mad scientist:P

what exactly is involved in changing over? my truck is as you know r-12 still. however it does not blow cold. my cousin is an alcoholic A/C man (houses and such) he said to go to NAPA get the adapter for the low side and if its empty try to get a can or two of 134a in it. and if it wont take it then it needs to be pumped down. then my dad tells me that the oil in the compressor has to be changed???

not sure which route to take...cousins is easier but i dont want to ruin somethin. any thoughts?

Spooler

The oil is different. The old R12 oil will not be picked up by the refrig. I have done conversions in 2 ways.

1.) Evacuate, Flush the lines, evap., condensor. Drain and replace the compressor oil. Put adaptors on both the High and low side. Vaccum and check for leaks. Add the 80% of R134a to the system. Calculation: R12 weight required / (1.2)= Amount of R134a to add.
1.80lbs of R12/ (1.2) = 1.5lbs of R134a

2.) Evacuate the system. Vaccum the system down and check for leaks. Add the oil required for compressor, evaporator, compresser, dryer. Install new R134 fittings. Recharge with R134a using above formula. What will happen is the old oil is not picked up by the new refrig. so it stays where it is. The new oil is circulated through the systems as usual. As a rule of thumb I used to use 2oz of oil for each component for a total of 8oz's of oil.

This is from memory 7 years back when I was a tech doing a good amount of conversions. So check me somebody.

dan1stgen

theres also a thread on this in the sticky section.

dan1stgen

to add to what spooler said you should also replace your drier and blow out any lines with accumulators on them they are large round canisters that are pert of the lines. these things will hold moisture and old oil.

mad scientist:P

i see. thanks.

also, forgot to check the sticky sorry.

MJDiesel

Sorry to butt in, but is it really necessary to drain the compressor oil??? The reason that I am asking is because I attempted to remove the compressor, but I found that the little bolts were frozen up pretty good. After breaking a few wrenches and alot of swearing, I decided that it was just not worth it. I have some guages and a vac pump coming my way, so should I just vac the system and then put 8 oz of oil in the pump?

chadwick

i would second replacing the dryer along with a condenser that is made for the use of 134a. The tubes are different shape between r12 and r134, it would work better.MJ i have always changed out the oil just because who ever taught me said that you have to,but i do know that 134 wont pick up the old oil.

mad scientist:P

what kind of price are we talkin to replace dryer and condenser??? i have recharged 134a systems before but never r 12. so im anxious to try this...just dont have a lot of pocket change. can i get one off a 2nd gen truck and it work?

MJDiesel

Both parts were priced at about $60 ($25-30 apiece) through advance auto parts when I checked the other day.

edwinsmith

There is a type of oil that will mix with the old oil and make it compatible with R134A. Get one that says it compatible with both R12 and R134A.

It's important to evacuate all of the R12 for recycling. You can sell it because it's valuable now. Most guys probably just let out the old R12 and then recharge with the new oil and new R134A. Works fine in most cases.

Edwin

mad scientist:P

i see. so im going to try the cheap route first. that being get the 134a adapter for the low side and try to hook up a can that contains oil in it. if that doesnt work then i will try cleaning out the lines, replacing the oil, refrigerant and condensor and dryer.

ok so if i have to replace the dryer and condensor, where are they located? i know there is a black canistor on the pass fenderwell...what is that? condensor?

edwinsmith...where can you get such oil that is compatible w/ both r12 and r134a? autozone? advanced? napa? i would call around but usually when i do that i get some punk kid who knows next to nothing and thinks im stupid. so any input would be awesome! thanks

MJDiesel

The black canister on the fenderwell is the dryer. The condensor is the large cooler behind the grille.

edwinsmith

If there is any R-12 left in the system you should remove it. As long as you immediately put R-134 back in along with the oil you should be fine. Don't overcharge, a slight undercharge is better.

Edwin