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Confusing A/C issue.... Help!


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Hi everyone, new to the forum! I will get straight to the point, recently just purchased a 2007 Cadillac CTS 3.6L. The ecu went bad out of no where leaving with me with my traction control light on as well as my engine light, security system and the airbag light it's been like this for a few weeks now. Then a couple days ago my A/C started acting funny, sometimes it will be cold sometimes hot, I either have to restart the car to make it cold or throw it in neutral turn the ac button off then turn it back on and throw the car back in drive.. Or sometimes if i roll the window down for a second it becomes cold again as well. Very strange if you ask me. Also it will pulsate, meaning the air will blow hard the soft but in a fast motion. I'm in need of help!!

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When the A/C blows warm air, open the hood and feel the A/C pipes where they pass through the firewall. If they are cold, the problem is likely a blend door actuator. If these cars have an A/A accumulator (large aluminum cylinder on the low side of the A/A system, that should be cold as well.

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

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When the A/C blows warm air, open the hood and feel the A/C pipes where they pass through the firewall. If they are cold, the problem is likely a blend door actuator. If these cars have an A/A accumulator (large aluminum cylinder on the low side of the A/A system, that should be cold as well.

Thank you for the reply. Would you by any chance know where the blend door is located on the car? I am assuming it is beneath the dash?

And the blend door problem would make my ac go from cold to hot while driving? Some times the lines are cold and condesate but other times they also are hot.

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The A/C lines go from cold to hot where they enter the firewall? If so, it sounds like the compressor is shutting down for some reason. Its possible the clutch air gap is too wide causing it to disengage.

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

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Honestly that sounds more plausible. Right now I'm in school for HVAC but this is more complex than home a/c. To me it seems like when the compressor is going to cycle, the clutch will sometimes not engage but I'm not sure if that could happen I would think if it's bad, then it's bad.

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Honestly that sounds more plausible. Right now I'm in school for HVAC but this is more complex than home a/c. To me it seems like when the compressor is going to cycle, the clutch will sometimes not engage but I'm not sure if that could happen I would think if it's bad, then it's bad.

I think automotive A/C is simpler than home A/C other than it is crammed into a small area. The compressors in automotive systems are more complex since they need to deal with a rotating shaft and the sealing challenges that go along with it. Automotive systems are more prone to leakage due to the connections in the tubing and vibrations where home units have brazed connections.

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

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Honestly that sounds more plausible. Right now I'm in school for HVAC but this is more complex than home a/c. To me it seems like when the compressor is going to cycle, the clutch will sometimes not engage but I'm not sure if that could happen I would think if it's bad, then it's bad.

I think automotive A/C is simpler than home A/C other than it is crammed into a small area. The compressors in automotive systems are more complex since they need to deal with a rotating shaft and the sealing challenges that go along with it. Automotive systems are more prone to leakage due to the connections in the tubing and vibrations where home units have brazed connections.

Yeah that is very true actually! So do you have any idea of what I should do? Or at least start with?

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Yeah that is very true actually! So do you have any idea of what I should do? Or at least start with?

Check the A/C clutch air gap with a feeler gage. It should be .020-.030". If the gap is OK, the problem would appear to be a control issue which is going to require a service manual to troubleshoot.

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

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