Hi guys,
Does anyone know what the high/low side pressures should be on our A/C systems? and would the pressures be different for r12/r134?
A/C system pressures
-
t.mcginley.jr
- Posts: 1547
- Joined: Fri Jun 01, 2012 5:50 am
- Car: 2002 Nissan Altima SE 3.5
1990 Nissan 300ZX NA 2+0
1966 Ford Mustang - Location: New Jersey, USA
-
nissanfreak12
- Posts: 1709
- Joined: Sun Jan 23, 2011 4:07 pm
- Car: 92 300zx 2+2 TT
- Location: Denver, CO
Re: A/C system pressures
This is a good chart to go off of...
https://www.google.com/url?sa=t&rct=j&q ... 5608,d.aWc
134a runs 2psi lower than r-12 equivilant on the low side. Runs 10% higher than r-12 on the high side. Take note of the ambient temp when charging. Make sure you use a vacuum pump for at least 1hr, longer if moisture got into the system.
From experience, it will make it cool when not driving, but not ice cold. When it feels cool or if using a temp gauge, if you can get it below 50 degrees, leave it alone. I think I had my gauge at 40 low and 190 on the high side at roughly 85ish degree. When you get close to 35 and 170, let the AC pump cycle a couple times before adding anymore. If you do add more, little at a time. Overcharging will make it blow warm.
I did also realize my electric fan was not turning on when I turned on the AC. When it did turn on, it did a better job cooling the air, but not sure if it is suppose to turn on when the AC is cycled on.
https://www.google.com/url?sa=t&rct=j&q ... 5608,d.aWc
134a runs 2psi lower than r-12 equivilant on the low side. Runs 10% higher than r-12 on the high side. Take note of the ambient temp when charging. Make sure you use a vacuum pump for at least 1hr, longer if moisture got into the system.
From experience, it will make it cool when not driving, but not ice cold. When it feels cool or if using a temp gauge, if you can get it below 50 degrees, leave it alone. I think I had my gauge at 40 low and 190 on the high side at roughly 85ish degree. When you get close to 35 and 170, let the AC pump cycle a couple times before adding anymore. If you do add more, little at a time. Overcharging will make it blow warm.
I did also realize my electric fan was not turning on when I turned on the AC. When it did turn on, it did a better job cooling the air, but not sure if it is suppose to turn on when the AC is cycled on.
-
t.mcginley.jr
- Posts: 1547
- Joined: Fri Jun 01, 2012 5:50 am
- Car: 2002 Nissan Altima SE 3.5
1990 Nissan 300ZX NA 2+0
1966 Ford Mustang - Location: New Jersey, USA
Re: A/C system pressures
Thanks for that link bud! I wasn't sure if our cars has specific ranges or if I could use a generic chart like that.
Before I did any work, I checked the system with manifold gauges and there was 0 pressure in the system. Then I went ahead and changed the condenser and receiver drier, and pulled vacuum on it for a good hour (and it held vacuum so I know there aren't any leaks). I added one can of r134 and it was about 30 psi low and 250 psi high, and I probably ~85-90 outside. I drove it for a while with the AC on high and the pressures dropped so I added another half a can and it was back up to those numbers. It gets cool but not cold, I'll have to find a thermometer lol. It's been a week or so since then so I'll have to hook the gauges up to it today and see if I can add more.
Before I did any work, I checked the system with manifold gauges and there was 0 pressure in the system. Then I went ahead and changed the condenser and receiver drier, and pulled vacuum on it for a good hour (and it held vacuum so I know there aren't any leaks). I added one can of r134 and it was about 30 psi low and 250 psi high, and I probably ~85-90 outside. I drove it for a while with the AC on high and the pressures dropped so I added another half a can and it was back up to those numbers. It gets cool but not cold, I'll have to find a thermometer lol. It's been a week or so since then so I'll have to hook the gauges up to it today and see if I can add more.
-
nissanfreak12
- Posts: 1709
- Joined: Sun Jan 23, 2011 4:07 pm
- Car: 92 300zx 2+2 TT
- Location: Denver, CO
Re: A/C system pressures
Is the electric fan running with the AC on? If not, it will only feel cool until you drive it and cool down the condenser. It took just under two cans on mine.
Now the question is, how much oil do you have in the system? Too much will not make the air cold and too little will, well you know, boom.
Now the question is, how much oil do you have in the system? Too much will not make the air cold and too little will, well you know, boom.
-
t.mcginley.jr
- Posts: 1547
- Joined: Fri Jun 01, 2012 5:50 am
- Car: 2002 Nissan Altima SE 3.5
1990 Nissan 300ZX NA 2+0
1966 Ford Mustang - Location: New Jersey, USA
Re: A/C system pressures
The aux. fan isn't running when I switch the AC on. According to this:
Aux Fan Diagnostics
Supposedly if the AC is ON, your speed is below 24 mph, and the coolant temp is below 201 degrees... then the fan WON'T turn on. I verified that the fan works by jumping the relay, so I'm assuming at idle it just doesn't get above 201 degrees (coolant temp sensor is new).
As for oil, I had removed the compressor and drained out as much as I could. Then I added 5 oz. of PAG oil. It called for ~7 oz I believe but I know you can't get it all out.
Aux Fan Diagnostics
Supposedly if the AC is ON, your speed is below 24 mph, and the coolant temp is below 201 degrees... then the fan WON'T turn on. I verified that the fan works by jumping the relay, so I'm assuming at idle it just doesn't get above 201 degrees (coolant temp sensor is new).
As for oil, I had removed the compressor and drained out as much as I could. Then I added 5 oz. of PAG oil. It called for ~7 oz I believe but I know you can't get it all out.