DIY Auto Maintenance and Servicing Tips

« Back to Home

Is Your Car's Expansion Valve Working Properly?

Posted on

The air conditioning system in your car is similar in many respects to the one within your home, and one thing is for certain, you will rely on it once summer rolls around. You may have heard of some of the major components, like the condenser, compressor and evaporator, but there are a number of other critical pieces as well that all need to function correctly to cool the cabin effectively. The expansion valve, in particular, is frequently overlooked but will need to be serviced correctly or the entire system may fail. What should you know about the air conditioning expansion valve and how can you tell if it's not working properly?

Valve at Work

This expansion valve manages the refrigerant liquid as it flows through the system. Without it, too much refrigerant could cause the evaporator to become overly cold and freeze solid. The valve will also prevent the evaporator core from overheating without enough refrigerant, so, as you can see, it's very important to ensure that the valve is functioning correctly.


If too much refrigerant is allowed to go through the system, then you may jump into the car and notice some frost on the edge of each vent. The temperature inside the cabin will be way too cold even for the hottest day and even if you like frigid temperatures, you need to fix the issue. If the evaporator core becomes frozen, it could damage other parts of the system and lead to a higher bill.

Bad Cycling

The air conditioning system is designed to cycle on or off as soon as it reaches the ideal temperature. If you notice that the compressor is always on, then this could be another sign that the expansion valve is stuck in the open position. Eventually, the compressor will overheat, and the bearings will start to fail and, once again, this can have an effect on other components along the line.


If your system appears to be inconsistent and cannot make its mind up, then you may notice that warm air comes out of the vent one second and cold the next. This inconsistent performance could be due to a bad expansion valve, and you should take the vehicle in for a service as soon as possible.

Being Prepared

When everything is working as it should then your air conditioning system can be a godsend on a typically hot Australian day. To make sure that you don't experience a related breakdown, make sure that you schedule regular car air conditioning service.