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Cadillac Repair/04 cadillac deville blows in back seat but not front

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Question
I have a 04 cadillac deville dts. The heat and ac will not blow in the front of the car but the ones in the backseat will blow heat and ac. What do I need to do to fix this? What is causing this?

Answer
Hello,

The most likely answers are not that hard to determine but locating the problem that can be more difficult.
To prevent from guessing and replacing parts that did not have to be replaced costing you time, money and frustration, I highly recommend obtaining a factory service manual. Do not screw around with general information with Haynes, Chilton or the like.
You should be able to purchase one on EBay or Craig's. In my view, this is one of the best investments for older cars is the factory service manual, because even the novice can fix anything wrong with the car.
Diagnostic flow charts will walk you through just about any problem you may encounter over the years.
I am not at the vehicle to determine the flow of the a/c and heat to the rear, which puts me at a disadvantage answering your question. From your discription, there are only two things that I feel could be your problem. One would be a bad blower and the other would be a vacuum issue.
Direction of air flow is controlled by vacuum lines and mode doors. A pinched or broken vacuum hose, a stuck or binding mode door can create a situation that air does not flow where it is supposed to go.The manual is required to locate these hoses in order to diagnose and repair these problems.
To check the blower motor which should be mounted under the hood in the passenger side close to the firewall, have the ignion on with blower speed of he high. Put your hand on the blower and see if it is operating. If not go to glove box and check owners manual for multiple fuse boxes and check blower fuse.
There are many more steps for diagnoses here. Some will change the blower motor to find there was another problem. Having a service manual prevents that and proper diagnoses for xes the problem the first time.

Good luck!

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Rob Painter

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Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?

Experience

Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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