i just purchased a 93 civic ex that the previousowner told me that the a/c wasn't working becuase it was out of freon. my question how much freon do i addand how do i do it. also what is best freon to detect a leaks.

 

To do this properly, you need an A/C pressure gauge so that you can read the freon pressure at the high and low pressure sides of the system. R12 freon is illegal so you first need to find out whether the A/C system has been converted to R134a. If necessary, conversion kits and gauges are available from auto parts stores. Walmart has low prices for R134a. If the system is empty, you may need as much as 23 oz of freon to fill it. The A/C system also requires lubricant oil that must be added if any has been lost due to leakage. As you can see, the project is probably more complicated than you may have initially anticipated.

 

A '93 will probably be R134a from the factory but I think they may have made a few of them R12. Find the service fittings on top of the condenser and unscrew the plastic caps to examine the fittings themselves. If they have threads on the outside with a tapered top it's R12. If they are flat on the top and smooth on the outside with a ring for a quick connector it's R134a.

If ti's a R134a system already you're good to go. Otherwise you should convert, if it is out of refrigerant. These systems are basically the same hardware for either refrigerant so they convert well. But do not use the conversion kit in a box, aka "death kit". A proper conversion involves at least removing the compressor from the car and changing the oil in it. Also the receiver drier must be changed.

Next you can do a quick check to see if there is any pressure at all by very briefly pressing the valve core down like a tire valve. If it has leaked down to zero there is a major leak and putting more in is just going to leak out almost immediately. Also if there's zero pressure, air has probably found its way in thru the leak and the air needs to be pumped out before recharging. Find the leak first.

If there is pressure in the system it may actually be properly charged, but there is another problem. So don't just start charging.

It's quite practical to do A/C work yourself but you do need to invest in some tools. You must have a professional type gauge manifold with two gauges on it. This costs about $80 and up at parts stores. Don't get the really cheap one that only has a can tapper permanently attached to the yellow hose. You can't use that one to evacuate air, which is essential for good results and long life. As far as evacuating air, you'll need an electric vacuum pump which costs about $200 but you can also rent or borrow those. The cheap venturi type vacuum pump that is driven by compressed air does not develop sufficient vacuum.

 

You can track a leak using UV light-reacting dye, they sell those kits at most autoparts and just put the dye in the system, and start looking at the hoses, connections, compressor, and condenser. Also if you see the water coming from the evaporator has the dye in it, most probably the evaporator is leaking. make sure you wear the yellow glasses most kits bring because they will protect your eyes from the UV light and it will make it easier to see the dye.

 

For UV dye to work the system must be fully charged and running. So you should wait for warm weather to do that. While the car is parked, the dye sits still and only gas will escape from leaks. UV dye is certainly a good method in many cases and it is good to run UV dye all the time in your system so you can find future leaks more readily.

If you have a pressure of zero start with a physical inspection. Look for broken, cracked or corroded parts. Leaks will often have oil around them. Then try adding a small amount of R134a and go over everything with a "sniffer" leak detector.

 

I forgot to add that information, Thanks!

 

thanks fella's allgood information