A/C leak help

[Diesel]

When I put a vacuum on my system I can hear it hissing from around the front of the truck. I am having trouble figuring out where the leak is. Is there a particular part that typically leaks on these trucks? I want to get the system leak-free so I can get a local a/c place to fill it with some of that r12 substitute.

[slow_90firebird]

Probably the condenser, they can get hit by a rock and leak like antifreeze from the radiator.

If the system has been without freon pressure for any amount of time, you should probably change the reciever/drier because the desicant bag in there will soak moisture from the air in no time.

Also make sure to add oil, mineral oil is best but Ester oil will work with r12 and r134a.

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If you just want to check that everything is in working order to blow cold air, you can (illegally) charge your A/C with propane. I used it in my firebird and i even mixed it in with the little bit of R12 that was still in there, and it blows way colder than my dodge. And it uses about 1/3 the amount of propane as it would R12 to acchieve the same effect.

But like I said, its illegal, and of course there is always the fire hazzard if you got a leak in your evaproator.

But the main reason it is frowned upon is because it would contaminate some mechanics freon machine and whole 30 lb can. So if you do try it make sure you vent it all out and then suck a good vacuum on the system before bringing it to an A/C shop...

[ellis93]

No using propane is not a fire hazard, its a bomb hazard.

Its my experience that the best way to get a long lasting a/c system is to flush the whole thing and start new with the oil. As was said before a new dryer is a must.

The reason for the flushing of the system to rid it of the old oil is because mineral oil and ester oil mixed will make a black residue inside the system. Which in turn will lead to compresser failure. It will not happen quick and may take it more than a year or so to show up.

I converted my truck to 134A about 5yrs ago and used pag oil ,its what I had from the chevy ac work I had done. Pag oil is synthetic so I know for shure it will not mix with the mineral oil or ester.

[bmoeller]

As was said before a new dryer is a must.

Yep. Anytime the system is opened, it is best to replace it.

Could even have bad o-rings too. Had the expansion valve take a dump on one of the KW trucks a few yrs ago.

[Diesel]

Ok I have a new receiver/dryer and o-ring kit coming. Other than a condenser could anything else leak out between the fan and motor area? Could the compressor have such a huge leak?

[Diesel]

OK will be installing o-ring kit sometime tomorrow. Anything I should watch out for on the installation?

[slow_90firebird]

I think your biggest issue first is the leak up front, if it is the condenser you will need to have it repaired or replaced.

ive never taken apart the A/C on my truck, so im not sure where the o-rings are at, but I do know with any of them, if you can locate a little refrigerant oil (mineral) it would usually help to lube them before you install them. Or just use a dab of motor oil on your finger if thats all you have.