QuestionQUESTION: 1st issue - No AC: I purchased my Deville 2 days ago and while on initial test drive I was able to get cold air to blow for about 5 seconds then air stopped, (but fans still blew) and NO SES lights/climate control warnings appeared... the previous owner had the freon-R134 conversion done a year ago and 7k miles w new compressor(old one failed and the replacement caused the conversion to take place)...The econ fans worked today but the AC did not. Also, Service Engine 'SOON' comes on every now and then then goes away... It has never lit up the Serv Engine 'NOW' light. AC compressor looks very new still even from above it sticks out like a gem amongst the other gummy/dirty accessories. Ex owner statres it never worked right after repair so I suspect old codes werent cleared???
2nd issue: I plugged a metal code key in the ALDL port to read codes through serv engine soon but the service engine soon light does the
'12' cadence in a flickering manner the entire time! Its almost impossible to make out the one (1), one-two (2) due to the flickering if there are other codes stored. Do I need a 39.99 cheapo OBD1 scanner due to this problem flicker of the bulb to pull/read the codes from the ECU? It only flickers when the ALDL plug is keyed for code reading otherwise its a solid light upon key forward or when it comes on every now and then when driving.
today after learning about the BCM computer controling the climate control and getting different or non-detailed internet info on how to comprehend the diagnostics after holding OFF and HIGH fan speed buttons to gain entry I am confused as to the entire scope of code reading....in the beginning of getting into diagnostics the codes are F10, 07.0 , F.8.0, then when I hit 'Econ' button it reads E.9.5.... I found I could scroll through w different buttons and I found P20 through P31 w associated values on each.... I could not get anything to change by pushing OFF and HI buttons and seeing E.0.0 then press AUTO to exit.....nothing clears after I try again 10 seconds later...same codes appear. Any way to master clear everything like battery disco for several hours? What would I see exactly if no codes are present? What is the exact way step by step to list actual codes?
Sorry for the long read, I just ordered the factory shop manual and code chart from Helm inc to hopefully clarify the system in the future.
ANSWER: !st issue. The 80's Cadillac's CANNOT be converted to R-134 freon because the low pressure sensor is NOT calibrated for this type of freon and there is NO fix as of this date. You MUST convert it back to R-12.
2nd issue: to get the codes from the 4100 engine via the climate control panel and to CLEAR (erase) them is the FIRST thing you need to do to see if any codes return is done via:
1. Ignition switch ON, Engine NOT running.
2. Simultaneously push and hold the OFF and WARMER buttons for 3
seconds and release them.
3. Codes will appear as either E or EE followed by numbers such as E
15 which would be a HISTORY code or if it displayed as EE15 this
would be a CURRENT code.
4. After the E or EE codes all displayed the F or FF codes would
appear and the screen will stop at .7.0
5. To CLEAR the E or EE codes, Simultaneously push and hold the OFF
and HI buttons until you see E.0.0 and release the buttons.
6. To CLEAR the F or FF codes, Simultaneously push and hold the OFF
and LO buttons until you see F.0.0 and release the buttons.
7. Push and release the AUTO buttons and turn OFF the ignition.
8. Wait 30 seconds and re-enter diagnostics by repeating steps 1 and
2 as stated above and see what codes appear.
Let me know what codes appear.
Disconnecting the battery will NOT CLEAR the codes but will only ADD 2 codes that mean that you removed battery power from both computers.
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QUESTION: Thank you: due to your more detailed explanation of step 5 and 6 I am able to report the 'history' E and F codes are now gone. My car has not flashed 'service engine soon' in 300 miles of driving since.
Next question: Air ride for rear shocks...I discovered the air compressor underhood drivers side was unplugged and there was some previous work hardwiring the black(ground?) since the connector was cracked at this junction....I plugged in and was able to feel the compressor vibrating. Should the car visibly 'lift up' or just compensate at the same ride height for passengers/cargo?
Final question: regarding the R134 not working w/ factory low side sensors...is it possible to "trick" the BCM and install a certain ohm resistor on the positive wire going to the low side pressure sensor? People have done this to fake the post catalytic convertor O2 readings on modified late model EFI cars so I figured its worth a shot? I'm trying to think out of the box to get my AC blowing again. Regards
ANSWER: the rear air ride shocks should inflate to keep the rear of the car level with the front end of the car and maintain this position until weight of over 300 lbs is placed in the back seat or cargo over 300 lbs is placed in the trunk, Then the compressor will run to inflate the air shocks to keep the rear of the vehicle level with the front. Once the weight is removed the pump will exhaust the air shocks so the rear of the car will lower to keep the rear level with the front.
You can do many things with the exhaust sensors to improve fuel mileage with resistors and numerous other sensor modifications. But trying to do this with the low pressure sensor will cause the sensor NOT to read a low refrigerant condition and destroy the AC compressor into continuing to run if a freon leak develops.
---------- FOLLOW-UP ----------
QUESTION: Thanks for previous directions I was able to clear all codes successfully,
2 more issues...
Previous owners of Deville were Canadian and had the fuel/climate displays set to Metric from Standard...the car was originally a US model sold in Colorado. My car is a bar speedometer not the full electronic speedo option that had a dedicated Metric/Standard button to change at the push.....how can I change it back to Standard units AND can I read my engine temp through the Fuel or Clim screens?
2. The 4.1L motor was notorious for overheating and blowing gaskets. Ive heard part to bad design w/ alum block and steel heads but my suspicion is also a typical 80's GM that was purposely engineered to run hot to light off the cat convertor sooner.. My motor has been replaced about 50-55k miles ago (97k) and you can still see the newness of the gaskets and all the hose connections have new clips, coolant is also clean. Is it ok to change the thermostat to a slightly cooler unit to maintain a cooler running car as long as I dont go too low? And what is the factory temp thermostat? 215-220 deg? I was thinking of doing a 180-190 if that was the case as long as it doesnt harm fuel economy or injector pulse. Last thing....when will my electric fans come on? I have not noticed them coming on at all even sitting in traffic and idling in the garage...when I pop hood to watch for them spinning after a long drive they aren't. My concern is over the frail nature of the 4.1L gaskets and fear of blowing something of course....Cars AC does not work and I luckily live in moderate San Diego near the water so daytime temps are 68-85 year round. Would fans not want to cycle on if outside temps are cool enough? Regards
Answer1. Push the ENGLISH/METRIC button to change the display to english. If you want to intermittently see the actual engine temperature follow this procedure.
1. enter into diagnostics until you see the .7.0
2. Push and release the LO button and you will see E.9.0
3. Keep Pushing and releasing the LO button until you see P.0.4 which will display the engine temp in CELSIUS degrees. The only problem is that the CHECK ENGINE LIGHT remains ON all the time while observing the actual engine temp. To EXIT out of the system push AUTO.
2. Do not change the thermostat from the original factory's specificationsof a 220 thermostat. The engine cooling fans will come ON when engine temp hits approx 225 degrees.
