dosbevos Posted April 14, 2004 Report Share Posted April 14, 2004 on the back of the ECC I can jump between (H=power, to D=A/C request output) and A/C works, but will not work using AUTO button - the ECC is new. Is there a sensor or other device that controls the AUTO button input? The AUTO button goes back to ECON when released Rdosbevos Link to comment Share on other sites More sharing options...
KevinW Posted April 15, 2004 Report Share Posted April 15, 2004 I don't have a 1990-92 D-car manual for reference, but I recall the system monitors low side temperature, and therefore could inhibit compressor operation if it detects a low refrigerant level. BTW, what is the reported outside temperature? Check for diagnostic trouble codes - I think they'd be under pointer "01"; someone with a manual would be able to offer more specific info. ___________________________________________________ Link to comment Share on other sites More sharing options...
dosbevos Posted April 15, 2004 Author Report Share Posted April 15, 2004 thanks kevinW fot your reply, my location is pasadena texas temp is 75, low side reading is 32-high side is 230. Every thing works but the AUTO button. there are no trouble codes on computer using check engine light. outside, inside, and evap. temp. sensors all show resistence and the low press. switch checks OK Rdosbevos Link to comment Share on other sites More sharing options...
dosbevos Posted April 16, 2004 Author Report Share Posted April 16, 2004 hello KevinW - by pushing OFF and WARMER buttons I read 48,110,112,132 but with no prefix Link to comment Share on other sites More sharing options...
KHE Posted April 16, 2004 Report Share Posted April 16, 2004 hello KevinW - by pushing OFF and WARMER buttons I read 48,110,112,132 but with no prefix Codes 110, 112, and 132 are history codes for codes 10, 12, and 32 respectively. I can look in my '93 Fleetwood Brougham service manual tonight to see what code 48 is. The code IDs may be the same from '90-'95 RWD cars. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
dosbevos Posted April 16, 2004 Author Report Share Posted April 16, 2004 hello KevinW, thanks again for your help, code10=OAT sensor and code12=low side temp sensor-do you know where these sensors are located on the 91 cad? how do you like your fuel injected, 4-speed, small block in the 93 cad? health&happiness - dosbevos Link to comment Share on other sites More sharing options...
KHE Posted April 16, 2004 Report Share Posted April 16, 2004 hello KevinW, thanks again for your help, code10=OAT sensor and code12=low side temp sensor-do you know where these sensors are located on the 91 cad? how do you like your fuel injected, 4-speed, small block in the 93 cad? health&happiness - dosbevos I wouldn't worry about the history codes - they were resolved on their own. I would concentrate on the current codes first which in your case is the code 48. I'll look up the code 48 in the '93 shop manual to see if it is related to the A/C system. The OAT sensor is located right behind the grill (at the front of the car). I believe the low side temp sensor is located on the A/C evaporator behind the dash. I love my '93! I purchased it new. My only regret was not waiting until the '94s were out for the LT1 Gen2 engine....Oh well - it's still one hell of a car - I store it during the winter and even after 11 years, it still looks like it came off the showroom floor. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
KHE Posted April 17, 2004 Report Share Posted April 17, 2004 The codes are different between the '90-'92 and '93 cars. There was not a code 48 in my '93 manual. You might ask your local dealer to look it up for you. You can often find the 1991/1992 Brougham Shop manuals on ebay for a reasonable price. www.helminc.com has new shop manuals. Don't waste your money on a Chiltons or Haynes manual - get the factory service manual. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
dosbevos Posted April 19, 2004 Author Report Share Posted April 19, 2004 thanks for your help KevinW, the OAT sensor was right where you said, I checked it and I think is OK, I have resistence on the evap inlet temp sensor so I don't think thats the problem either. Do you have any more ideas or checks I can make.I feel I'am over looking something simple. I'am taking your advice on the service manual for the 91 and 92 they seem to use a different ECC than other Cads. thanks again Rdosbevos Link to comment Share on other sites More sharing options...
KevinW Posted April 19, 2004 Report Share Posted April 19, 2004 On some systems, compressor operation is inhibited when the ambient temperature is close to or below freezing. If the OAT circuit is open, it will think it's -40 F. Also, it's possible that compressor operation may be affected if certain diagnostic trouble codes are set. Have you tried clearing the codes? ___________________________________________________ Link to comment Share on other sites More sharing options...
