Only very small amounts of water dissolve in liquid R134a, but refrigerant vapour and water vapour mix freely — this page explains why moisture ingress is a serious concern for Volkswagen Golf Mk7 refrigerant circuit integrity.
| Only very small amounts of water are soluble in liquid
refrigerant. On the other hand, refrigerant vapour and water
vapour mix in any proportion. |
| Any water present in the refrigerant circuit will be carried
along as droplets. The dessicant, dessicant bag or dessicant
cartridge in the receiver or reservoir are capable of holding
approx. 7 grams of water before they are full and cannot absorb
any more water. If there is further water in the circuit, it
will flow to the expansion valve jet or to the restrictor and
becomes ice. |
| The air conditioning system will stop cooling. |
| Water destroys the air conditioner because at high pressures
and temperatures it combines with other impurities to form
acids. |
|
|
|
| Refrigerant is non-flammable. On the contrary, it has a
fire-inhibiting or fire-extinguishing effect. Refrigerant
decomposes when exposed to flames or incandescent surfaces. UV
light can also decompose refrigerants (UV is emitted by electric
arc welding). Products of this decomposition are poisonous and
must not be inhaled. However, these chemicals irritate the
mucous membranes, giving adequate warning of their presence. |
|
|
|
Questions & answers
Water content — Volkswagen Golf Mk7
Why is moisture dangerous in the Golf Mk7 AC system?
Water freezes at the expansion valve, blocking refrigerant flow. It also combines with R134a to form acids that corrode the circuit from inside.
In its pure state, refrigerant R134a is chemically stable
and does not attack iron or aluminium.
However, impurities such as chlorine compounds in th ...
There must be space both for liquid and vapour in a
container. As the temperature rises, the liquid expands. The
space occupied by the vapour becomes smaller. Eventua ...
