2009 Aveo5 LT.
Symptoms: The A/C low pressure pipe starts to freeze up, after driving for an hour or so.
Stops cooling passenger compartment.
The Aveo has a 2 speed cooling fan.
For the high speed fan to operate, battery voltage is switched through a relay to the fan.
For the low speed fan operation, a 0.6 ohm resistor, located below, and in front of the battery shelf, is switched in series with the fan motor, to reduce the voltage, and so, the speed of the motor.
If the low speed cooling fan resistor fails open circuit, there will be no low speed fan operation.
There is no indication, to the driver, if this failure occurs.
The low speed cooling fan is normally engaged when the A/C high side pressure reaches approximately 100 PSI.
If the low speed cooling fan fails to operate, the A/C high side pressure can, on a stationary vehicle, with no air flow through the condenser, continue to rise to around 300 PSI. At this point, the Engine control computer engages the high speed fan, to prevent an already critical situation, getting worse.
The A/C system still provides cooling, although noticeably reduced, when the vehicle is stationary.
Continued use of the A/C compressor, pumping into this excessively high pressure will, in time, cause compressor damage.
In my case, the compressor seals began to leak, eventually allowing moisture into the system, and the resulting pipe freeze. I am sure that there are other, far more dramatic, compressor failure modes, including metal pieces circulating in the A/C plumbing.
Surprisingly, there was no obvious damage to the rest of the A/C system, and after replacing the compressor, and performing the mandatory vacuum test, and resulting moisture purge, the system was successfully re-charged, with the appropriate oil, and refrigerant, and now operates normally.
An open circuit resistor failure, is not uncommon, especially when, as in this case, it is being used at high temperature, under hood, and dissipating a considerable amount of power, in the fan circuit.
It is rather sad that a simple hole in the vehicle diagnostic coverage, can result in considerable damage, and expense.
The resistor is widely available for $18 to $20.