FluX On: Air Conditioning Part 3 - Recharging - DISCUSSION
#1
03-13-2008, 03:42 PM
FluX On: Air Conditioning Part 3 - Recharging - DISCUSSION
To recharge an air condioning system you need the proper set of tools.
You need to start off with a set of R-134a gauges. These run about $40-$200 depending on the build quality and who is selling them.
Then you need a vacuum pump. Higher vaccuum is better opposed to higher flow. A DVD I saw from Autozone claims they have them for rent, but I have never been able to find one at any Autozone I have been in. The venturi type pumps are crap and require a monster compressor to supply the 90PSI at 4CFM required for 30 minutes.
A 1.5CFM single stage pump that can achieve 50u of vaccuum is About $135 at http://www.ackits.com/. Don't forget to get some extra deep vane vacuum pump oil, this pump takes 5 ounces.
You will need 1.9 - 2.0 pounds of R-134a which is approximently 3 cans worth. It doesn't matter who made it. The price of R-134 seems to go up in the summer so you should stockpile some in the winter.
If completely recharging the system you may wish to get a can with a UV shot for future diagnoses. I would go with 2 cans of EF Products 301 R-134a and a can of 307 R-134a plus which has the UV shot, O-Ring conditioner and Oil Charge. You will also need a can tap for the R-134a, EF Products 421.
While at Autozone, consult the Hanyes book on the shelf entitled Automotive Heating & Air Conditioning. From the tables look up the fill capacity of your vehicle and memorize them.
For a 99 Blazer it is:
PAG
(V-7 Compressor) 9 oz.
(HT6 Compressor) 8 oz.
R-134a
(Manual Controls) 1.9 lb.
(Automatic Controls) 2.0 lb.
If you flushed the system you will need to add all of the proper type of PAG to the compressor and dryer before reassembly. Compressors can not be flushed so all the oil must be first drained if reusing one. Don't forget to include the amount that is in any of the cans of refridgerant to your measurements. Put half in the compressor and half in the dryer.
Using a 13mm socket, rotate the compressor clockwise to circulate the oil. Do this for about 10 revolutions.
Attach the hose set to both the low side and the high side ports. These will only go on one way. Once on you will need to open the schrader valves, depends on the gauge set, on mine I turn the ***** that are now on the service ports clock wise to push in.
On the gauge set open both sides to the service port by opening both *****. Once done connect the service line (yellow) to the vacuum pump and switch on. Be sure to open the vacuum pumps vent. The needles should start going negitave and rest as low as they can go, typically -30, Took about 20 seconds for me. Leave the setup to run for 30 minutes.
Before turning off the pump close both the ***** on the gauge set to off. Disconnect the pump. Note the gauge reading and come back in 30 minutes and see if it changed. If it did you have a leak. See if you can hear the hissing to pinpoint it. Do not remove the high or low side hoses from the system as when vacuum is present the scharder valves leak inwards.
If satisfied there are no leaks screw the tap to the first can of R-134a. Be sure the piercing probe is retracted first. Connect to the service hose and pierce the can. Purge the hose by pressing the schrader valve on the gague set. Warning: This will release R-134 in its liquid state. Use a tool while wearing some gloves and have the gauges facing away from you first.
Once purged open both high side and low side valves to allow gas to enter system. Shake the can and notice the sight glass on the gauge set. This is useful in determining when the can is empty. Once the presure has stabilized close the high side valve on the gauges.
Start the car and turn the A/C on MAX and high speed on the fan. Note that the compressor will only run 5 seconds at a time until there is enough gas in the system. Shake the can while holding upside down to give gas in liquid state. Some people like to hold the can upright so it is gas only, others do half and half. Watch the sight glass until it 'empties'.
When you are sure there is no more gas in the can, close the low side valve and tap another can of R-134a and repeat the process. Leave the low side valve closed when out of refridgerant.
As you are filling, the high side gauge should rise while the low side stays between the same range while cycling. When there is enough gas the length of the cycling will change and eventually the compressor will stay engauged until it gets too cold and then start cycling again.
With the compressor running the system gauge set will indicate around 25-50 PSI on the low side and 150-200 PSI on the high side. These numbers vary with tempreture.
Kill the engine and wait for both gauges to equalize. For me this was in the 55 PSI range. Pop off the quick disconnects from the service ports without retracting the ***** that hold the scrader valves open. That way the presure improves the seating and the seal of the valves.
Check for leaks as outlined in 'FluX On: Air Conditioning Part 2 - Slow Leaks'.
You need to start off with a set of R-134a gauges. These run about $40-$200 depending on the build quality and who is selling them.
