Air Conditioner Test
There has been a lot of posts on this site about AC performance. You see a lot of people saying that you can only expect a 20 degree drop in temperature from your AC. I'm not sure how this story got s...
Forum Discussion
I had to work on my car Air Conditioner today and did some more tests. I realize these test prove nothing and that they have nothing to do with RV's.
My car is a 1984 Lincoln Mark VII. It originally had R-12 as a refrigerant but, you can no longer get that. Some years ago it was converted over to using R-134 for a refrigerant. The conversion was not done in the best possible way. The mechanic simply evacuated the system of refrigerant and oil, installed a new line dryer in the suction line and , refilled the system with R-134.
He actually put more ounces of R-134 in then what the system called for using R-12. A few months later while driving in stop and go traffic the high side pressure got to high, a check valve opened and some refrigerant bled off. The system worked better after that.
I have a slow leak in the system and every 5-7 years I have to add some more R-134. I did that today. According to the cheap gauge and refill system I bought at the local discount store the low side pressure in this system should be between 25 and 45 PSI. From experience I have found that the system works best when I stay to the low side of that range so I added refrigerant until the pressure read 25 PSI. I then shut the car off and let everything warm back up for about 3 hours to outside temps.
It was 90 degrees f when I started the test at 5:00 PM. I put a temperature probe in duct on the dash. At 5:02 the temp of air coming out of the duct had fallen to 62 degrees. At 5:03 it was 55. At 5:04 it was 48. At 5:05 it was 45. At 5:06 it was 42. At 5:07 it was 37 degrees. But,,,, as someone is sure to point out I had the car running on recirculation mode and it was cooling off inside the car. At 5:08 the temp of the air coming out of the duct was 35 degrees. I let it run for another 10 minutes and it never got any colder then that.
I also have for my primary vehicle a 2004 Chevy 1500 pickup. I did a test on it too. It also uses R-134 for a refrigerant. For some reason when I checked the low side pressure on the truck it read 50 PSI. That is higher then I thought it should be but, this system has never been touched and that is how it was designed by the factory.
It was 90 degrees when I started the test at 1:46. I also had the system on recirculate. At 1:47 the temp at the duct had fallen to 70 degrees. At 1:49 it was 66. At 1:51 it was 66. At 2:00 it was 65. I kept a eye on the temp coming out of the duct for the next 10 minutes and it never fell below 65.
Once again this proves, or means, nothing. These are just some observations I made today.
Have a nice Day
My car is a 1984 Lincoln Mark VII. It originally had R-12 as a refrigerant but, you can no longer get that. Some years ago it was converted over to using R-134 for a refrigerant. The conversion was not done in the best possible way. The mechanic simply evacuated the system of refrigerant and oil, installed a new line dryer in the suction line and , refilled the system with R-134.
He actually put more ounces of R-134 in then what the system called for using R-12. A few months later while driving in stop and go traffic the high side pressure got to high, a check valve opened and some refrigerant bled off. The system worked better after that.
I have a slow leak in the system and every 5-7 years I have to add some more R-134. I did that today. According to the cheap gauge and refill system I bought at the local discount store the low side pressure in this system should be between 25 and 45 PSI. From experience I have found that the system works best when I stay to the low side of that range so I added refrigerant until the pressure read 25 PSI. I then shut the car off and let everything warm back up for about 3 hours to outside temps.
It was 90 degrees f when I started the test at 5:00 PM. I put a temperature probe in duct on the dash. At 5:02 the temp of air coming out of the duct had fallen to 62 degrees. At 5:03 it was 55. At 5:04 it was 48. At 5:05 it was 45. At 5:06 it was 42. At 5:07 it was 37 degrees. But,,,, as someone is sure to point out I had the car running on recirculation mode and it was cooling off inside the car. At 5:08 the temp of the air coming out of the duct was 35 degrees. I let it run for another 10 minutes and it never got any colder then that.
I also have for my primary vehicle a 2004 Chevy 1500 pickup. I did a test on it too. It also uses R-134 for a refrigerant. For some reason when I checked the low side pressure on the truck it read 50 PSI. That is higher then I thought it should be but, this system has never been touched and that is how it was designed by the factory.
It was 90 degrees when I started the test at 1:46. I also had the system on recirculate. At 1:47 the temp at the duct had fallen to 70 degrees. At 1:49 it was 66. At 1:51 it was 66. At 2:00 it was 65. I kept a eye on the temp coming out of the duct for the next 10 minutes and it never fell below 65.
Once again this proves, or means, nothing. These are just some observations I made today.
Have a nice Day
