Need help from the Testarossa gurus: I've some trouble with my AC as there is a poor cooling. I flushed the system of the old R12 and tried to fill the system with duracool. But I'm not able to fill the system as on the low pressure side I could read 73 PSI and on the High pressure side only 55 ! I've checked the compressor clutch and it is able to engage, also the condenser fan is working. What could I try now ? Thank you Louis
Louis Those pressure numbers would be hard to reconcile with what a compressor is designed to do. The small line will be the discharge/high pressure side of the compressor and the large line will be the low pressure/suction side. If the discharge pressure is lower than than the suction pressure something is seriously wrong with the compressor-compressor valves. If the compressor can not pump at least 200 psi on the discharge line you probably have a bad compressor. If the expansion valve was stuck wide open the suction pressure would be much higher, too. If the system was open to the atmosphere for a while and got full of air, you work need to use a vacuum pump to remove the air from the system before you add new refrigerant. Air would typically make the pressures higher, but you would get any cooling. Good luck, Jerry DRG
If your gauges are accurate you have a severe blockage. Even with the compressor not working you should have equal pressure on both sides. My car had the desicant bag fall apart (from the dryer) and clogged the system at the expansion valve. I got lucky, as I was able to reverse flush the system to get the debris out. I don't know what the duracool is but I use R134a and it works fine
Thank you for all the input. I'll try to flush the system with Diversitech Pro Flush Kit... But I don't understand how the pressure on the suction side could be higher than on the discharge side ???
I would double check your gauge accuracy. A system which is not in operation should have equal pressure on both sides
Just a reminder to replace the receiver/dryer after the flush (especially if it was the cause of the debris)
Also make sure to do a long vacuum to evaporate as much humidity as possible if the system has been non working for a while. I just refreshed my system with R-134 and it is VERY cold. Also, I would never use DURACOOL. It is an hydrocarbon. I would feel very unsafe having this in my system in case of a leak Inside the cab. I'm not sure it is legal to use it in cars.
What your stating makes no sense. Your high pressure is lower than the low. I have to believe that you have your gauges backwards. When you try to add coolant does it to in? If you are on the high side it is about impossible to get it to go in. Try reversing your intake point and see if the "high side" takes the coolant. It is odd though that that side is 55 which is still high and should be full. I'd try another set of gauges. Buy one of the cans that comes with one. That way you can at least verify your numbers and you haven't wasted much money because you can use the coolant. I just flushed my system, new drier, and coolant and the A/C is excellent. The car gets cold enough in direct sunlight to have to cut the temperature back. The air coming out of the side vents is poor but they all are. Don't let the others on this site tell you that the A/C is poor on these cars. If you do it right the TR with 134A is about as good as most modern cars.
I agree with you and don't understand how I could read these numbers ! but the suction and discharge ports are labelled on the compressor... anyway I'll try to fill by the high pressure port. Also, I tried with a gauge that came with a can of coolant and the pressure reach the "red" warning zone immediately. AC was working well before major but the mechanic let the system empty after service because he was not able to found R12 in France and I think that the AC suffered from this period in contact with air. Also the dryer bottle was from 1993, of course I've removed it and changed to a newer unit. It seems that if the expansion valve is stuck open, these pressure numbers could be read...
ES12 and duracool are very simar if not the same. It's flammability requires very high compression in order to ignite, unlike gasoline. I've installed es12 in 4 cars now and it's been phenomenal stuff. I feel more uncomfortable about the larger fuel tanks and multiple fuel lines around a hot engine than I do with es12.
Have you looked for any refrigerant flow at the observation window on the Dryer? I'd lean towards blockage as suggested before (if you've got the gauges hooked up correctly and the various valves on the gauge assembly set correctly )...
Yes, I could see some bubbles as I'm able to fill the system up to the point that pressure in the system is equal to the pressure in the can, but the compressor is not able to decrease the pressure in the low side...
Some news after some work on the ac system - I flushed the lines with solvent and air pressure. From the dryer to the suction port, the line was free. From the Discharge port to the dryer, it was not possible to apply a pressure above 4 bars to the line, but the pressurized air could flow up to the dryer - I changed the AC compressor by a brand new one. The pressure measurements are almost the same after removal of the old compressor: when the compressor engage, the low side rise up to 5 bars and the high side is 4.5 bars. With the compressor not engaged, the pressure are equal between low and high side. - The Condenser fan is not working anymore. The fan motor is OK (I plugged directly a 12 V battery to the fan); I've no more +12 V at the input side (before the removal of the compressor, I had !) and I've no +12V on the C4 terminal on the fuse board. I totally puzzled with this system ! What could I investigate anymore ? Louis
