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'94 STS code A012 question, please


Mosko

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I have replaced the compressor, accumulator, and an initial charge but am getting the A012 code and the compressor won't run. I have tried clearing the code but it is listed as current and seems to return unless I am not getting it cleared. I am at the point of assuming that there is a bad sensor in the low side. Is this sound thinking, and if so where is the sensor located.

Thanks, Mosko

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Get the refrigerant can all hooked up to the system, burp the air from the charging hose, then clear the code and start the engine. The system will pull in the refrigerant before the code returns.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Thank you for the reply, I appreciate it very much!

I manually pulled up the relay and have a good charge. The air is cold and every thing is normal other than the A012 code. This code seems to prevent the relay from energizing, so therefore the system is effectively inoperable.

This returns me back to the original question, Where is the low side temp sensor? Is it the one between the accumulator and the evaparator in the large line?

What is the procedure to test the sensor to determine whether the sensor is at fault or the wiring to that device?

Thanks, Mosko

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That is the inlet temp sensor. It is right behind the orrifice tube (at least on my 95 STS). You'll have to purge the system to change the sensor. It's about $20.00. While you are there, make sure that your orrifice tube is inserted correctly (arrow into evaporator), if it is inserted backwards, it will break the inlet temp sensor.

James

1999 STS 65k

1995 STS 127k

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Just to clarify, A012 is the inlet temp sensor, not to be confused with the low side pressure switch (sensor on the big line you described in your post). The sensor you are looking for is on the skinny line from the evap closest to the firewall. It's the line that the orrifice tube is installed in and there are 2 wires coming from it. Realize that if the sensor is physically broken, you may consider purging the system with mineral spirits be cause you don;t want to wreck your new compressor with debris in the lines. (been there, done that). Good luck.

James

1999 STS 65k

1995 STS 127k

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The list that I have indicates that the code A012 is " Low Side Temperature sensor curcuit", it does not mention "inlet". The switch you are referencing is in the "high side" of the circuit between the compressor and the evaporator is it not?

Could the "Low" and "High" terms used in these codes refer to high and low as it pertains to the orifice tube? Meaning the one to the right (drivers side) would be a higher pressure than the one after the orifice tube, which would probably be at lower pressure due to the loss across the orifice tube?

Mosko.

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Hey thanks hiljak! I thought about what you said about the switch. I see now that the high and low side temperature sensors do reference high and low across the orifice tube.

I unpluged the sensor and stuck a resistor in to shunt the signal to about 2.5 VDC to the ACP and she worked like a charm.

It won't cycle I don't think but it works and the problem will be solved when I get a new sensor tomorrow.

Thanks for all you help guys!

Mosko

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