Odd freeze switch failure
05-16-2010, 05:54 PM
#1
Drifting
Thread Starter
Odd freeze switch failure
Just back in from garage having replaced the aircon freeze switch (928.613.133.00).
Very peculiar failure. The freeze switch is normally a short circuit, unless the aircon evaporator freezes over in which case it goes open circuit and cuts power to the compressor clutch.
In my case the switch showed a resistance of around 600 ohm (measured across the terminals, with connectors removed) instead of what should have been a short. It had done this a few weeks back (the compressor clutch wouldn't engage) and as a temporary fix I found bending the terminals restored continuity. Obviously it was a very temporary fix as problem returned next trip!
It's a weird part with a capillary tube containing fluid which pushes through a deep hole to reach the evaporator. Inside it resembles a mousetrap with a very powerful spring which trips the circuit when the probe freezes (in past have had fun playing with this switch and glass of iced water).
Cheap to replace from OPC though - about $35.
So if your aircon compressor stops turning, this is a possible cause to check. Presumably some kind of corrosion/gunk on the terminals caused the high resistance?
Just need some warm weather in the UK now!
Very peculiar failure. The freeze switch is normally a short circuit, unless the aircon evaporator freezes over in which case it goes open circuit and cuts power to the compressor clutch.
In my case the switch showed a resistance of around 600 ohm (measured across the terminals, with connectors removed) instead of what should have been a short. It had done this a few weeks back (the compressor clutch wouldn't engage) and as a temporary fix I found bending the terminals restored continuity. Obviously it was a very temporary fix as problem returned next trip!
It's a weird part with a capillary tube containing fluid which pushes through a deep hole to reach the evaporator. Inside it resembles a mousetrap with a very powerful spring which trips the circuit when the probe freezes (in past have had fun playing with this switch and glass of iced water).
Cheap to replace from OPC though - about $35.
So if your aircon compressor stops turning, this is a possible cause to check. Presumably some kind of corrosion/gunk on the terminals caused the high resistance?
Just need some warm weather in the UK now!
