audioguy99 Posted April 21, 2006 Report Share Posted April 21, 2006 I just recently replaced the blower motor on my 95 SLS and now the AC is not blowing cold. It was intermittent and now seems to blow hot all the time. I get the AO12 code and there's obviously a problem that is keeping the compressor from kicking in. I have the big manuals and was looking with my limited knowledge. I disconnected and reconnected the sensor and it seems that the connections are good. In the troubleshooting section for the Low Side Temp Sensor, I followed the procedure and looked at the AD28 data. The reading changes between -39 and up. According to the manual there is no problem in that range and I should refer to "intermittent problem" section, which I can't seem to find. Being that the reading is so low, it borders on being a sensor or open somewhere. I also followed the chart for "No compressor but blower working". The compressor engages, which leads to checking the sensor. The readings seem normal, which would point to the ACP being bad. How do I decipher and discern all of this?? Is there a bypass that would somehow get the compressor to get back in? Would any repair shop be qualified to deal with this or is this more strictly a dealership issue? Any help or advice?? I'm not made of money these days so I'm trying to get an idea of what I'm looking at - if it's not a DIY job. Thanks in advance, Jonathan Link to comment Share on other sites More sharing options...
jfreezn Posted April 22, 2006 Report Share Posted April 22, 2006 I have the big manuals and was looking with my limited knowledge. I disconnected and reconnected the sensor and it seems that the connections are good. In the troubleshooting section for the Low Side Temp Sensor, I followed the procedure and looked at the AD28 data. The reading changes between -39 and up. According to the manual there is no problem in that range and I should refer to "intermittent problem" section, which I can't seem to find. Being that the reading is so low, it borders on being a sensor or open somewhere. Jonathan, -39 is way too low and unatainable with R134. I would reread the section that says this is an acceptable reading. That sensor sounds bad to me. most sensors can be changed without loss of freon, the pressure types having a schrader valve, and temperature type merely a surface contact where they screw in. Regards. Jim in Phoenix Link to comment Share on other sites More sharing options...
KHE Posted April 22, 2006 Report Share Posted April 22, 2006 The low and high side temperature sensors do NOT have schrader valves. Those sensors are on the line that runs along the firewall (on each side of the orifice tube). The refrigerant must be recovered before either is removed or you risk injury from frostbite. The low and high pressure sensors have schrader valves and can be replaced without recovering the refrigerant. The low pressure sensor is on the low pressure (large) line that runs from the accululator to the evaporator (next to the strut tower). Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
KHE Posted April 22, 2006 Report Share Posted April 22, 2006 Is the AO12 code the high side temperature open circuit code or is it the short circuit code? If it is the open circuit code, unplug the sensor, jumper the connectors on the wire harness and enter diagnostics - if the code changes to the high side short circuit, the sensor is bad. If the code is the short circuit, unplug the sensor and enter diagnostics - if the code is now the open circuit code, the sensor is shorted and must be replaced. If there are no changes in the code, there is a problem with the wiring. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
audioguy99 Posted April 22, 2006 Author Report Share Posted April 22, 2006 Is the AO12 code the high side temperature open circuit code or is it the short circuit code? If it is the open circuit code, unplug the sensor, jumper the connectors on the wire harness and enter diagnostics - if the code changes to the high side short circuit, the sensor is bad. If the code is the short circuit, unplug the sensor and enter diagnostics - if the code is now the open circuit code, the sensor is shorted and must be replaced. If there are no changes in the code, there is a problem with the wiring. Code AO12 is simply Low Side Temp Sensor. According to the low reading it would be an open rather than a short. I guess I need to jumper the connectors. Is there a "proper" way to do that other than just using wire to connect the two? Are these sensors going bad a common problem? Of course, the car is almost 12 with 194k miles. Thanks for the help. I'll check into it further now. Jonathan Link to comment Share on other sites More sharing options...
KHE Posted April 22, 2006 Report Share Posted April 22, 2006 Unplug the sensor and jump the harness connector with a small piece of wire - you don't want to distort the connectors. Make sure the temporary connection does not short against something. Turn the ignition to ON and then check the codes - the AO12 should now be a "history" code and a new code should be "Current" The new code should be the low side temp sensor short. If it is, the wiring is probably OK - remove the jumper. If the DIC did not display "Low Refrigerant" then the system probably has a full charge of refrigerant but you will need to have a shop recover the refrigerant so the sensor can be replaced and then the system must be vacuumed down and recharged. I wouldn't consider the sensor failure a common problem on a 12 year old car with 194,000 miles on it. At that point, the sensor doesn't owe you anything. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
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