Cadillac Repair/1992 ECON


I have a 1992 Cadillac and when I push auto on the dash for heat ECON comes on and when I push the red for heat to like 90 it stops blowing out of the front vents and it reroutes to the defrost vents but it does not blow out hot air when I turn down the heat to like 60 it reroutes to the front vents but blowing cold air. The service light comes on to service airconditioner


First the a/c is a separate system from heat and should not be your concern at the moment.
You have a vacuum issue under the dash not opening the correct plenum doors. There are doors that control the direction of the air.

As for the heat, could be numerous issues. Low radiator, bad radiator cap, plugged cooling system. Bad heater control valve at engine.

With engine warm, touch all the hoses to make sure they are hot. Check the hoses leading to the fire wall where the heater is located. If only one warm, either circulation problem in heater or heater control valve not engaged.

The heater control valve is also operated by vacuum, so you need to find your vacuum leak. It could be at the control as well.

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Rob Painter


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?


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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