KHE Posted April 20, 2004 Report Share Posted April 20, 2004 I looked up the refrigerant pressures in my A/C book and it specifies 22-29 psi for the low side and 165-200 psi for the high side at 80F and high idle. Were your pressure readings taken at high idle? If so, you might be slightly undercharged and that would be the reason for the ECC defaulting to ECON (to prevent the compressor from being damaged). The only way to know for sure would be to recover the refrigerant and weigh the amount recovered and then compare to the specification decal on the accumulator. As KevinW said, some codes may affect the operation of the compressor and not having a '91/'92 manual, I don't know what code 48 is but I would bet it is a low refrigerant code. I would find out what the code 48 is and begin the troubleshooting there. Post back your findings. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
dosbevos Posted April 20, 2004 Author Report Share Posted April 20, 2004 hello KevinW - I grounded the OAT circuit and cleared the codes, I read code 48 now which I think is a low pressure code, I also have only 650 ohms on the low pressure switch circuit, - should that be a closed switch to ground? thanks Rdosbevos Link to comment Share on other sites More sharing options...
KHE Posted April 20, 2004 Report Share Posted April 20, 2004 If you've confirmed that code 48 is a low refrigerant code, then add one can of R-12 to the low side port (on the accumulator). You will need to get the R-12 hooked up and then clear the code so the system will run the compressor to pull in the R-12 without resetting the code. Be sure to confirm that the code 48 is a low refrigerant code before adding refrigerant so you don't overcharge it.... Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
dosbevos Posted April 21, 2004 Author Report Share Posted April 21, 2004 hello KevinW - I haven't confirmed the 48 code, but think I found the problem - the low pressure switch on back of compressor is open. I don't think the switch can be removed without evacuating the system, if thats the case I'll go to 134A or what do you think about Freeze 12, it's $6.99 a can - Thanks again for all your help Link to comment Share on other sites More sharing options...
KHE Posted April 21, 2004 Report Share Posted April 21, 2004 If it were my car, I'd keep it R-12. Freeze 12 is 80% R-134a and 20% some other refrigerant that circulates the oil in the system. R-134a will not circulate the R-12 mineral oil. A proper R-134a conversion will cost more than a charge of R-12. To convert to R-134a, the system needs to be flushed to remove as much mineral oil as possible. The accumulator needs to be changed as the dessicant material traps a lot of mineral oil. The o-rings at all of the line connections may not be compatable with R-134a and might need to be changed. Don't be tempted to use a $30 Walmart "Compressor Death Kit" as compressor destruction is a certainty... Try to find an independent air conditioning shop and have them recover the R-12 from the system. You can then replace the switch yourself and have the shop evacuate and recharge the sytem for you. If you are positive on the diagnosis, it might not be much more money to let the shop change out the switch for you. I would definitely find out what the code 48 is before going forward. It could be that you are just undercharged and a booster charge of R-12 would be all that is required. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
KevinW Posted April 21, 2004 Report Share Posted April 21, 2004 Hello dosbevos, don't forget to say hi to Kevin E. too. The low pressure switch on the R-4 compressor should be closed when the high side is above ~30 psi. If the system has a good charge, you could by-pass this switch and be careful to avoid running the compressor at the first sign of refrigerant loss (higher than normal vent discharge or accumulator surface temperatures, etc.). As KHE noted, Freeze 12 is 80% R-134a, and I believe the remaining 20% is R-142b. The latter does not return mineral oil very well, which could starve a high-mounted compressor in a few months. The secret to getting R-142b blends to work acceptably is the addition of ~4% isobutane, as can be found in the R-12 drop-in replacement, R-406a. ___________________________________________________ Link to comment Share on other sites More sharing options...
dosbevos Posted April 27, 2004 Author Report Share Posted April 27, 2004 KevinW, thanks for all your help- my problem was two shorted wires in the wiring harness going to the compressor clutch - the two wires were the Low Pressure Switch and the 12 v. clutch wire, the short burned the Low Pressure Switch open. Thanks again - Rdosbevos Isolate and Simplify - anyone need the Electronic Climate Control for 91-92 Cad RWD? Link to comment Share on other sites More sharing options...
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