Automotive Air Conditioning Information Forum (Archives)

dur65geo on Sat January 11, 2014 9:05 PM

Year: 1999
Make: VW
Model: Jetta
Engine Size: 2.0
Refrigerant Type: Freon

My '99 Jetta with 90k miles had ice cold a/c until last week. Now it blow cool for a while, then cold again, then next use cool again. I'm going to add Freon to see if that's what's needed. My question is: does Freon dissolve or deplete over time, or do I absolutely have a leak somewhere?

thanks.

Dougflas on Sun January 12, 2014 5:30 AM

Quote
Originally posted by: dur65geo
My '99 Jetta with 90k miles had ice cold a/c until last week. Now it blow cool for a while, then cold again, then next use cool again. I'm going to add Freon to see if that's what's needed. My question is: does Freon dissolve or deplete over time, or do I absolutely have a leak somewhere?



thanks.


Systems do not consume freon. You may have a leak or a stuck control valve in the compressor. First step I would do is recover the freon and charge the correct amount back into the system. Then We would know if it was a freon problem or not.

dur65geo on Sun January 12, 2014 9:27 AM

my thought too, perfect thanks.

Cussboy on Mon January 13, 2014 1:55 PM

Quote
Originally posted by: dur65geo
My question is: does Freon dissolve or deplete over time, or do I absolutely have a leak somewhere?

No Freon (R-12) or R134a does not deplete or dissolve over time. If you are low, then the only real way to tell how low would be for a shop to remove and measure what ihas remained. And then the leak must be fixed, then the correct amount added aver evacuation.


Quote
Originally posted by: dur65geo
I'm going to add Freon to see if that's what's needed.

That's not the right way to diagnose or "fix", see above. If you've lost refrigerant (R134a in your case with your 1999), then you have a leak. Trying to get lucky and have it work for a little while 9because leaks will NOT get better) is the Gomer type of repair that got the world into the whole R-12 stoppage fiasco.

mk378 on Thu January 16, 2014 8:44 PM

Since it gets cold once, you have enough refrigerant. There aren't gremlins under the hood taking it out and putting it back. In other words, intermittent cooling is not caused by lack of refrigerant. So don't add any.

Most VWs have a SD7V16 compressor, which is a variable displacement unit. A common problem with that compressor is the variable displacement will get stuck at a low displacement when it should be high, then you have little or no cooling.

NickD on Mon January 20, 2014 2:18 PM

Freon is a DuPont trademark for R-12, your vehicle uses R-134a so if like using tradenames have to call it Suva.

Variable displacement compressors like the old POA valves are very difficult to charge via pressures. Lots of other variables besides ambient temperature and humidity. Only recommended way is to use a charging station, it extracts the refrigerant and measures it, either add or subtract to that level so it meets the vehicle's recommended capacity.

Poor cooling is always blamed on low free-on, can be electrical problems, drive problems, and even filthy evaporators or condensers. You risk overcharging the system where it can blow its cork.

Little difficult to think about AC since it was 12 degrees below zero this morning here.