Time to Replace A/C refrigerent
 

Has anyone used the R12 replacement freeze 12 in their A/C systems. I am debating whether to use it instead of going to R-134. Any suggestions?

I put the product from Red Tek in my system several weeks ago after replacing all my hoses and the dryer. Seems to work fine, can't say its any cooler. Takes only about 1/3 the amount and the price is right. I also "cleaned" my two condensers. My system seems to be leak free and the AC shops in my area aren't that great so I invested in the vacuum pump and gages to do it myself. So far, no complaints other than the system still only works marginally well. May need to fine tune the amount in the system or over the winter, remove the evaporator and assure its clean. I do like that it really just propane and butane mixed and not too bad to vent to atmosphere as necessary.

I have used freeze 12 in my other older cars. I do not know what its thermal capabilities are related to R12, but it seems to work well

How do you determine a proper charge when you've made other changes, i.e additional condensers? I just got freeze 12 and was using Duracool. I calculated the amount of duracool based on a ratio from the manufacturer but now have added a third condenser. Do we just use our gauges to get the correct amount? I was getting about 25 on the low side and 225 on the high, which seems to be about right...correct?

IMHO you should keep an eye on vent temps and stop adding when it stops getting cooler.

If you're going to use some rinky-dink shadetree mechanic method then there are much better ones than the one you suggest. Besides which the time constant of the system is too long for that cooling "delta" procedure.

The below assumes the capillary sensor/switch temperature comtrol system is fully and correctly functional. The sensor bulb/tube should be close enough to the evaporator vanes, inserted/ buried within, to detect and prevent freeze up of any condensate.

With car parked under cover, "shadetree", close the cabin up for minmum ourflow, turn the A/C control all the way to max cooling but with the blower speed set to minimum. Assuming the system is somewhat functional the cabin should cool to something below your comfort range, ~65F, within 10-15 minutes and have dash vent outflow temperatures below 45F.

To prevent freeze up of the evaporator the compressor should begin cycling off and on.

Only add refrigerant an ounce or so, at a time, 5-10 minutes between fillings, until the compressor cycles on and off every 2-3 minutes.

fan speed on HI, charge until it STOPS cycling at around 1500-2k rpm, if it cycles at all. then add a little more.