Ok, I live in Oklahoma which gets super hot and muggy this time of year. My Aerostar is my wife's van which she transports our 2 small children in all day.

Well, here's the prob. I converted to r134 last year. Vac'd out the system and kept -15psi on it for 10 minutes. I used freon w/oil at least 3 cans of it when recharging. It cooled at it's lowest 53 degrees. Which was fine with us. Well w/in 3-4 weeks, it wasnt cooling down anylonger and at that time with summer almost over, I didnt bother to check into it.

I repeated the same process last week but, I did find that a vacuum hose leading to the carbon cannister was disconnected. I repaced the vac hose and reattached it. Vac hose was replaced b4 recharging system. Anyway, after charging system it cooled beautifully again. We did however notice that the system had basically full pressure b4 we vac'd it out. Well, this time the cold air only lasted for 3 days before going warm. The system has a little over 100psi and you can push the valve in on the hp side and it shoots out freon. I see nor hear any signs of leakage. My compressor is alittle noisy but a mechanic buddy of mine says thats a common noise and not to be worried.

My wife is getting onto me here about this so if I could get some good advise quick, aaah man that'd be like water in the desert for me right now. = )

 

There could be any number of reasons for these problems. Based on just your description of events (loss of A/C after 3 days) it sounds like you have a leak in the system. You can rarely hear a leak. Fresh oily residue around a fitting is visual evidence of leakage. You can purchase leak detectors or have a shop scan for leaks. Other causes include under/overcharging the system, bad low pressure switch, compressor clutch failure, plugged orifice tube and weak fan clutch. If you have a set of gauges knowing what the readings for high/low sides and ambient air temperature would be a place to start - assuming there is no leakage. My advice would be to first replace all the o-rings in the system with new, nitrile ones, replace the orifice tube at the same time and then try recharging using a set of gauges. Compressors normally do not make noise unless overcharged or worn out. If the orifice tube screen is covered with blackish particles, you will need a new compressor pronto.

 

Thanks for the prompt reply Aerocolorado.

2 things though:

1. I still have over 100psi of pressure and it's warm air blowing out.
2. What and where is the orifice tube located?

Is it the fact that once the seal is broken causing leakage that outside air is sucked in nullifying the whole system or what?

 

Is The 100 psi on the high side or low side, and with car running or off?

 

It's on the low pressure side with van running.

 

Ok that presure reading is way to high. First thing I'd check is whether or not the fan clutch is engageing. Second of all I'd check the condensor to see if there is crud caked in and arround it stoping the flow of air through it. If both of those are good, I'd check the low side cycling switch or just replace it. If nothing there I'd check to be sure the compressor clutch can disengage. Hope this helps. BTW low side pressure when running should be somewhere between about 26psi - 40 psi if I remember right.

 

I did have a slight leak on my low pressure side and Ive spliced a hose coupler in. Hopefully it'll hold pressure. Im going to put another vacuum test on it tomorrow.

BTW, my compressor has a clicking noise when engaged. AeroColorado told me what to check but, where is the orifice tube so I can check the screen for particles? It's a 92 3.0 V6 XL.

 

You'll have to depressurize the system to get to the orifice tube. It's located inside the inlet of the evaporator. You can use a small pair of needle nose pliers to pull it out .... very gently. If you have dual air, change both

By the way, when you convert, did you get rid of all the old oil completely. And I mean completely! Blow it out of the evaporator, drain the receiver, drain the condenser and the line, drain the compressor, etc... Everything has got to be flushed and drained (do not flush the compressor and the receiver though, just drain them). Then you meter into the compressor exactly the amount of oil that the label on the compressor tells you too. Use Polyol Ester oil and new O-rings. Aerocolorado said something about nitrile O-rings. I thought nitrile meant Buna-N (the black looking type) which is only compatible with R-12. The green ones that Ford uses are either Neoprene or Viton which is good for both R-12 and R-134. But then, I could be wrong, so check with the local A/C shop, they will tell you, and sell you the O-rings too.

From the symptoms you described, it seems you have way too much oil in your system, and you Fan Clutch may not be working too well. You need a new fan clutch too. Otherwise, you might be leaking R-134 through the safety valve in the manifold bolted to the back of the compressor when the condenser cannot keep up in hot weather.

Good luck