ralphiedee Posted May 2, 2011 Report Share Posted May 2, 2011 I have the manual for the car but this requires a bit more than looking at the obvious. Symptoms are the following: I get the yellow LED lights and air blowing from the heater on Low and hi only no lights or air flow for Defrost or economy. heat only (if I lower the temp to 60 still get hot air. besides the obvious ( temp control switch ) would there be any reason why I do not get the lights for the above mentioned? My next step? any help? rd Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 2, 2011 Report Share Posted May 2, 2011 Some cars, including probably yours, use resistors in the switch circuit for low and medium fan speeds. The medium power resistor may be burned out. Insofar as the LEDs are concerned, they may be on the circuit after the resistor, so that would make the medium speed resistor your only culprit. If the LED feed is dielectric from the switch, then the resistor is probably good and the switch is bad. Insofar as cold air is concerned, I would start out with the OBD codes. Yes, the 1984 Cadillac has OBD. Check with your owner's manual. I have seen early OBD material (short specified connector pins, count "check engine" blinks for a code) in a Chilton's manual, but your true resource is a FSM. I would get all three volumes - underhood wiring (which you have), chassis, and body. Doing what you can without a FSM, the usual troubleshooting procedure for the A/C are in order. Begin with a set of Freon hoses and gauges, and by checking for voltage on the compressor clutch wiring, and seeing if you can't get the compressor to turn on by applying 12 Volts to the clutch terminal. If you find that the system is still charged at all and the compressor seems to turn OK, charge the system to specs, using a direct 12 Volts to the compressor clutch if you have to. Rent a sniffer and make sure that it isn't leaking at the beginning of the charging process, and fix any leaks before you waste Freon. Then, shut everything down, disconnect the ground cable of the battery for five minutes, then reconnect the battery and see if it works. If not, then go through electrical troubleshooting with the wiring to the compressor and in the A/C controls under the dash. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
ralphiedee Posted May 2, 2011 Author Report Share Posted May 2, 2011 I have the manual for the car but this requires a bit more than looking at the obvious. Symptoms are the following: I get the yellow LED lights and air blowing from the heater on Low and hi only no lights or air flow for Defrost or economy. heat only (if I lower the temp to 60 still get hot air. besides the obvious ( temp control switch ) would there be any reason why I do not get the lights for the above mentioned? My next step? any help? rd Link to comment Share on other sites More sharing options...
Ranger Posted May 3, 2011 Report Share Posted May 3, 2011 I think the resistor is located on top of the HVAC housing just below the base of the windshield. It's set into the air stream to cool it. The LED light is probably burned out. I had one out on my '83. I think you have to replace that panel if I remember correctly. Link to comment Share on other sites More sharing options...
KHE Posted May 3, 2011 Report Share Posted May 3, 2011 Back in the day, those climate control panels could be rebuilt - dealers had reman units on the shelf. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 3, 2011 Report Share Posted May 3, 2011 If they were replaced in any volume back in the day, then I would do a web search on the part number. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
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