Do I have to vacuum out the old AC refridgerent if I am replacing with new parts?

[stinkydogfilms]

Hello again,

I am trying to start replacing my AC compressor, drier, evaporator and condenser in the 1991 GM. My system has not had AC for a couple of years. The compressor does not turn on and I checked the fuse at the fuse box. It is the original system (1991), so I want to replace as much as I can.
I pressed in the release valves on both the lo and hi sides and nothing comes out.

Can I safely remove the hoses at the compressor and the fittings at the drier and condenser without tearing off my hand due to a pressurize system?

Is there any way to check the pressure without the compressor running?

What if the hoses ""accidently rip"" and I take the pressure off that way.


If I have to vacuum it all out, how do I do that with a compressor that don't work?

I plan on replacing the hoses with new. After the new parts are in, I plan on taking it to a professional to charge it up.

My THANKS AGAIN,
Mike

[kodiak]

Oh boy! Not knowing anything about AC and working on it is not a good idea. Some systems have a low psi switch that cuts out the compressor.

1.The compressor is a pump that moves the refrigerant from one side to the other.

2. If you have no pressure at the service ports, there is no pressure in the system.

3. Moisture is a refrigeration systems enemy.

4. A two stage vacuum pump is used to evacuate the system not the compressor.

5. If your system has been open to the atmosphere you HAVE moisture in the system, including the refrigerant oil.

6. Dry nitrogen should be used to blow thru the system, check for leaks after repair and suck up small amounts of moisturize.

7. Air and refrigerant do not mix. Air in a system effectively reduces the condenser size and causes acid to be formed as the moisture in the air mixes with the oil.

I am a Refrigeration tech by trade.

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[crazyman]

What he said.

[kodiak]

BTW, refrigerant has a pressure/temperature relationship. A certain pressure equals a certain temperature. R134a at 70*F equals 71.2 psig. It won't "blow" your hand off BUT you can get severe freeze burns.

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[79lincolnlover]

Safety 1st!

[chitownvic]

X2 on what Kodak said! I have my done by friend who knows what he's doing. He's an HVAC guy by trade and bought a nice little compressor and manifold gauges off amazon with an adaptor kit.. Good hook up R134 and nitrogen so a good friend to have.. If you're hell bent on DIY just do your homework and be safe


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[gadget73]

well, if you have pushed in the pressure ports and nothing came out, there is no pressure in the system. At that point its just plumbing. But yeah, the system needs to be evacuated and all that otherwise its not going to work right. Air and moisture in the system will give you bad results. If you want to fix it and save yourself some money, my advice would be to assemble the system and then take it to a shop for the evacuation and charge.