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Common Issues with Ammonia or 3 Way Fridges

Ammonia Fridges, also known as Absorption or 3 Way Fridges, work using technology dating back to the 1850's. The refrigerant used in these fridges has a high boiling point and therefore requires high temperatures to evaporate, and rely either on a gas flame or an electric heating element to create that heat. To generate such high temperatures, a lot of energy is required and heat produced then needs to be removed and isolated from the cold inside parts of the fridge. In this article we list some of the common questions asked regarding Absorption or Ammonia Fridges.

Why does my fridge sometimes gets cold and other times not, for no apparent reason?
  • At the beginning of this article we mentioned that Ammonia or 3 Way Fridges rely on heat for cooling, but they are also dependent on gravity. As the fridge has no pump to force the refrigerant round, it will not work properly if the vehicle is not parked on flat ground. Newer Ammonia Fridges suffer less from this problem as the design angle of the refrigerant flow has been increased.
  • On a hot summers day, if the fridge side of the vehicle is in full sunshine, it might get so hot that the fridge can no longer get rid of the excess heat building up. This can cause the inside of the fridge to defrost but once the sun goes down the fridge should start working again.
Why does my fridge work on gas but not on 240 volt?
  • If the fridge works on gas but not on 240 volt, then the 240 volt heating element may be burnt out. To check this, first look at the 240 volt circuit breakers to see if they have tripped out.
  • If the element is burnt out it can be replaced, but in most cases the fridge must be removed to do so.
Why is the fridge so hard to ignite?
This is a common problem and can be due to: a nearly empty gas bottle at low temperatures. In other words the temp has dropped so low that the butane gas in the bottle will not evaporate into liquid gas. Replace with a full bottle that has the correct mix of Propane to Butane levels, as the Propane evaporates better at cold temperatures than Butane does.
  • The flue is dirty so the fumes cannot pass through the flue efficiently. This mostly happens after the vehicle has been in storage for a while. Insects can make the flue their home, causing in-correct gas to air ratio mixtures.
  • The burner is dirty, this is mostly caused by rusty flakes from the flue stack that land on the burner.
  • The capacitor to the igniter is blown. If you cannot hear a clicking noise, which creates the spark when you turn the fridge onto "GAS", or with an old fridge when you manually push the ignition button, and there is no visible signs of a spark through the looking glass, then a component of the igniter is faulty and you should seek advice.
  • The gas lights but will not stay on: the fail safe device on the burner is faulty, or is not set correctly, the fridge needs servicing.
Should I be worried that I can smell fumes inside my motorhome?
  • This should not happen under any circumstances. Please do not use the fridge at all, until it has been serviced.
  • If the fumes smell of LPG then you are in danger of a potential fire or explosion.
  • If the fumes smell similar to exhaust gasses from a car, then you are in danger of carbon monoxide poisoning, also known as the silent killer. Sleeping in such an environment is very dangerous.
Why wont my fridge work off the batteries?
  • The 3 Way Fridge should never work on the battery if the engine is not running. Most vehicles are wired in such a way that the fridge will not operate on 12 or 24 volt if the engine is turned off. This is because the energy consumption at 12 volt on a 3 Way Fridge is so high that it will only work when the engine alternator is generating enough power to operate the 12 volt heating element at the back of the fridge. The 12 volt element could be blown, or the wiring to the 12 volt part may be faulty. Complete removal of the fridge is usually required to repair this fault.
  • If the fridge does not work even when the engine is running then a fuse may be blown, or the 12 volt heating element is blown. The element can be replaced but mostly the fridge must be removed