100+ PSI on Low Pressure Side of A/C

[motoservdog]

Subject says it all. Car is a 95 3.4L Camaro. It was a hot day today in Riverside, CA and A/C was not cooling enough. So I figured freon needs to be charged. Bought a refill kit with guage and that's what it read. Tried 2 guages, both read the same. So I did not proceed with the refill. Anyone got any ideas on why this is? Will this create any problems with the engine? Any help appreciated. TIA.

[Rob Bell]

Re: 100+ PSI on Low Pressure Side of A/C

Maybe something is blocked in the system, like the orifice valve or something.

[motoservdog]

Re: 100+ PSI on Low Pressure Side of A/C

How do I check the orifice valve?

[Firebirdkid96]

Re: 100+ PSI on Low Pressure Side of A/C

evac the system and take it out

[landj]

Re: 100+ PSI on Low Pressure Side of A/C

was the compressor turning and engaged when you tested it?

[nascar24jd]

Re: 100+ PSI on Low Pressure Side of A/C

Sounds like you checked it when the compressor was not turning. When the compressor kicks in the pressure reading will drop. Maybe it is so low on R-134a that the compressor is not kicking on.

[motoservdog]

Re: 100+ PSI on Low Pressure Side of A/C

No, the compressor was not turning when I checked it. So do I just refill with freon? Instructions on the can said if the pressure is below 25 psi, then freon is low. I'll check again today. Thanks all.

[landj]

Re: 100+ PSI on Low Pressure Side of A/C

Yes and No. If you are getting a high reading on the low side port but the compressor is not turning, then something else is wrong. Do NOT try to put freon in the low port if you have a high pressure reading. I cannot tell you what could happen because the moderator will sensor my post (as they have before, which I'll never figure out, but I digress...) but lets just say that the pressure is beyond the pressure safety factor the can was designed for, you can read the safety warnings on the can for more information.

If the compressor is not turning with a high pressure on the low port side, then you will need to try to troubleshoot the electrical system (pressure sensor, wire to the A/C clutch etc).

I'm looking at your post again... I thought you said it read high, but now it doesn't say that. So I don't know what to say...

[motoservdog]

Re: 100+ PSI on Low Pressure Side of A/C

checked the pressure yesterday and it was normal. ~30 psi is what I got from 2 guages. compressor was engaging on and off, when off, pressure goes to ~40 psi, when on, ~30 psi. is this normal? what could have caused the pressure to go up to 100 psi the other day? now, seems like everything is normal though.

[Rob Bell]

Re: 100+ PSI on Low Pressure Side of A/C

Not sure what would cause it to spike to 100 psi. If it's now normal, and blowing cold (not just cool) air, then I would just keep an eye on it for a while and check the pressure frequently. If it seems OK after a while, then don't worry about it.

[landj]

Re: 100+ PSI on Low Pressure Side of A/C

checked the pressure yesterday and it was normal. ~30 psi is what I got from 2 guages. compressor was engaging on and off, when off, pressure goes to ~40 psi, when on, ~30 psi. is this normal? what could have caused the pressure to go up to 100 psi the other day? now, seems like everything is normal though.

Low side pressure of 30 psi might be slightly on the low side, but it's reasonable. The pressure reading you want is when the compressor is running. When the compressor is off, it will climb, which is why you need the compressor on to take a reading. It will cut off depending on demand (hot it is out, fan speed, yada, yada...).

If it's blowing cold, don't mess with it.

[motoservdog]

Re: 100+ PSI on Low Pressure Side of A/C

roger that. i'll keep checking. it is blowing cold air. thanks for the suggestions.

[KennyD]

Re: 100+ PSI on Low Pressure Side of A/C

Anyone know where the low pressure sensor is located? Can you jump it out to restart the compressure to recharge it?

[Rob Bell]

Re: 100+ PSI on Low Pressure Side of A/C

I'm not sure exactly where the exact location of the sensors are, but they will be along the pipes. The larger pipe is the low pressure side. There may only be a high-side sensor, though.

Forgot to mention, that you do not want to jump the sensor to start the compressor because of low pressure. When you start charging the system, when the pressure builds enough from adding refrigerant, the compressor will start by itself.

[KennyD]

Re: 100+ PSI on Low Pressure Side of A/C

Thanks Rob. I have a couple of cans of 134 stop leak, and was trying to get it to the system. I want to try adding it first, before buying a compressor and doing the swap.