AC Low Pressure Port?

[tbauer03]

I replaced my compressor, accumulator and orifice tube the other day. Today I went to charge the system using a retro fit kit and the only low pressure fitting in the kit was 7/16" which only fit on the accumulator so i just assumed that was the low side and the tubing with the 3/8" fitting was the high pressure side.
I put a vacuum on it for about 15 minutes and it held the vacuum for 24 hours so I went ahead and stuck a can of R134 freon and began to fill. It filled up real quick and only took about half of 18oz before the can and system equalized around 40lbs. while the gauge i had on the high pressure only read about 5psi. I believe I have the ports backwards but can someone confirm before i attempt to fill through what may be the high side as I am confused to why they only gave me a low pressure fitting in 7/16". and if I doing something wrong let me know it wouldn't be the first time.
Here is a few pics of the operation.
Thanks for your help.

 

[leroy]

Re: AC Low Pressure Port?

You have it right.

Jim

 

[tbauer03]

Re: AC Low Pressure Port?

Thanks Jim.
I realized the compressor isn't kicking on. Which is why i built pressure quick in the low port and nothing on the high side. I believe I have a vac leak behind the ac controls because It is only blowing air out the bottom vent. The engine bay vac lines all appear ok and I can hear a variable hissing coming behind the switch panel depend on where i have the switch.

 

[TNPhoon]

Re: AC Low Pressure Port?

I believe I have a vac leak behind the ac controls because It is only blowing air out the bottom vent. The engine bay vac lines all appear ok and I can hear a variable hissing coming behind the switch panel depend on where i have the switch.

I will be interested to see where you find your vac leak at. Mine's doing the same thing only out of the top defog vents. Everything under the hood appears okay and right behind the controls when I took the gauge cluster out was okay too from what I could tell.

 

[tbauer03]

Re: AC Low Pressure Port?

It was leaking at the wheel where the vacuum lines come together behind the controller.
This thread depicts exactly what was happening.
I now have air blowing out of my vents and and I can toggle between floor dash windshield just fine however my compressor is still not coming on. The temp thing works as well. When i put it on hot i get hot when I put on on cold I get cooler air, just not fridged compressed air. The wiring pigtail in the engine bay is plugged into the compressor.

Any ideas?

Thanks.

 

[gkrcr882]

Re: AC Low Pressure Port?

Vehicle running you should have between 20 and 30 psi on the low side and around 200 high side. Are you charging as a liquid or a vapor? If you're careful you can charge as a liquid on the low side with the system running, however go slow so no liquid enters the compressor.

 

[Brassmonkey]

Re: AC Low Pressure Port?

If your compressor is not coming on, you might have a bad low pressure switch. This is the switch that screws onto the back side of the accumulator. Use a paper clip to jump the circuit to see if the compressor comes on. I hope you added some oil to the system.

 

[SY2932]

Re: AC Low Pressure Port?

Heh, I was going to post a link to that thread when I got back home, glad to see some on here still use the search . With regards to the compressor not coming on, you will need to short the pressure switch with a paper clip to fool it. Because it won't cycle if there isn't any pressure in the system. But you have to get *some* in there to make it work. Automotive catch 22. If you are using a bulk tank, i would highly recommend using a scale to monitor how much refrigerant you are putting in. Because it will need a specified amount.

 

[gkrcr882]

Re: AC Low Pressure Port?

Automotive catch 22. If you are using a bulk tank, i would highly recommend using a scale to monitor how much refrigerant you are putting in. Because it will need a specified amount.

The measured/weighed charge is the best (and only except for automatic machines IMO) way to charge an A/C system. The pressure gauge and can thing is a best guess in most cases.

 

[tbauer03]

Re: AC Low Pressure Port?

Heh, I was going to post a link to that thread when I got back home, glad to see some on here still use the search . With regards to the compressor not coming on, you will need to short the pressure switch with a paper clip to fool it. Because it won't cycle if there isn't any pressure in the system. But you have to get *some* in there to make it work. Automotive catch 22. If you are using a bulk tank, i would highly recommend using a scale to monitor how much refrigerant you are putting in. Because it will need a specified amount.

Jumping that circuit worked. She is throwing ice cubes out of the vents now :tup:
Wish I would have done this work many years ago.