Question-------------------------
Followup To
Question -
3 weeks ago, the compressor on my '97 Concours let go. I replaced all the key components, pulled the vacuum, charged the system, and was back in business. The system ran great till yesterday when the "Very Low Refrigerant" message popped up. I checked the freon level and it was fine. The low pressure cuttout switch is made, with power going through it, but the message won't go away and the computer keeps the compressor off. Your help is greatly appreciated.
Answer -
Hi Ray, With the engine off and the key on after sitting overnight you need to test the temp. sensors and see if they are all the same and that all the pressure sensors read the same. If one is out of range then that will cause the message to be displayed. Then after replacing the part you will need to clear the codes or the compressor won't engage. When you checked the freon level did you hook up a gage to both sides at the same time to check for restictions and both sides read the same? Bill
Followup -
Bill, I dug through the service manuals and figured out how to read the DTC's from the console and you were on the right track with the temp sensors. I was getting DTC B1347, that basically says the temperature drop on the low pressure side was dropping too fast. I evacuated the system and pulled the orfice tube and sure enough, it had trash on it. I suppose it was some I had missed when the previous compressor let go. Now I've got another question. When I went to charge the system again, the compressor wouldn't kick it. I got DTC B1348 - Very Low Refrigerant Pressure. I checked the pressure sensor and it had power going through it. So I pulled the plug out and jumped it with a clip. The compressor kicked in and I charged the system and it blows ice cold again. Here's the weird part, I hook the plug back into the pressure sensor and the compressor won't kick in. I get DTC B1348. It has power coming in and out but still no compressor unless I jump it. According to the service manual, it's a standard set of contacts that open on low pressure. Is there a minimum voltage that the programmer is looking for? I can only assume that the contacts in the switch are corroded and maybe not passing enough voltage, but I wanted to know if I'm on the right track before I evactuate this thing again. It's my dad's car and he out of town, but only for another week. By the way, how's the best way to check the temperature switches? Do know what type of thermocouple they are or RTD? Thanks for the help.
AnswerHi Ray, The best way to test this system is to use the onboard diagnostics to see what the sensor is showing and then to unplug the connector and see if the statis has changed. If it does then the wireing is good and the sensor is at fault providing that the freon pressures are normal. Sounds like to me that you have already kinda done this and if the pressures are the same on the low and high sides with the engine off then replaceing the switch will cure your problem. There really isn't a good way to test the switch just to eliminate everything else and then replace it if everything tests good. Sorry I took so long to return the e-mail. Hope this gets the a/c working normal. Bill
