Air Conditioning Question

[cblackb]

Hey All, I noticed that my A/C wasn't blowing very cold so I went and got a new can of R134 to put in. Well, with the A/C on max the compressor was kicking in and out constantly and then after the R134 it now at least stays engaged all the time..which is good. However, I checked the pressure on the low-side and it was still low, so I added another can. Now it's just into the "full" range, but that's it. How many cans of this stuff should I put in? Also, I noticed that when I shut off my truck and the A/C was on, I hear a slight hissing noise coming from the area where the A/C hoses go into the firewall, is this normal or do you suppose this might be where my leak is? This hissing noise stops after about 10 seconds or so, like it's bleeding off pressure and then stops. To my knowledge the A/C system on this truck has never been serviced before now. Thanks!

[pipelayerjdh]

Did you try the 134 w/ stop leak? I have had to use more than one can before. Just don't over fill.

[cblackb]

No, I've not tried the stop leak yet, just regular 134. So I'm taking it that the 10 seconds of hissing of after I shut the system off is NOT normal then? Does yours hiss at all when you shut the truck off after having the A/C on for awhile?

[2006PSDSD]

The hissing that your talking about is probably from the two lines (suction and discharge) equalizing their pressure through the metering device. Look around your entire a/c system, and if there is a leak to worry about you will likely find an oil stain or slick around the leak. If there is a leak, you will have to take it to a reputable shop and have them repair it because afterwards they will need to pull a vacuum on the system to remove any non-condensables (moisture, air). Hope that helps

[tonyf250]

If you read on the tag somewhere around the hood latch it will tell you what the capacity is for the system. You will be able to tell how low you were and if you have overfilled it. The hissing I am sure is the equalization of pressure. As stated before the oil residue will be a identifier that you have a leak and where it is.

[cblackb]

Oh good, I'm glad to hear that the hissing noise most likely is normal, thanks for the info. I'll check that tag to be sure but the A/C seems to be working a heck of a lot better now, maybe it truely was just low. Usually with my luck nothing is ever "just low", it's usually broke and is very expensive.

[djordan1184]

On the 2006s there was a tsb that came out that there a half a pound to lowfrom the factory.when I took mine to scott he added more.I'm not sure if it is for the 2000 or not

[Blue01F250]

Most systems only carry 1-3 lbs of refridgerant... the most cars are about 1.5 - 2 lbs. So if you are completely empty, you'll probalby only need 3 cans MAX. And all my vehicles make that hissing sound - you're good to go there...

[KAW3604x4]

I never shut my truck down before turning the A/C off. I let it idle a few seconds after shutting the A/C off. So, I have never heard the hissing sound you are talking about.