A/c recharge
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Teching In
Joined: Jul 2007
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A/c recharge been a long time since here last.still say this is one of the most informative boards. anyway 1999 trans am 5.7 litre , how do i recharge the system?? GM manual is no help. basically not sure where to attach the refrigerant bottle. i see 2 dustcaps both black 1 on the silver canister (accumulator i believe) which sits just rear of the battery, and the other cap is leading to what looks like the condenser, just betweeen battery and radiator. Or is there another location i can't see? Thanks for a response
ken
ken
You have two connections into your AC circuit. One is on the high side and the other on the low side. I can't remember which ones they are but they are 2 different sizes. In this case if it doesn't fit, don't force it in.
Buying a bottle of refrigerant from autozone is a waste of money. You have no idea how much refrigerant you are actually putting into the system. Overcharging is just as bad a undercharging.
The best way to do it is with an AC machine. Recover the system and make note of how much refrigerant is recovered and how much PAG oil is removed. Pull a vacuum to ensure that you have recovered all of the refrigerant (and if you have been injecting cans in it to make sure you get all of the moisture and air out) and then recharge it with the specified amount of R-134A and inject the amount of PAG oil back into the system that was removed during recovery.
Why do you want to recharge the system?
Buying a bottle of refrigerant from autozone is a waste of money. You have no idea how much refrigerant you are actually putting into the system. Overcharging is just as bad a undercharging.
The best way to do it is with an AC machine. Recover the system and make note of how much refrigerant is recovered and how much PAG oil is removed. Pull a vacuum to ensure that you have recovered all of the refrigerant (and if you have been injecting cans in it to make sure you get all of the moisture and air out) and then recharge it with the specified amount of R-134A and inject the amount of PAG oil back into the system that was removed during recovery.
Why do you want to recharge the system?
The one between the compressor and the condenser
is the high side port and the one between evaporator
(air box) and condenser is low side. If you fill from the
low side you must fill with vapor, not liquid, to avoid
slugging the compressor. You can't fill via the high side
unless the system is flat, running pressure is too high.
The system has some excess capacity and you can
fill until the low side pressure gets into the good zone
on your gauge set, just don't go over. If you're so low
that the low pressure switch is cutting out, that'll take
a full can.
I do recommend biting the bullet and getting a manifold
gauge set, you can tell a lot about what's up with that
and most can-tappers will mate up or adapt up to the
center line.
If your charge slows down a bucket of warm water to
float the can in, will help.
If you've taken years to lose charge and see no sign
of serious oil weep at the compressor, you probably
do not need oil. One can of "oil charge" might not
hurt anything; certainly I've done that plenty of times,
several per beater over the decades, with no evident
downside. Oil charge with dye, would let you see if
any seal weep is going on (UV lamp sold separately).
If you lose charge in less than a year then you have
to think about saving the planet. If it's just once a
decade top-off, then just top it off and the baby
seals are on their own. If you've got zero pressure
then you have to consider that more may be wrong.
is the high side port and the one between evaporator
(air box) and condenser is low side. If you fill from the
low side you must fill with vapor, not liquid, to avoid
slugging the compressor. You can't fill via the high side
unless the system is flat, running pressure is too high.
The system has some excess capacity and you can
fill until the low side pressure gets into the good zone
on your gauge set, just don't go over. If you're so low
that the low pressure switch is cutting out, that'll take
a full can.
I do recommend biting the bullet and getting a manifold
gauge set, you can tell a lot about what's up with that
and most can-tappers will mate up or adapt up to the
center line.
If your charge slows down a bucket of warm water to
float the can in, will help.
If you've taken years to lose charge and see no sign
of serious oil weep at the compressor, you probably
do not need oil. One can of "oil charge" might not
hurt anything; certainly I've done that plenty of times,
several per beater over the decades, with no evident
downside. Oil charge with dye, would let you see if
any seal weep is going on (UV lamp sold separately).
If you lose charge in less than a year then you have
to think about saving the planet. If it's just once a
decade top-off, then just top it off and the baby
seals are on their own. If you've got zero pressure
then you have to consider that more may be wrong.
A/C doesnt consume refigerant ever. If your system doesnt have any refrigerant then its leaking. Putting anything into it will 100% leak right back out, how fast depends on the leak.
Get it fixed the right way, find and repair the leak, recover the refrigerant, evacuate the system, then recharge correctly.
Get it fixed the right way, find and repair the leak, recover the refrigerant, evacuate the system, then recharge correctly.
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i just performed a repair on my system
it was leaking out of the valve on the drier can
i replaced the valve and vaccumed down the system
added the oil
tried added the freon
the compressor is kicking howeve the air does NOT get cold at all
i also replaced the orfice (spelling) tube while i had the system opened up, it was filled with metal shavings so im glad i did it but like i said im getting zero for cold air, the drier canister isnt even getting frosty like it should with the ac running
any ideas?
it was leaking out of the valve on the drier can
i replaced the valve and vaccumed down the system
added the oil
tried added the freon
the compressor is kicking howeve the air does NOT get cold at all
i also replaced the orfice (spelling) tube while i had the system opened up, it was filled with metal shavings so im glad i did it but like i said im getting zero for cold air, the drier canister isnt even getting frosty like it should with the ac running
any ideas?