Then you need a vacuum pump. Higher vaccuum is better opposed to higher flow. A DVD I saw from Autozone claims they have them for rent, but I have never been able to find one at any Autozone I have been in. The venturi type pumps are crap and require a monster compressor to supply the 90PSI at 4CFM required for 30 minutes.
A 1.5CFM single stage pump that can achieve 50u of vaccuum is About $135 at http://www.ackits.com/. Don't forget to get some extra deep vane vacuum pump oil, this pump takes 5 ounces.
You will need 1.9 - 2.0 pounds of R-134a which is approximently 3 cans worth. It doesn't matter who made it. The price of R-134 seems to go up in the summer so you should stockpile some in the winter.
If completely recharging the system you may wish to get a can with a UV shot for future diagnoses. I would go with 2 cans of EF Products 301 R-134a and a can of 307 R-134a plus which has the UV shot, O-Ring conditioner and Oil Charge. You will also need a can tap for the R-134a, EF Products 421.
While at Autozone, consult the Hanyes book on the shelf entitled Automotive Heating & Air Conditioning. From the tables look up the fill capacity of your vehicle and memorize them.
For a 99 Blazer it is:
PAG
(V-7 Compressor) 9 oz.
(HT6 Compressor) 8 oz.
R-134a
(Manual Controls) 1.9 lb.
(Automatic Controls) 2.0 lb.
If you flushed the system you will need to add all of the proper type of PAG to the compressor and dryer before reassembly. Compressors can not be flushed so all the oil must be first drained if reusing one. Don't forget to include the amount that is in any of the cans of refridgerant to your measurements. Put half in the compressor and half in the dryer.
Using a 13mm socket, rotate the compressor clockwise to circulate the oil. Do this for about 10 revolutions.
Attach the hose set to both the low side and the high side ports. These will only go on one way. Once on you will need to open the schrader valves, depends on the gauge set, on mine I turn the ***** that are now on the service ports clock wise to push in.
On the gauge set open both sides to the service port by opening both *****. Once done connect the service line (yellow) to the vacuum pump and switch on. Be sure to open the vacuum pumps vent. The needles should start going negitave and rest as low as they can go, typically -30, Took about 20 seconds for me. Leave the setup to run for 30 minutes.
Before turning off the pump close both the ***** on the gauge set to off. Disconnect the pump. Note the gauge reading and come back in 30 minutes and see if it changed. If it did you have a leak. See if you can hear the hissing to pinpoint it. Do not remove the high or low side hoses from the system as when vacuum is present the scharder valves leak inwards.
If satisfied there are no leaks screw the tap to the first can of R-134a. Be sure the piercing probe is retracted first. Connect to the service hose and pierce the can. Purge the hose by pressing the schrader valve on the gague set. Warning: This will release R-134 in its liquid state. Use a tool while wearing some gloves and have the gauges facing away from you first.
Once purged open both high side and low side valves to allow gas to enter system. Shake the can and notice the sight glass on the gauge set. This is useful in determining when the can is empty. Once the presure has stabilized close the high side valve on the gauges.
Start the car and turn the A/C on MAX and high speed on the fan. Note that the compressor will only run 5 seconds at a time until there is enough gas in the system. Shake the can while holding upside down to give gas in liquid state. Some people like to hold the can upright so it is gas only, others do half and half. Watch the sight glass until it 'empties'.
When you are sure there is no more gas in the can, close the low side valve and tap another can of R-134a and repeat the process. Leave the low side valve closed when out of refridgerant.
As you are filling, the high side gauge should rise while the low side stays between the same range while cycling. When there is enough gas the length of the cycling will change and eventually the compressor will stay engauged until it gets too cold and then start cycling again.
With the compressor running the system gauge set will indicate around 25-50 PSI on the low side and 150-200 PSI on the high side. These numbers vary with tempreture.
Kill the engine and wait for both gauges to equalize. For me this was in the 55 PSI range. Pop off the quick disconnects from the service ports without retracting the ***** that hold the scrader valves open. That way the presure improves the seating and the seal of the valves.
Check for leaks as outlined in 'FluX On: Air Conditioning Part 2 - Slow Leaks'.
#2
05-16-2008, 09:20 PM
RE: FluX On: Air Conditioning Part 3 - Recharging - DISCUSSION
Guess I'll be the first....I just borrowed a loaner vacuum pump from the autozone by my house. They wanted a $200 deposit which will begiven backto me upon return of the vacuum and gauges. I have the pump running now and just tryin to kill some time. Great how-to...thanx! Oh yeah! I changed my compressor, accumulator, and orfice tube.
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