A/C recharge how to?
#21
07-31-2010, 12:42 AM
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The screwdriver trick works really well. The hot ticket here would be to have a helper..... Stick the tip of the screwdriver on the compressor case, hold your ear against the handle. Have said friend turn on the A/C, if something happens, you will hear it. Guaranteed. 
You are looking for a change in the noise it is making.
Can you turn the center of the compressor pulley by hand?
You are looking for a change in the noise it is making.Can you turn the center of the compressor pulley by hand?
Last edited by exceldetail; 07-31-2010 at 03:08 PM.
#22
07-31-2010, 03:08 PM
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#23
07-31-2010, 04:09 PM
#24
07-31-2010, 07:48 PM
Rookie
Same as everyone above. I charged my system last week also. The compressor was cycling on then off every 10 - 15 seconds. When attached the pressure gauge the needle was surging from 15 to 55 psi. When I continued to charge it settled to an even 50psi. Remember it was 50psi for me because it was 90 here so make sure you check the can.
#25
07-31-2010, 08:48 PM
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#26
07-31-2010, 09:07 PM
when the compressor is running, the output pipe between compressor and evaporator will be the high pressure side, and will read something like 200-250 psi. this is the high pressure side. meanwhile, the input pipe between the evap and the compressor is the low pressure side. this is where you measure pressure and add refrigerant. it will read something like 20-40 psi.
when the compressor is not running, then the two sides equalize, and you can't do anything.
so, you have to get the compressor running one way or the other. to override the low pressure limit switch, you have to jumper the switch at the accumulator (black cannister thing). you also have to have 12v at the compressor, and the clutch has to work.
so - is your compressor turning or not ?
when the compressor is not running, then the two sides equalize, and you can't do anything.
so, you have to get the compressor running one way or the other. to override the low pressure limit switch, you have to jumper the switch at the accumulator (black cannister thing). you also have to have 12v at the compressor, and the clutch has to work.
so - is your compressor turning or not ?
#27
07-31-2010, 11:57 PM
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Wow, now theres a handful!
With the A/C on Max, the compressor never kicks in, although there is a slight difference in RPM's. I can turn the pulley by hand. I think I read somewhere that that was bad....?
In regards to the pressure reading, the refill kit I purchased with included hose and gauge only fits one connection. I assumed I was doing the right thing, i even checked both fittings. The one I fit it to is closest to the firewall, and small black canned accumulator (I assume).
With the A/C on Max, the compressor never kicks in, although there is a slight difference in RPM's. I can turn the pulley by hand. I think I read somewhere that that was bad....?
In regards to the pressure reading, the refill kit I purchased with included hose and gauge only fits one connection. I assumed I was doing the right thing, i even checked both fittings. The one I fit it to is closest to the firewall, and small black canned accumulator (I assume).
#28
08-01-2010, 12:19 PM
#29
08-01-2010, 01:04 PM
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#30
08-01-2010, 01:14 PM
Legend
Most kits are made to only fit only the low pressure port, DO NOT ATTEMPT TO FILL THE HIGH PRESSURE PORT!!!!
This would be bad. Know the correct port before you attempt to fill. I believe the caps have "L" and "H" stamped in them and do not interchange. Newer systems have a blue low cap and red high cap.
The RPM's change when you turn the a/c switch on as the PCM expects the RPMs to bog when the a/c compressor clutch engages. The PCM tells the IAC valve to retract a certain amount to compensate for the bogging and the driver never notices. You are noticing because your clutch is not engaging.
A severely overcharged system will not engage the clutch as the compressor will create a dangerous high side pressure. There is a blow off valve for a moderately overcharged system that sounds like heavy machine gun fire (ask me how I know
), but it is disabled in a highly overcharged system as even firing the compressor for a instant could blow the line. You DO NOT want to disable this safety feature with a jumper!
A severely undercharged system will also keep the clutch from engaging. In this instance, the jumper in the clutch relay must be employed to charge the system up.
If you have not added any R-134a and you have not had the A/C system serviced, you can reasonably assume you are too low on coolant and engage the clutch via the jumper.
If you have added a can or two and the clutch won't engage, the safest route is to assume it's too full, vent the system at slow increments to see if the clutch engages, and then add to the correct charge level if necessary. If the clutch begins to engage, you are probably in the moderately overcharged range and brace yourself for a fire fight when the blow off valve engages. Don't be under the hood when this happens because your liable to hit your head on the roof or get your hand caught somewhere bad. It's loud, and will scare the **** out of you. Do not vent the system completely empty, as you do not want to introduce outside air into the system. That will saturate your dryer/accumulator with moisture and you'll have to replace the accumulator and pull a vacuum on the system for 30 mins before recharging.
This would be bad. Know the correct port before you attempt to fill. I believe the caps have "L" and "H" stamped in them and do not interchange. Newer systems have a blue low cap and red high cap.
The RPM's change when you turn the a/c switch on as the PCM expects the RPMs to bog when the a/c compressor clutch engages. The PCM tells the IAC valve to retract a certain amount to compensate for the bogging and the driver never notices. You are noticing because your clutch is not engaging.
A severely overcharged system will not engage the clutch as the compressor will create a dangerous high side pressure. There is a blow off valve for a moderately overcharged system that sounds like heavy machine gun fire (ask me how I know
), but it is disabled in a highly overcharged system as even firing the compressor for a instant could blow the line. You DO NOT want to disable this safety feature with a jumper!A severely undercharged system will also keep the clutch from engaging. In this instance, the jumper in the clutch relay must be employed to charge the system up.
If you have not added any R-134a and you have not had the A/C system serviced, you can reasonably assume you are too low on coolant and engage the clutch via the jumper.
If you have added a can or two and the clutch won't engage, the safest route is to assume it's too full, vent the system at slow increments to see if the clutch engages, and then add to the correct charge level if necessary. If the clutch begins to engage, you are probably in the moderately overcharged range and brace yourself for a fire fight when the blow off valve engages. Don't be under the hood when this happens because your liable to hit your head on the roof or get your hand caught somewhere bad. It's loud, and will scare the **** out of you. Do not vent the system completely empty, as you do not want to introduce outside air into the system. That will saturate your dryer/accumulator with moisture and you'll have to replace the accumulator and pull a vacuum on the system for 30 mins before recharging.