Anyone got a good check list or sheme for troubleshooting that error in a logical order?

 

I might get some boos and hisses for this, but I'd bring it to a reputable garage first and have them test it to see if it leaks first. If not, recharge. I just recharged my 1990 vette with R-12 to the tune of $389

Alternatively, I've put the new refrigerant R134a into a freon R12 system (not in my vette, but in another similar aged vehicle) and it worked just fine despite what many people will say. Being that 134a is so cheap, you could just cobble up the right adapters, pump it up and see how it does. Supposedly it's a bad idea for two reasons:

a) The oils necessary in R134A are not compatible with the R12 systems leading to deterioration in the hoses and most importantly the compressor
b) You haven't taken the air that has leaked into the system out

Now I did this in a beater POS car that frankly I wasn't going to pay to recharge with R12 and didn't care a whole lot if the compressor went out since without a recharge it was useless to me anyways. I can report that several years later, it continued to run just fine. I must have had a very small leak as I did need to put in a new can of R134a every summer, but then it would work all summer. The POS did finally croak due to an unrelated problem. Having said all that, notice when I recharged my 1990 vette, I did go with the R12 for $389.

 

Is R12 that expensive because of environmental issues or is the price that high because of Dupont production costs? I live in Sweden, I have not checked how things are here, but I will.

 

Another quick question. There is no special on/off-switch for just the AC, it should go on automatically, when inside temp is above the set value?

 

This is from my 86, but may provide some help.
http://members.shaw.ca/dankai/AC%20Electronic.pdf

 

1. Jumper across the low pressure switch to see if your cluch is faulty. If cluch works, your probably low on freon.
2. Goto Diagnostic test below (Since it's so long I put it on the bottom)
3. Buy the DVD at Autozone. Cost $6.99 UPC code 0 52948 64101 2 It will tell you everything you need. It's call Diagnosing and Repairing Air Conditioning Systems with Bruce Bonebrake (Part number ACV101)
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1990-1996: HVAC Diagnostic Codes
On 1990 to 1996 Corvettes equipped with RPO C68 (electronic climate control), it is possible to read the HVAC system diagnostic codes from the climate control panel on the dashboard.

1. To enter the diagnostic mode, press the fan up and down arrow buttons at the same time until -00 appears on the digital readout.

2. One you have entered the diagnostic mode, you can scroll through the various parameters by using the up and down fan buttons.

3. To view the value for a particular parameter, press the "AUTO" fan button. Note: If you see a "-" next to a parameter value (example: "-105"), you must add "100" to that value to obtain the correct value for that parameter. Therefore, the correct reading would be 205 for this example.Parameter Description
Values 0 System Faults(one of these will be set if your air conditioning controls have an LED flashing)
00=No Faults
01= Temp Door Motor Circuit Fault
02= Temp Door Motor Circuit Fault
03 = Ambient Sensor Open
04 = Ambient Sensor Short
05 = In-Vehicle Temp Sensor Open
06 = In-Vehicle Temp Sensor Short
07 = Solar Load Sensor Open
08 = Solar Load Sensor Short09 = Low Freon Detected10 = UART Failure

1 Temp Setting 60F to 90F
2 In-Car Temp Sensor 10 = HOT -130 = 230 = COLD
3 Outside Temp Sensor 10 = HOT -130 = 230 = COLD
4 Sun Load Sensor Max light Max DarkL98 38 183LT5 115 -110 = 210
5 Ignition System Voltage 0 = 9 Volts -155 = 255 = 16 V
6 Engine Speed (RPM divided by 25)
7 Vehicle Speed
9 A/C System Mode 00 = OFF01 = Re-Circulation02 = A/C03 = Bi-Level04 = Heater06 = Defrost07 = Vent10 = Manual Re-Circulation
10 Blower PWM 0 = 0 Volts 128 = 14 Volts
11 Program Number 00 = COLD -155 = 255 = HOT
12 Mix Number -155 = 255 = COLD 00 = COLD
16 Coolant Temperature In degrees C
17 Solar Correction 114 = Max light 128 = max dark
30 Stored Full Hot Value 0 to 50
31 Temp Door Travel Range 100 to 200
34 Temp Door Position Requested 00=Full HOT -153=253=Full COLD
35 Compressor On Time 0.1 second increments
36 Number Of Times Below Critical Time
37 Software Version Number

 

Finding something at AutoZone wil be pretty difficult for ghd as he lives in Sweden

The diagnostic procedure is the one to follow and it sounds like he has the C68 Electronic Climate Control system in the car. If the BCM has decected a problem in the system, the green indicator light above the "Auto" button should be flashing.

The most common problem is loss of refrigerant. If this is the case, the compressor should be cycling on and off every few seconds with the A/C turned on.

Not knowing what the laws are in Sweden regarding the retail sale of refrigerant or what refrigerant must be used in vehicles, the best thing I would suggest is to go to a reputable shop and have the system pressures tested. If the system is low on refrigerant, it can be recharged and a dye added to be able to check for leaks under ultra-violet light.

The system can be converted to R134-a fairly easily but it is something that should be done by a shop that has the necessary A/C equipment to completely remove any R-12, and properly install the new refrigerant with the correct oil and any other components.