To get high pressures down relay condenser fan to engage with compressor . All R134a systems will run at higher psi vs a R12 system 20-30psi higher is common . Refrigerant charge to 95+% so system will perform .If the high side psi is high you need more condenser or fan or both . Remember compressor oil needs a full system to circulate properly .
I've done them that way, but it's not the best way. One of the advantages of an electric fan is it can be off when it's not needed. At freeway speeds with ambient air rushing through the condenser, for example.
99% of automotive condensers are around 50% size they need to be [fixed displacement compressor ] Common pressures high side are 200-250 psi R12 R134a . Industrial R12 systems run at 130psi PT chart converts this to 150 psi for R134a . How do you achieve this is by running 1 large condenser or 2 smaller units . This works on all trucks/buses and industrial equipment some auto . WHY do you need this is to get the temperature of refrigerant down this is very important for evaporator performance in very hot weather . Yes I have tested auto a/con systems while driving . Pressures vary very little . As I said in most cases condensers need to be alot larger . Later model 2005 on variable displacement compressor have ECU controlled fans . High side psi in late models can run as little as 60-80psi I have done hundreds of dual condenser upgrades and compressor wired fans . All were very successful ie evaporator could cope alot better with very hot weather.
I have done about 10 R12 to R134 conversions on Chrysler products with few problems. I have always used the old compressor and charged to the R12 specs. I completely flush the lines, condenser, evap, and compressor with paint thinner to try & remove as much of the mineral base oil as possible. I replace the accumulator and expansion valve. Then I flush with denatured alcohol to remove residual paint thinner. Never a problem, the systems functioned for years after. Recently did a conversion on my class B Dodge camper and had to replace the compressor. After about 6,000 miles the comp started making noise so I'm having to change it out for another. When draining the old comp I noticed the oil was black. I suspect a chemical reaction between residual R-12 lube & residual PAG oil that came with the new comp ( drained as much of the PAG oil as I could). Seems that all replacement compressors come with PAG oil which is not compatible with anything left over from the R12. Question, does anyone make a compressor that has POE oil in it? Seems stupid to make a compressor that is knowingly going into a vehicle that originally had R12 and then pre-filling it with PAG oil. Some suggestions would be appreciated.
Some compressors have Teflon in them, and when they wear creates a condition called 'black death'. Look for material in the screen in the system, which is the orifice tube with cycling systems, or the dryer in expansion valve systems.
@@ricksshop Done cut the receiver dryer open & no material of any kind, metal or otherwise. When aluminum deteriorates the powder that comes off is black. Currently I'm doing a thorough cleaning of the condenser using an aluminum cleaner, water with baking soda & clear water. The bulk of the black stuff seemed to be in that unit. Evap didn't have much. Kept getting more & more while flushing with paint thinner, alcohol, & system flush. After the water flush I'm going to flush with denatured alcohol & system flush & hope for the best. Alcohol will displace any residual water in the condenser and the current heat will evaporate the alcohol. Vacuum will handle the rest. I was just wondering if you have had problems with replacement compressors on old R12 vehicles. This is a first for me, never had a problem using the old compressor. Thanks for the reply.
not the oil new parts just dont last iv had many bad out of box parts for 134a that was original 134a long as its flushed the tiny bit f left over oil want cause damage the Teflon turns to black oil you want see it
The compressor is drained by removing it and spinning the shaft with the ports angled down. The accumulator previously used in an R12 system will have to be replaced, as the oil can't be drained.
I have a 1988 S10. The r12 compressor locked up. I replaced with a bypass pulley for many years. I now have ordered a new compressor rated for 134a. I have flushed the entire system and will replace the accumulator, orifice tube and all O-rings. The new compressor comes pre-loaded with oil. Instructions are to sit the compressor up on its “front seal” for 15-20 mins before installing. I assume since it is pre-loaded with oil I don’t need to add any more? Any help appreciated.
Did you see any sign of metal or other contaminants in the system from the dead compressor? If yes, it's a good idea to replace the condenser as well. Compressor oil charges are usually over what the system needs. It's best to drain the compressor and measure out the correct charge and re install. I put 2-3 ounces of the measured amount in the compressor and the rest in the accumulator.
@@ricksshop I didn't see any shavings or anything when I flushed. So... new Compressor and Accmulator, Flushed all lines, condenser and evaporator. given the compressor has it's own oil - Do I need to add any more? just pour in vaccum line ahead of charging with 134a? Thanks again!
its probably a good idea, but if it can be saved, why not. its not really woth spending lots of money on an old car. might as well buy a newer one if your spending 1/2 the price jus to fix the a/c
@@Pokingclams I don't know what your numbers are, but I spent $500 on fixing the ac on my 1991 nissan maxima. Needed new compressor, expansion valve and o rings
@@Brandon-uy1uv new car prices divided by 1/2. From your 1st post. On another note. It's nice that you are ok. I saw the post age and started thinking we never know if who we are replying to are still around. Never thought about it before
I tried to retrofit to ford Gran Torino, from r12 to r134A, the compressor and the filter dehydrator were changed, the system was cleaned, it was made a deep vacuum and when I put the r134A the compressor started to make a little noise, I continued filling until in the low pressure gauge I had a reading of 25 psi, I checked the temperature but it didn't cool, I continued to apply more r134A until I reached 40 psi, but it continued the same, I accelerated the car to see if it improved but a loud noise was heard and the engine was turned off, I turned it back on and I realized that the compressor had been tied, what do you think happened?, what did I do wrong? The compressor was recently repaired in an authorized center, it had its oil and they also changed the dehydrator filter, what are the reasons why it could be tied, will I need something to replace? Best regards
I have coroola 1992 model ae101 . Ac was r12 . I just change the compressor with 134a compressor. condenser bottle change . Rest same setup but i clean line . Car doesn’t cool that muah in summer ar day time when specially ideal speed . Can u tell dis i did right . Or what else parts i need to change as well?
I have a 65 chevelle with factory AC. I’m converting to 134a. Adding new lines, drier, condenser. Using ester oil. Did stock AC systems back in the day ever use high pressure shut off switches like You discussed? How do I know if I already have one built in? Thanks again
Most rear drive R12 cars only had a low pressure switch. With R134 it's a good idea to at least monitor the high pressure on a hot day. If pressures ever climb above 450 psi a condenser fan is a good idea (and will make the system work better to boot).
There is a depressor in the switch. I usually loosen the Schrader a turn or two just in case it doesn't make contact. That way it will function and still be removable without losing a significant amount of refrigerant.
Converting may be possible. All of the old mineral oil must be removed, this requires replacing the accumulator/dryer and flushing the system. Most vehicles were on R134 by 1994. Are you sure it's R12?
Having trouble finding the fan switch yo mention with two sets of contacts. Checked all years 93-98 ford tbird at Rock auto but no luck. any part number or other vehicle that may have this switch?
What about getting rid of the old oil? basically you need to replace every damn component on the vehicle and be sure the compressor you buy doesn't come preloaded with the wrong oil. Shops that do the retrofit don't put that switch in so it must work without it and you spent too much time on it. From all the videos I've watched it doesn't seem that there is ANY good way to do this its all up in the air if its going to work or not. It almost seems pointless.
It's not necessary to get every drop of oil out of the system, just most of it. 90% of the oil is in the accumulator and compressor, the rest of the system can be flushed with solvent. If there's any doubt about the condenser, replace it.
