So I went out to recharge my AC this morning. After some difficulties, I managed to empty the freon In to the system. I took it for a drive and noticed a noise that sounds like pressure being slowly released, while the compressor is on, and for a couple seconds after it turns off. From the drivers seat, it sounds like it is coming from underneath the dash on passenger side.

It seems self explanatory that there is a leak in the system, and it's letting all that pressure out that I just put in, but I wanted verification. I thought there might be some type of blow off valve, and that it is supposed to be making this noise, but I can't come up with a logical reason for it. Any thoughts?

On a side note, it was hard to tell if it was blowing cold air, as it was only 62 degrees and I probably didn't pit as much freon as the system calls for

 

Not to sound really mean or rude but, If you don't have the proper tools (gauge manifold, suction pump, ect) or the knowledge of with the hell your doing you should just take it to a CERTIFIED A/C TECH...... A/C systems are a dangerous beast and i know of someone that was killed screwing with the system not knowing what he was doing.

As for your question, How do you know what your pressure is or if your loosing it?? those cheap gauges they put of the cans of 134a are just that cheap. most of there time they are not accurate and there downright redneckish... The sound could be a leak in the A/C system but your say it sounds like its from the drivers side so it could also be a small vac leak also. How long is the hissing sound?

 

Your right, it can be dangerous and I don't pretend to be a mechanic. They only reason I do it myself is because the shop quoted me almost $200 bucks to do it for probably $20 worth of freon, the rest labor. I did it successfully for my ram without much trouble.

The hissing sound will start when the compressor kicks on, and continue while it is on. When the compressor shuts off, the sound kind if dwindles and gets quieter, then stops. If the compressor turns on again during this process, the sound will come back again. And i didn't mean it's coming from the drivers side, I meant it sounds like it is coming ffrom the passenger side, while sitting drivers side. Sorry for the confusion.

If it more than just a low charge issue and there is in fact a leak, I will deal with no AC rather than paying a small fortune to have it fixed

 

Ok few questions here....

First, are we dealing with single or dual system.. do you have overhead A/C?

The freon you put in, did it have Dye in it?

With it coming and going when the compressor cycle i would say its a system leak. Most likely it is a bad O-ring or the valve core is leaking.

 

I do have the overhead system, and I'm pretty sure the freon did not have dye. That would be unfortunate but good to know. I will be checking the fittings when I get the chance, in case I can see any of the oil leaking. I know it's not a reliable check but it's a start.

 

Ok you have the dual system then... it needs 30oz to be fully charged.... if the freon does not have dye in it then at this point all you can do follow all the lines and look for "wet" spots. Also since you have rear A/C check the rear expansion valve for leaks. That is located right under the passenger seat on the underside of the truck... In fact that leaking would make perfect sense to the hissing your hearing.. I have replaced mine.. there easy and cheap. the downside is you have to drain the system to replace it..

Just for reference Autozone sells 14oz cans of 134a that has red dye and the oil needed included. When i filled my system i used 2 of them and added a 2oz can of "A/C chiller" to come to the 30 oz required.

 

Ok I will be checking that when I get the chance, thank you for the info I appreciate it.