I have not used my A/C for a long time. It didn't work so well and it made the engine heat up.
Well, now I want to fix it. I gave it a try and it does not turn on. The compressor does not kick in. All electrical is OK, so I checked the pressure. Nothing in the lines, so the low pressure switch is keeping it from turning on.
I still have 3 cans of R12 that I can use, but I don't want to put them in and just have it leak out again.

1) Is there any way for me to check for leaks myself without using up my R12?

2) I always hear about 'evacuating' or vacuuming out the system before refilling it. How do I, or can I, do this myself?

I'll get to the engine cooling problem after I get the A/C up and running again.
Thanks!

 

First of all, pull the low pressure switch plug and jump it to bypass the low pressure. This will tell you if your pump can still turn or not. Second, sell the R12, make some bank on it and then get an R134a conversion kit for $40 and use that to fill your system. You will have to have the system evacuated but if it's already at 0psi then you don't need to do anything. This way if you do have a leak then you're just wasting $6 cans that you can get at any parts store.

If you have any more questions I'll be glad to answer them. Just beware that the old way of changing parts to run R134a is total BS and was only done to milk customers.

 

yep..they try to make more out if it then there is..I've converted several a/c's over to 134a. Pull the needle valves..install the new ones..i usually dump a can of a/c oil in there..then dump the 134a in there. I've never had any problems and i've done several.

 

You will want to try to fix the leak before you charge it. Any and all connections should be scrutanized; traces of oil on a connection mean it's a leaker. If you have o-ring connections, I would suggest you replace all o-rings as they are cheap. You can pressurize the system with nitrogen then monitor the system for pressure loss or use soapy water; don't use air as inevitably it will have some moisture in it (very bad in A/C). You can evacuate the system of air if you can get your hands on a cav pump; it may be possible to rent one. I've used some home made setups over the years that will work just fine. Worst cast is to take it to a local service station and have them purge it for you. Converting to R134 would be a smart move at this time and that R12 is a hot ebay item. If you do the conversion, it would be good to change the orifice tube wheil you're in there. Some might argue that you need a new accumliator/dryer; I only replace them if there is a proven moisture problem or if the system has been open to the atmosphere for a long period. On that note, if you elect to reuse your accumulator/dryer, replace your o-rings and orifice tube in a reasonable amount of time and don't leave the system open to the atmosphere for extended periods of time. If you must walk away from it for awhile, securly plug open lines.

In lieu of pressurizing with nitrogen, you can use the vac pump to see if it's leak free. Pull the vac, then monitor your gauges.

 

The compressor on my '91 F-150 5.0 failed, so I'm not converting it to R-134. I know the orifice tube is located in the inlet of the evaporator, but I can't figure out how to get the liquid line disconected from the evaporator. Any help with this would be much appreciated, this is driving me nuts.

 

the fitting where it connects..is it round looking? they require a plastic round tool looking thing to slip on the line to push into the round looking thing to move the spring lock out of the way then pull the lines apart. you can get the assorted rings at your local part store for about $10. Think that's what i paid for them. They are a good thing to have cuz you can use them to take apart fuel lines also on some vehicles.

 

Thanks,

I was able to fab. a disconnect tool for the snap ring connector using plumbers tape, and things came apart just fine.