Auto Repair Q&A



Cooling System










Auto Repair Products

I have a 1992 cadillac seville my heater's not working what can be the problem?

You can manually "scan" this

You can manually "scan" this vehicle for hvac faults. This will assist us in diagnosing. Using the CCP (Climate Control panel) depress the "Off" and "Warmer" buttons at the same time and continue holding until all segments on the CCP and FDP (Fuel Data Panel) light up. Release both buttons and watch the display on the FDP. There are two types of trouble codes displayed. Codes that are displayed with an E before the numbers refer to the Powertrain Control Module (PCM). Codes that are displayed with the letter F before the number are Body Control Module (BCM) codes. Codes that have an EE or FF are current trouble codes and should be diagnosed first. There are four F codes that will affect the outlet temperature for the heater. F10 for an Outside Temperature Sensor circuit problem, F13 for an In-Car Temperature Sensor circuit problem, F15 for a Solar Sensor circuit failure and F40 for an Air Mix Door problem. After all diagnostic trouble codes are displayed, the FDP will display 7.0. This indicates the system is awaiting further input from the technician. Both PCM and BCM data can be displayed and outputs can be commanded by use of various buttons on the CCP and the FDP. Many scan tools will be unable to access some functions. To access climate control data depress the "Outside Temp" button on the CCP panel. The display on the FDP will switch from 7.0 to F.8.0. Now depress the "Hi" fan button, the display will change to P.2.0 and will switch periodically for a moment to another number. This second number is the value for that particular parameter. By using the "Hi" and "Lo" fan buttons you can move up or down in the parameter values. There are six parameters for lack of heat. They are P.2.1 for Engine Coolant Temperature, P.2.2 for commanded Air Mix Door position, P.2.3 for actual Air Mix Door position, P.2.5 for the In-Car Temperature Sensor, P.2.6 for actual Outside Temperature Sensor, and P.3.2 for the Sunload Sensor value. The Sunload Sensor is only used on 1991-1993 models. The temperature sensor readings are displayed in degrees Celsius and the Sunload Sensor is displayed in counts from 0-255. Review each parameter and then proceed to the appropriate step for the diagnostic trouble code present or the parameter that is displayed incorrectly. Let me know how this goes.