This truck is the old r12 system, drained the system complety of old freon.
tryed to refill the system with 134a and it will only let me put about 12 oz or 1 small can of freon, before the pressure is to high and wont take any more,this refill was done while the truck is running and a/c is on.I have performed this conversion several times before on other r12 systems with no problems, can you tell me if there is a part of the system that controls the pressure? and why its not alowing me to fill the system to full and blowing cold air?pump does engage when it take the first can.
Here is my opinion:
If you just change the type of refrigerant, there are many other things to consider.
The most important, i guess, is the fact that you have the change oil and accumulator receiver, along with a complete system cleaning in order to remove ALL of the type of oiul used for R12.
This is because, if you dont do this, the compressor will fail, due to the oil for R12 and oil type for a R134a system.
Try it this way, it should work good.
Also check your suction line valve for a clog or your gauge manifold blue line rubber gasket, and do not apply too much force when you hook the hose to the valve, as this may reduce the quantity of refrigerant going in the system.
Hope this help....
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I think you can still find the old R12 at a premium price. It would be worth it if your air con system holds well with no significant leaks. Genuine 12 Refrigerant LARGE SIZE 2 14 oz Cans
The old refrigerant and oil are not compatible with the new stuff. The expansion valve is questionable, may or may not work properly. The oil in the compressor, in the evaporator, in the condensor, and in the accumulator/filter/dryer need be removed thuroughly. New service port adapters are installed. Then the new R134 can be introduced. You may find a conversion kit with instructions.
I recall a bulletin calling for replacing the oil and reusing the refrigerant, repeatedly, 2-3X, the final oil replacement gets the new refrigerant.
When ever the system is exposed to the atmosphere, it should be evacuated before refilling. So much to think about and consider.
As far as I know you only have to change the compressor and
dryer-filter to comply with 134a. Other components from old Freon 12 are safe
to use for 134a. There's an Urban (mechanics) legend that you can use a 134a to
an r12 system, but you can't use an r12 to a newer 134a system. But be on the
safe side, change the compressor and dryer to use 134a or ask an expert on
What I would try first is recharge the a/s system, your car came with R12 freon, that type of freon is impossible to get these days, so you will need a retro fit kit to convert it to 134A freon, the kit will have two 134a fittings that screw on to your R12 port, so that the 134a recharge hose will go on, the low side will be the one your add freon through, it will be the thinker hose of the two, the thin one is the high side stay away from that one, you will also need one can of freon (134a), if it works, it might work for a while till the freon leaks out again, then you will have to take it it for repair, but this way you know it's just a leak and every thing else works.Good luck, let me know if I can be of more help.
Must be Air-Condition System Lines/ Hoses leaking R12 Freon (gas). MAYBE THE PULLY HUB BEARINGS FAILED OR DUE TO VERY LOW R12 FREON (GAS ) will not work. Because there is a switch in the receiver/dryer prevent AC from working when low R12 Freon present, to protect the system & compressor damages. You must fix the leaks, before recharging it. They must **** the old (residue) gases from the system & lines / hoses...... & stay in the vacuum pump 30 minutes to proof no more leaks. Recharge some oil for the old type R12 Freon gas. Before recharge it to 62-67 psi R12 Freon See the web site like www.youtube.com/video site to see How they service & repair air-condition system? Put the question to their search window. This is the question u should. How they service & repair air-condition system? Regards; MAR
If it leaks 134 it will leak R-12 .I have changed hundreds of systems over to 134 without any complaints. Don't let the 94% eff rating of 134a scare you because that does not mean that your ac system will lose 6% cooling ability .A large class 8 truck or maybe a high roof van black on black and poor insulation might tax the system in the 90% range on 100 degree days but most systems never get close . 134a high side pressure will be about 18% higher so most systems you need to change the high side cutout.The R-12 electric fan switch will be ok just make sure it is engageing the fan when the pressure comes up.You must check the condensor in front of radiator to make sure air flows easily thru it.On systems where the hoses screw on each side of the dryer I replace the dryer .Drain oil from compressor and replace with 134a oil .Replace that bad valve core (with ac valve core not a tire valve) Now very very important vaccum the system and if no loss of vaccum in 20 min charge with manufactors recomended amount of oil and freon.If a system is low on freon (cycling in & out on low pressure switch) you can add a pound of charge with those small cans of same type freon no problem but when there is a leak and the charge has been lost or changing freon types you must pull a vaccum to properlly charge the system. If you just charge R-12 or 134a your system will have traped non -condensables and a large drop in cooling ability. Hope this helps. Harold