Refer to the service manual for your house air conditioning system for guidance on what your air conditioning unit looks like and where it is likely located.
Regardless of the outlet type, ensure the air conditioner is firmly plugged into its outlet.
If you’re not sure how to turn on your particular air conditioner, check the instructions that came with the system.
With dial style thermostats, simply turn the dial all the way to the left.
Set any bolts you remove from the air conditioner case someplace safe to reinstall when you reassemble the case.
If you still can’t find the valve, look through your service manual or search for your air conditioning model online to find a diagram that can assist you.
The bulb will look like a cylinder with tapered edges - almost like a metal tootsie roll that’s still in its package. Do not detach the bulb from its line. You only need to remove it from the bracket where it’s seated.
You don’t have to raise the temperature much, so the warmth of your hand is plenty. You may want to use a cup of warm water just to free up your hands while you wait for the bulb to warm.
The valve may engage sooner than 15 minutes. That is considered the top end of the waiting period. Avoid switching hands or removing the bulb from the water at all during this time.
The expansion valve will audibly click and you’ll likely even be able to hear the refrigerant begin to flow. Return the sensor bulb to where you found it if the expansion valve worked properly.
If you have trouble locating the air conditioning unit in your vehicle, refer to your repair manual for guidance.
The high side charging port will be a nozzle on a metal line coming from the air conditioner. Of the two on your air conditioner, it will be higher on the engine. If you don’t hear the connection click, it isn’t tight yet.
Make sure the connection clicks. Otherwise, the refrigerant may leak out.
Make sure the vehicle is in park and the parking brake is engaged before you start it. Leave the engine running for the remainder of the test.
In many vehicles, there is a “Max A/C” button or setting. Make sure to turn that on.
When the arrows stop bouncing around the gauge, that’s considered stabilized.
The sensing disc may be mounted close to the air conditioner or even on the firewall that divides the engine bay from the vehicle’s cabin. If you have trouble locating it, refer to an application specific repair manual for further guidance. The expansion valve itself will look like a metal rectangle with a disc on the top.
Once it’s frosted over, wait a few minutes to see how the expansion valve responds.
If the high-pressure gauge does not show a drop and return in pressure, then the valve is bad and needs to be replaced.
