Warlockk

Pick up a thermometer. Any good tool store has one. Harbor freights has manual ones for a buck or two. Search google for your specs and stick the thermometer in the air vent closest to the blower and let it get cold. All cars have different official ways to test but you should get down in the 30's in a reasonable amount of time. Even if you don't know the exact procedure you can get a pretty good idea what's going on. I thought my truck was working pretty good until I tested it in class and found it barely made below 60*.

Lightning LA

I'll definitely check the Temp 1st to see what it's putting out,and then I'll go from there if I need to...

Bob Gervais

A few things to check, before you add anything:

-Make sure the condenser isn't dirty. It's in front of the radiator, so it's pretty easy to check and clean. Take off the grille, and see if there's any crap packed in the fins. While you're there, it won't hurt to rinse it with a garden hose.

-Check the pressure, at least on the low side, with the AC running. Pressure is directly related to ambient temperature. The higher the ambient temp, the higher the pressure will be on the low side. Whatever gauge you get should have a chart with it to tell you what the low side pressure should be.

-As mentioned, check the vent temps with a thermometer. Vent temps are also directly related to ambient temp. Higher ambient temps will result in higher vent temps. You may get lower vent temps while driving vs. idling. Your vent temps will NOT drop into the lower 30s. Expect to see 38-40 degrees, depending on ambient temp.


If all of this stuff checks out OK, then your system is fine. If any of these things don't check out OK, you'll have to dig a little deeper into your issue.

With low miles on an older vehicle, it's possible for refrigerant to leak past old lines, and o-rings. The fact that the AC still cycles and works means that even if it is low, it's not low by a lot, and it's perfectly acceptable to add some refrigerant from a can/hose kit.

If the system is really low on pressure, you'll need to find the leak, and repair it. If the system is opened to repair a leak, you'll want to install a new accumulator and orifice tube before pulling a vacuum and charging. With the cost of replacement parts (hoses, o-rings, accumulator, and orifice tube) being reasonably low, it's probably not a bad idea to replace everything if you find a leak.

If you do end up having to pull vacuum on the system, let the pump run for as long as you can. 2 hours isn't necessary, but it can't hurt. Once you turn the pump off, leave it connected, and watch your gauges for a couple hours to make sure it holds vacuum, and you have no more leaks.

Warlockk

Once again the problem with "topping off" with a can set is that you are not removing any trapped air or water. Even a good sealed system will develop contamination after years of use like these old systems. The hoses literally leach vapors over time. New vehicles have better hoses of better material and even those will eventually leak. Not to mention the old style o rings our trucks use are degraded by the chemicals, temps, etc. Its not a terrible thing to just top off but you will get much better results from using the proper procedure. Its a cost vs benefit situation.

Aside from that all very good advise. Definitely inspect and clean the system. Oh and to clarify repair the leak, DO NOT use leak stop. It clogs everything much like radiator leak stop does. It also damages a/c machines so a shop will not service a system with stop leak in it. If they have the equipment they will charge a nice fee to remove and dispose of the refrigerant. Then flush the system then charge it. Then you have to hope the flush didn't cause any new leaks that need fixing. Find the leak and replace the detective part, hose or o ring.

keperman

anyone know what the low side and high side pressure should be or a range?


I have a '93 F 150 302/auto, orig R12 system.


Thank you