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Jared D
Jared D, ASE Certified Technician
Category: Toyota
Satisfied Customers: 1813
Experience:  Shop Supervisor at County Fleet
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2012 toyota camry with 16k miles. A/C works very

Customer Question

2012 toyota camry with 16k miles. A/C works very intermittently. Changed compressor and problem persists. System was properly evacuated and held vacuum. This car does not have a compressor with a clutch and the A/C does blow cold when it works. Took car to Toyota and they said they could find no codes showing that indicated a problem but did agree that the A/C was not working. They suggested changing the compressor but that has already been done. Have begun diagnosing individual circuits but before I get too far I was hoping someone had encountered this problem before and could point me in the right direction. Proper amount of R134a was put back in the system and when the A/C is blowing cold the pressures are correct. When the A/C is not working pressures on both sides are ambient.
Submitted: 1 year ago.
Category: Toyota
Expert:  Jared D replied 1 year ago.


Has anyone looked at replacing the AC amplifier? It's likely that the compressor isn't coming on because the amplifier isn't sending the correct signal to the compressor to get it to run. It's fairly easy to replace if you would like to attempt it yourself. I can send a diagram if you would like to see how it's done.

Customer: replied 1 year ago.
Please send the diagram through. I have been going through the diagnostic tree in the Chilton's online manual and after checking the voltage and resistance in the pressure sensor (voltage ok - resistance at 4 ohms) the next step was to do the same on the amplifier end. I just didn't want to get up under the dash to get at it if that wasn't the issue. The manual says that I have to remove the air bag under the dash and that made me a little nervous. The book says that the resistance at the pressure sensor plug (A55) should be less than 1 ohm and I got 4 ohms. Could this indicate an issue with the amplifier?
Expert:  Jared D replied 1 year ago.

That high ohm reading kind of sounds like low freon pressure- I'm sure someone has checked pressure levels though right?

Expert:  Jared D replied 1 year ago.

Here is what toyota publishes on replacing the amplifier:

Expert:  Jared D replied 1 year ago.

Here is the note on the airbag:

Customer: replied 1 year ago.
Pressures are good. When the A/C is working the pressures are in the proper range and when the A/C is not both sides are about equal. I believe that when the pressures are equal it indicates that the R134a is equalized in the system and at its normal vapor pressure for the given ambient temperature. The high ohm reading was taken with the pressure switch plug removed and the ignition off as the manual directed; I assume to check for a short in the wiring harness. The next step in the diagnostic tree was to get at the amplifier and check voltages and resistances there. Again, with all the looking online I have done I cannot find anyone that has solved this problem and without any codes being shown I was hoping that someone could point me in the right direction. The problem is that the A/C works sometimes so the problem is intermittent - will a faulty amplifier cause intermittent A/C?
Expert:  Jared D replied 1 year ago.

If there is a bad circuit in the amplifier the problem would be intermittent, but typically you will see a b1479 trouble code when the amplifier isn't working.- not always though.

So the ohm reading on the pressure switch was with the engine off, that could be normal then I guess, but it still wouldn't hurt to replace the pressure switch if it is sticking high light that.

Customer: replied 1 year ago.
I'll remove the amplifier tonight. It'll take me a few days to get a new one.
Expert:  Jared D replied 1 year ago.

Let me know if you need additional info.

Expert:  Jared D replied 1 year ago.

Your question has dropped to my timed out list.

Please let me know if you need additional help.

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