look for the leak with a UV torch. There's nothing I can see, so the leak must be behind the dash right? There's also a HVAC thingy at the rear of the car, apparently for the rear heating (it's a people carrier). So the leak could be there.

Just thinking though, do I need to switch on the air con to distribute the dye? Since I've had the car the VAG-COM says there is an aircon error due to low pressure, so I assume I need to repressurise the system back to 80 psi and clear the VAG Com error for the pump to switch on?

 

[doubleboost]

I'm new to air con, never touched it before, this is my first time. I've got a leak, it's a worthless car so thought I'd try to find the leak myself. My brother filled the aircon system for me with Nitrogen, 80psi and put in some UV dye. That was three weeks ago, the pressure is now at 10 psi.

I've only just had a chance to put the car into a dark garage to look for the leak with a UV torch. There's nothing I can see, so the leak must be behind the dash right? There's also a HVAC thingy at the rear of the car, apparently for the rear heating (it's a people carrier). So the leak could be there.

Just thinking though, do I need to switch on the air con to distribute the dye? Since I've had the car the VAG-COM says there is an aircon error due to low pressure, so I assume I need to repressurise the system back to 80 psi and clear the VAG Com error for the pump to switch on?

You should never run the ac charged with nitrogen
The ac gas is put in in liquid form with the dye and a lubricant
We do a pressure test to 150 psi nitrogen

 

[rcx132]

You should never run the ac charged with nitrogen
The ac gas is put in in liquid form with the dye and a lubricant
We do a pressure test to 150 psi nitrogen

So what does the nitrogen get used for? Just to check if theres a leak? But to find where the leak is it can't be used?

 

[doubleboost]

it is just used as a pressure test medium you dont run the system with the gas in it

 

[ukracer]

it is just used as a pressure test medium you dont run the system with the gas in it

Why not just use air john?

 

[Seadog]

Oxygen = corrosion so you use an inert gas.

 

[colnerov]

Hi, The system work by the refrigerant changing state from liquid to gas and back to liquid and so on. The process for checking and charging the system is to evacuate it down and then leave it to make sure it holds a vacumm, then pressurise with OFN (Oxygen free Nitrogen) to check it will hold the pressure. Then the OFN is removed and the refrigerant is charged in with the lubricant and dye if needed. The most common places for leaks is the condenser (in front of the main radiator) due to impact damage from stones or other debris, or the front seal on the compressor. Tell tale signs are a dirty damp area, leaked oil covered in dust, or use of an ultraviolet light if there's dye in it. Putting refrigerant into a leaky system is very naughty and can result in big fines.

Colin

 

[rcx132]

Hi, The system work by the refrigerant changing state from liquid to gas and back to liquid and so on. The process for checking and charging the system is to evacuate it down and then leave it to make sure it holds a vacumm, then pressurise with OFN (Oxygen free Nitrogen) to check it will hold the pressure. Then the OFN is removed and the refrigerant is charged in with the lubricant and dye if needed. The most common places for leaks is the condenser (in front of the main radiator) due to impact damage from stones or other debris, or the front seal on the compressor. Tell tale signs are a dirty damp area, leaked oil covered in dust, or use of an ultraviolet light if there's dye in it. Putting refrigerant into a leaky system is very naughty and can result in big fines.

Colin

But you're saying that the dye goes in with the refrigerant to find the leak but you can't put refrigerant into a system that leaks. So isn't that catch 22?

I'll check the two places you say usually leak.

 

[Seadog]

I think what is being said is that when the system is refilled they put a dye in to aid future fault finding. At least that's what I remember from a conversation with the engineer that looked at my Range Rover many years ago.

 

[Rig Pig]

The few times I have messed around with ACs the leaks have been easy enough to hear when there's pressure in the system.
Check the receiver/dryer, that's where my Passat leaked.

 

[Kayos]

A garage near where I used to live had a cheap aircon refill deal, took one look at the freelander and said it will be extra before they even started

I risked it and bought a kit from Halfords and had icy cold aircon, how can they sell the kits if it’s illegal to release the gas? There could have been a big hole in something (I knew it just needed gassing but they didn’t)

 

[rcx132]

A garage near where I used to live had a cheap aircon refill deal, took one look at the freelander and said it will be extra before they even started

I risked it and bought a kit from Halfords and had icy cold aircon, how can they sell the kits if it’s illegal to release the gas? There could have been a big hole in something (I knew it just needed gassing but they didn’t)

Different laws work differently. Sometimes the law makes items illegal to sell, but not buy (e.g. bull bars), other times you can buy something but it's the buyers responsibility to use it legally, e.g. air con kits.