Air conditioning help
Thread Starter
Instructor
Joined: Aug 2010
Posts: 233
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From: Monrovia Md
Air conditioning help
1981 - Finally got around to fixing my AC after it has been empty for 27years. I pulled a vacuum on it for about an hour. After 30 minutes it was still holding a vacuum. So I added three 6 oz cans of Enviro- Safe. I decided to use this instead of converting to r134. The instructions say that each can is equivalent to 18 oz of r12
After the first can, the compressor clutch came on ( I admit I was happily surprised). I put in the other two cans, compressor cycled nicely. I used an oil tester and it read low on oil, so I added 3 oz of oil.
Problem, the air from the dash is 60 deg. I am pretty sure the heater is not on, temp from the vent setting is the same temp as outside air
Static pressure on both sides is 80 psi
Operating pressures when cycling
Low side 25-45 psi
High side 180- 215 psi
Ambient temperature is about 80 deg
Low side pipe to the compressor is cold to the touch ( seems much colder than 60 deg)
Seems like the compressor is working correctly. Any ideas why the temperature is so high?
After the first can, the compressor clutch came on ( I admit I was happily surprised). I put in the other two cans, compressor cycled nicely. I used an oil tester and it read low on oil, so I added 3 oz of oil.
Problem, the air from the dash is 60 deg. I am pretty sure the heater is not on, temp from the vent setting is the same temp as outside air
Static pressure on both sides is 80 psi
Operating pressures when cycling
Low side 25-45 psi
High side 180- 215 psi
Ambient temperature is about 80 deg
Low side pipe to the compressor is cold to the touch ( seems much colder than 60 deg)
Seems like the compressor is working correctly. Any ideas why the temperature is so high?
Last edited by wajulia; Jun 16, 2013 at 01:59 PM.
Thread Starter
Instructor
Joined: Aug 2010
Posts: 233
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From: Monrovia Md
If the markings on the can are correct that 6 oz of enviro-safe is equivalent to 18 oz of r12, I put an equivalent of 3.3 lbs in the system.
Melting Slicks
Joined: May 2002
Posts: 2,716
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From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
according to the conversion for R12 vs Enviro-Safe your a little over charged but your pressures indicate your low on charge.
The low pressure switch is set to shut the compressor off around 18 to 22 psi. If the clutch is cycling then their is something else wrong after putting in 3 6oz cans of Enviro-Safe.
I've used Enviro-Safe Industrial 12 and was impressed with the vent temps.
what are the pressure readings sitting in the driveway idling with the AC on?
Is the compressor cycling while idling?
Neal
The low pressure switch is set to shut the compressor off around 18 to 22 psi. If the clutch is cycling then their is something else wrong after putting in 3 6oz cans of Enviro-Safe.
I've used Enviro-Safe Industrial 12 and was impressed with the vent temps.
what are the pressure readings sitting in the driveway idling with the AC on?
Is the compressor cycling while idling?
Neal
Race Director
Joined: Mar 2006
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From: Florida
Don't know what the ambient temp is, but if your driving on a hot sunny day with a decent heat load and it is not in max mode (recirculating), then 60° isn't that bad a temp for an older car with for certain air leaks.
And before anyone says their temps are <40°, I could probably take this car and get it to read 38° without doing anything to the system.
And before anyone says their temps are <40°, I could probably take this car and get it to read 38° without doing anything to the system.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Could also be the evaporator has a bunch of trash on it. Again, airflow. Somehow all sorts of leaves, dirt, bugs, and paper finds it's way to the inside of the sir box.
Race Director
Joined: Sep 2001
Posts: 10,560
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From: Wellington, FL
St. Jude Donor '11 thru '25
I too would block off the heater. You can just take a pair of vice grips and squeeze one of the heater hoses for test purposes. Put something flat between the teeth to keep from damaging the hose. Another thing to check is the weather stripping at the rear of the hood. I believe the '81 came with one and if its missing or not sealing, hot air from the engine compartment will end up in your duct work raising a/c temps at the vents.
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From: Plano TX
The pressures look OK, maybe a bit low but I have no experience with the refrigerant you use.
