just had a shop change my r12 to the new 134,,,now at idle it keeps shortcycling the compressor and starts blowing warm air..once on the road it geta a little cooler,,but not even close to old r12...they didnt change anything other than the refrigerent?....they rechecked pressures and said both sides are good???...any ideas?

 

check to see if they're a bunch of leaf and other assorted garbage build up between the condensor and the radiator, a plugged up condensor might cause those problems.

 

Hello and welcome to the Aerostar forum on FTE!

Two things come mind that might be causing your problem. At idle speed or slow, stop and go type traffic, any r134a conversion will not perform as well as the r12 due to physical and chemical differences. The system needs a lot of air moving past the condensor to get the r134a to work properly. The first thing that may be causing problems is a worn fan clutch. They appear to work when visually inspected because you see the fan moving in response to changes in engine speed. However, a tired clutch will not spin the fan as fast as it should be going, thus, less air moving. At highway speeds this is not a problem but around town and at idle is a different story.

Secondly, most retro-fitters adhere to the adage of using r134a at 80% of the usual r12 amount. It has been my experience that a dual system Aerostar requires 56oz of r134a for optimal performance. Sounds like your system may be slightly underfilled. Ask the shop to add another 4 to 6 oz and see what happens.

How do you know which to do first? The best way to tell if the fan clutch is the problem is to have the AC shop connect the system to the gauges and wait unti the short cycle problem starts at idle. If spraying water on the condensor with a garden hose stops the short cycling, the fan clutch is the culprit. If no change is seen, then the system may be slightly low on refrigerant and adding the additional 4-6 oz would be warranted.

 

your low on freon. mine did the same think. added more freon and works normal.
you probably have a slow leak and lost some. these vans are very bad about leaking
freon. i have to add to mine all the time. the orings are what i think is leaking.
you might try some sealer in the system. it help alot with mine.

 

Well I found that the leak in mine was from where you put in the freon. It was leaking around inside the center of the stem. Went to the local tire store and got a couple of new center valves and replaced the one inside the high side and the one inside the low side.

 

pressure checked again a week later and pressures still good with no leaks....clutch fan was replaced about a month ago when installing new waterpump....now is there a orfice (sp) that need to be changed when converting from r12 to 134?...it seems when the compressor is running it really robs engine of power to the point of stalling it after about a half hour of driving ...

 

I've done the conversion from R12 to R134a on my 93 3.0L Aerostar. The orifice tube is the same whether it's R12 or R134a. However, there are different issues one must contend with during the conversion. Since I have no way of knowing what the shop did, and what they changed in your system, it's hard to say whether things are done properly. Here is my experience:

1) The old orifice tube was extremely dirty and had all kind of muck on the screen. Since it was very cheap (~ 5 dollars), I gladly replaced it.

2) The oil for R12 and R134a are incompatible, so you must remove all the lines and the condenser, and flush them out completely. The evaporator is hard to get to, so I just put some Polyol Ester oil (for R134a) in there and blew it out with compressed air.

3) The compressor and the dryer should never be flushed. For these components, I just remove them and dump out the old oil, pour in some ester oil and dump them again. Do that a few times and you would have eliminated most of the old oil. The residue won't hurt you.

4) On the compressor, there is a label saying how much oil one should add. Follow that guideline and use ester oil, add 1 ounce to the condenser, one ounce to the dryer and the remainder to the compressor, and assemble all the lines with new O-rings. The O-rings must be compatible with R134a, and you can buy them cheap at the local AC shop.

5) The system then must be evacuated and charged. As Aerocolorado said, poeple usually put in 80% of what is required for R12. However, my experience is that R134a requires a bigger condenser. If you use the same R12 condenser, there might be a problem charging it up to even 80%, let alone more than that. When I tried to charge up my system with R134a, the pressure relief valve on the high side (that contraption on the back of the compressor) was leaking due to excessive pressure build up. The reason is that the condenser was not working too well (just like Aerocolorado said), allowing pressure on the high side to rise too much. Imagine my surpise when I took a house fan and blew on the condenser. The pressure dropped immediately and the leak stopped. I ended up putting a small aftermarket electric fan on the condenser and wired it through a relay activated by the AC clutch. It has been several years and I never had any more problem with my AC conversion. From my experience, I can only advise you to try improving the air flow through the condenser. In retrospect, putting that electrical fan on was a lot of trouble. If I were to do it again, I would first try to eliminate the fan clutch completely. They do sell an adapter that allows you to do so, and it's the cheapest alternative. It might not be the most fuel efficient way to go, but it's the easiest.

Sorry for the long post, but I hope this helps

Regards

 

where is orface tube located. i would like to replace it like you did.
thanks for your help.

 

Warning: You must have a repair shop discharge your system before attempting to disassemble any AC component.

Disconnect the inlet line going into the evaporator (the lower one for my 93). The orifice tube is inside the evaporator's inlet, on the evaporator side, not in the line. Use a pair of small needle-nose pliers to pull it out. It might help if you know what it looks like, and the best way is to buy one before you start.

Good luck