AC Refrigerant Spec (1 Viewer)

[dunnyboy]

I believe the factory spec for R12 is 24oz. I have heard that the spec for 134A is in the 20oz range, although a Denso tech stated that the actual Toyota recommendation was 93% of the R12 charge when retrofitting. That would be about 22 oz.

Any voices of experience as to the right charge? My inclination is to go "light" and stick with the 20 oz. charge. If it cools well, then all's well.

 

[vipergrhd]

Not sure if the 60/62 holds the same amount of refrigerant,i would locate your label to find out what is your maximum charge and go from there.Rule of thumb is about 10% less of what the R12 system use to hold,you can also charge it a few ounces at a time and start a baseline around 20 oz.it would be nice if you have an HVAC machine to do this and be able to pull out if you overcharge the system.

 

[fj60dave]

The correct refrigerant amount can be calculated based upon the molecular weight of each refrigerant. The known value in this case the system design for R12. Use an "upper limit" figure of 26oz r12 for this case - start lower and stop when your cooling is correct. You need to know the projected weight of refrigerant needed to help you understand your starting point, and then add until you have optimal cooling. Using this method:

26oz r12 (equals 1.00)
22oz r134a (r12 max oz * .84)
14.3oz r152a (r12 max oz * .55) this is "air duster"
8.6oz es-12a (r12 max oz * .34) hydro-carbon blend

This will help you to hit the mark. You should really purchase a vent thermometer and keep it in the middle vents nearest the evaporator in your cabin. You will then know how your system is performing and will better understand when there are problems. Just my observations over time...

50-59F vent temps feel cool
40-49F vent temps feel cold
30-39F vent temps feel freezing

when providing details for a group diagnosis, it is very helpful to state as much detail as possible, including vent temps. if someone says cool/cold/freezing i think of the above temp ranges.

 

[vipergrhd]

Huh!

Since when 26 oz equals to 1 lb? Typo maybe?Just to add to your comments it is not ideal to mix hybrid refrigerant stick to R134 or R12.most shop will not service your A/C if they determine your system is not pure and it also ruins HVAC recycling machine in the process most shop will use a refrigerant identifier to avoid cross contamination.Just my 2 pennies. BTW it's 16 oz= 1lb

Ideal vent temp on most vehicles w/ R134a should be in the low 40's that is 80-90* ambient temp.
My R12 in my truck will do 36* with the same ambient temp.

 

[fj60dave]

viper - right. 16oz=1-pound.

in the above, where 26oz/r12 is a 100% charge... (1.00)
then the other refrigerants (by weight) are less than 26oz. how much less?
the correct r134a charge is 84% of the r12 charge; the r152a charge is 55% of the r12 charge; etc...calculated by using the molecular weight of the refrigerant.

on a 74F day last week, my R134a charged FJ60 would produce 37F vent temps during a 3-mile trip.

and, correct about charging with non-standards, but that is how to calculate the refrigerant volume - as an example. For people doing the r12 conversion to r134a, multiply the r12 ounces times .84 for the target charge.