On a 80F day I expect a C3 AC system to blow <50F out the vents @ idle.
Disconnecting/blocking the heater core is a good suggestion. Might be that your blend door is misaligned or leaking to where you always blow heated air out the vents.
Thread Starter
Instructor
Joined: Aug 2010
Posts: 233
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From: Monrovia Md
At idle low side about 35. High side around 220
I will try to check the evaporator
Melting Slicks
Joined: Mar 2009
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Please explain how the oil tester works. What type of oil did you put into the system? Envirosafe is a Hydrocarbon which means flammable as in Freeze12. Take that $h!t out and get some R-12. We sometimes make things harder than they need to be. If the compressor is not staying on all of the time until the interior gets to about 60 degrees then something is not right. You stated that the vent on cold is the same as ambient. Is this with a car up to operating temps.? If so, then you do not have a problem with the heater shut off valve or blend door. mike...
Last edited by mds3013; Jun 16, 2013 at 05:32 PM.
Le Mans Master
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Don't know what the ambient temp is, but if your driving on a hot sunny day with a decent heat load and it is not in max mode (recirculating), then 60° isn't that bad a temp for an older car with for certain air leaks.
And before anyone says their temps are <40°, I could probably take this car and get it to read 38° without doing anything to the system.
And before anyone says their temps are <40°, I could probably take this car and get it to read 38° without doing anything to the system.
Le Mans Master
Joined: Feb 2011
Posts: 5,943
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From: Southern NH
Thread Starter
Instructor
Joined: Aug 2010
Posts: 233
Likes: 18
From: Monrovia Md
Please explain how the oil tester works. What type of oil did you put into the system? Envirosafe is a Hydrocarbon which means flammable as in Freeze12. Take that $h!t out and get some R-12. We sometimes make things harder than they need to be. If the compressor is not staying on all of the time until the interior gets to about 60 degrees then something is not right. You stated that the vent on cold is the same as ambient. Is this with a car up to operating temps.? If so, then you do not have a problem with the heater shut off valve or blend door. mike...
I used the enviro-safe oil charge 3. Safe for r12 systems
Thread Starter
Instructor
Joined: Aug 2010
Posts: 233
Likes: 18
From: Monrovia Md
Please explain how the oil tester works. What type of oil did you put into the system? Envirosafe is a Hydrocarbon which means flammable as in Freeze12. Take that $h!t out and get some R-12. We sometimes make things harder than they need to be. If the compressor is not staying on all of the time until the interior gets to about 60 degrees then something is not right. You stated that the vent on cold is the same as ambient. Is this with a car up to operating temps.? If so, then you do not have a problem with the heater shut off valve or blend door. mike...
Last edited by wajulia; Jun 16, 2013 at 08:30 PM.
Race Director
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From: Florida
I'm sure mds3013 was concerned about the amount of oil. there is no way to test for that. take it apart and drain each component and refill is the only way. Too much oil will reduce the amount of cooling.
Race Director
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From: Florida
Here in S Florida, where the sun is brutal, the heat gain on a car in the open is amazing. Shoot a black dash with an IR gun that's been in the sunlite for awhile, even with the air on.
I can take a black car the has vent temps in the 50s or low 60s while driving and put it in the shade, windows rolled up, set on recirculate max, engine at >1500rpm and after about 15-20 minutes the center vent will be in the 30s. Wows people every time wondering why they can't get theirs that low.
Realistically, while driving, especially short distances, the vent temps will be close to 60.
How long does your house take to cool from 90 to 75. same thing.
Melting Slicks
Joined: Aug 2012
Posts: 3,487
Likes: 83
From: Titusville Florida
Don't know what the ambient temp is, but if your driving on a hot sunny day with a decent heat load and it is not in max mode (recirculating), then 60° isn't that bad a temp for an older car with for certain air leaks.
And before anyone says their temps are <40°, I could probably take this car and get it to read 38° without doing anything to the system.
And before anyone says their temps are <40°, I could probably take this car and get it to read 38° without doing anything to the system.
never mind, just saw the post above!
Last edited by AirborneSilva; Jun 17, 2013 at 11:09 AM.