AC Test?

[dalinxz]

Hey So I did a search but couldnt find anything, so basically how do we test an ac that has no coolant. My uncle said there's a way to bypass it by shorting some connecters. Because its a failsafe not to damage the compressor due to no coolant. So he said you have to short it to test it and it wont damage it if your just checking. I just dont want to buy and waste coolant. So basically how do we test it?

[Swap_File]

If you just want to test to see if the compressor will run, apply 12 volts to the wire that goes to the AC clutch. It should engauge the compressor.

Here is an post I made on another forum recently about fixing and filling AC systems cheaply:

I have done some AC work on our cars and tractors. The cheapest way I have found to fill/fix/convert old systems is to...

1. Replace all the broken parts on AC system, and always replace the dryer. Get the old oil out if you are switching refrigerants. Probably a good idea to clean out the old oil even if you are not.

2. Pull a vacuum in the system. The device linked to below works fine, and its cheap, but its slow. Make sure your air compressor is working good so that it can feed it enough air.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92475

It may also be useful to get this other vacuum too, because it has another size of acme to pipe thread adapter. I have found it is cheaper to buy this whole unit on HB, rather than buy the little thread adapter at Napa (they want $40).
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=3952

Also I use this set of gauges for filling and testing:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92649

And... if you are buying from HB, heres the coupon page
http://www.billt.com/harborfreight.htm
(I always like the "Free Leather Gloves + $5.00 Off" coupon)

3. I generally use r134a because its cheap, and available locally. Make sure your compressor can handle r134a if it doesn't already. There are other alternatives like envirosafe, but I have not used them much. Remember to put new oil in for your refrigerant, and maybe some leak finder. Some cans of r134a come with this stuff in it already.

I have also found it is generally easiest (and cheapest) to convert everything to r134a connectors, even if you put envirosafe or similar in. Just make sure that you know what is inside your AC system.

[dalinxz]

thanks do you apply 12V with the car on or off and also does it matter where the positive and negative go? Sorry I am a complete idiot when it comes to AC

[Mac]

If you want to see if you are low on freon you can just pull off the plug on the low pressure switch. It is on the line by the receiver dryer, and short out the 2 sockets. Then run the engine and turn on the A/C. If the fans come on and the compressor engages you are probally low on freon. Don't run it for a long time, just a quick check then turn off the A/C. You should find the leak and fix it.