Air Conditioner Puzzler... Any Ideas?

[Rodger Wilco]

Originally Posted by CTScott

There is a pressure transducer next to the sight glass on the aluminum tubing. A few have had that go bad resulting in a similar condition. The best first step would be to have the pressure checked to see if you are actually low on refrigerant or not. Some of the DIY refill kits have a gauge that gives you a general idea, but that just measures the low pressure side. A proper testing will measure both to verify that the compressor is functioning. You can actually pickup a DIY manifold gauge set for about $60, if you want to test it yourself.

Hey thanks for the response guys. Sorry for the late response I have been out of town for work a lot and away from my computer. Unfortunately I don't think we are out of the woods yet on this one.

I first went to the Auto Zone and bought the $30 can of refrigerant and hooked it up. The System took about half the can and I took this as a good sign. Buutt.... the AC did not work at all after that, so I knew the pressure was all off.

So I took the car to a friend of mine who works at a VW dealership. He hooked it up to a machine that flushed the refrigerant completely, checked for leaks and filled it to the exact proper level. (.86lbs I believe per the placard underneath the hood).

After that I was sure that we had it fixed. Sadly I am experiencing the same issues; the AC will disengage at random/ will not engage when I need it. (and I really do need it, this is PHX!)

@CTScott tell me more about this pressure transducer...

One thing I have noticed is that the big fan behind the radiator (what I would calla clutch fan) is not always on when the AC is selected on. It was my belief that this fan needed to be always running with the AC on... Anyone know for sure?

[CTScott]

Originally Posted by Rodger Wilco

Hey thanks for the response guys. Sorry for the late response I have been out of town for work a lot and away from my computer. Unfortunately I don't think we are out of the woods yet on this one.

I first went to the Auto Zone and bought the $30 can of refrigerant and hooked it up. The System took about half the can and I took this as a good sign. Buutt.... the AC did not work at all after that, so I knew the pressure was all off.

So I took the car to a friend of mine who works at a VW dealership. He hooked it up to a machine that flushed the refrigerant completely, checked for leaks and filled it to the exact proper level. (.86lbs I believe per the placard underneath the hood).

After that I was sure that we had it fixed. Sadly I am experiencing the same issues; the AC will disengage at random/ will not engage when I need it. (and I really do need it, this is PHX!)

@CTScott tell me more about this pressure transducer...

One thing I have noticed is that the big fan behind the radiator (what I would calla clutch fan) is not always on when the AC is selected on. It was my belief that this fan needed to be always running with the AC on... Anyone know for sure?

The pressure transducer is mounted to the aluminum tubing, right next to the sight glass.

The fan will run whenever the compressor is engaged. If the AC ECU decides that it is not happy and it shuts off the compressor the fan will also shut off (if it doesn't need to be on for the coolant).

[Rodger Wilco]

Originally Posted by CTScott

The pressure transducer is mounted to the aluminum tubing, right next to the sight glass.

The fan will run whenever the compressor is engaged. If the AC ECU decides that it is not happy and it shuts off the compressor the fan will also shut off (if it doesn't need to be on for the coolant).

So just to make sure I am understanding you correctly, the fan doesn't necessarily need to be on anytime the AC is working properly only when the compressor is actually compressing?

How do I check a pressure transducer? How would I know if mine was bad?

Thanks for getting back to me so quickly!

[CTScott]

Originally Posted by Rodger Wilco

So just to make sure I am understanding you correctly, the fan doesn't necessarily need to be on anytime the AC is working properly only when the compressor is actually compressing?

How do I check a pressure transducer? How would I know if mine was bad?

Thanks for getting back to me so quickly!

Correct - Typically though with the simple A/C system of the yaris, almost the entire time the button is pressed the compressor is engaged.

For the transducer you can measure the voltage on the grey wire with the AC on and you should see between 0.76 and 4.74 volts.