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On The Tree
Joined: Dec 2005
Posts: 111
Likes: 0
i just performed a repair on my system
it was leaking out of the valve on the drier can
i replaced the valve and vaccumed down the system
added the oil
tried added the freon
the compressor is kicking howeve the air does NOT get cold at all
i also replaced the orfice (spelling) tube while i had the system opened up, it was filled with metal shavings so im glad i did it but like i said im getting zero for cold air, the drier canister isnt even getting frosty like it should with the ac running
any ideas?
it was leaking out of the valve on the drier can
i replaced the valve and vaccumed down the system
added the oil
tried added the freon
the compressor is kicking howeve the air does NOT get cold at all
i also replaced the orfice (spelling) tube while i had the system opened up, it was filled with metal shavings so im glad i did it but like i said im getting zero for cold air, the drier canister isnt even getting frosty like it should with the ac running
any ideas?
General rule of thumb, any time you open up the A/C system you always need to replace the oarfice tube and the complete dryer; treat them both as serviceable parts. Its also a very good idea to take out the condensor and evaporator and clean them out with some chemical flush/ compressed air.
Seing as how you have metal shavings, your compressor is toast. At the very least you need to replace the oarfice tube, dryer, compressor; and while you could try to flush out the condensor and evaporator, I would just go ahead and replace them. Any metal shavings left in the system are just going to grenade any new parts you put on there. I'd go ahead and replace any pressure switches as preventative maintenance.
A good piece of advice for anyone charging/recharging their A/C, DO NOT use those cheap **** cans with stop leak or 'high mileage seal conditioner'. They act like liquid glue and will f&*! your system up. I personally try to only use the Dupont 134A, and would only use ONE single can that has the UV dye mixed in. The store brand 134A should be good enough, just don't get the stuff with anything besides the UV dye mixed in.
Launching!
Joined: Feb 2007
Posts: 219
Likes: 0
From: slodeatha tx
my ac just quit blowing cold air. it has enuff coolent but the air that comes in is the same temp as the vent air. i can hear the condenser kick in but still nothing. can anyone help me with what might be wrong
Some one might have already said this, but if there is air in you A/C lines, you need to draw a good vacuum on it for about an hour before any refrigerant goes in. You can't just plug a bottle of R-134a in you bought from autozone.
not on our cars. the smaller fitting is the low side, the larger is the high side.
my ac just quit blowing cold air. it has enuff coolent but the air that comes in is the same temp as the vent air. i can hear the condenser kick in but still nothing. can anyone help me with what might be wrong
my ac just quit blowing cold air. it has enuff coolent but the air that comes in is the same temp as the vent air. i can hear the condenser kick in but still nothing. can anyone help me with what might be wrong
Check to see that your compressor is compressing. You need a set of gauges for this (cheap at harbor freight). The high side should put out ~250 psi and the low side should put out ~40 psi while the motor is idling.
Launching!
Joined: Feb 2007
Posts: 219
Likes: 0
From: slodeatha tx
The can of stuff i bought has a gauge on it and im just going by what it said. when i first put it on there it read about 100 psi, but from what i could find that was to much. so i let some out then put more back in. the results didnt change. it still blew the same old air it was. when it comes to ac i dont know ****. i do know that when going on trips it would blow softer and softer, i would run the vent for a wial then it would go back to normal. i just figured it was frezzing up
100 psi while the motor was running? It's important to know what the high side is doing too, not just the low side. If the high side is also at 100 psi while the motor is running and your compressor is engauged, your compressor isn't compressing anything.
Also, you plugged into the low side, right? (The smaller fitting on the dryer)
Also, you plugged into the low side, right? (The smaller fitting on the dryer)
TECH Addict
Joined: Jun 2009
Posts: 2,012
Likes: 0
From: Tulsa, OK
The smaller fitting, on the dryer, is the low pressure side and the larger fitting, next to the condenser, is the high side.
It is this way on all R-134a vehicles. Not sure about older r-12 systems.
TECH Addict
Joined: Jun 2009
Posts: 2,012
Likes: 0
From: Tulsa, OK
The low side fitting is smaller than the high side. I just went and looked to double check.
The smaller fitting, on the dryer, is the low pressure side and the larger fitting, next to the condenser, is the high side.
It is this way on all R-134a vehicles. Not sure about older r-12 systems.
The smaller fitting, on the dryer, is the low pressure side and the larger fitting, next to the condenser, is the high side.
It is this way on all R-134a vehicles. Not sure about older r-12 systems.
R12 fittings were both the same size. Same as the Shrader in tires.
Last edited by fleetmgr; Sep 23, 2009 at 11:05 PM.
Launching!
Joined: Feb 2007
Posts: 219
Likes: 0
From: slodeatha tx
100 psi while the motor was running? It's important to know what the high side is doing too, not just the low side. If the high side is also at 100 psi while the motor is running and your compressor is engauged, your compressor isn't compressing anything.
Also, you plugged into the low side, right? (The smaller fitting on the dryer)
Also, you plugged into the low side, right? (The smaller fitting on the dryer)
The high side should be ~250 psi. If your low side is at 100 psi, the car is running and your compressor is engaged, It sounds like your compressor is done. The pressures on each side are probably equalized, which means no compression is taking place.
