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Empty system not taking fill freon?

Ray(zr) on Sat September 11, 2010 8:40 PM User is offlineView users profile

Year: 90
Make: Ford
Model: Bronco
Engine Size: 5.0
Refrigerant Type: R134a
Ambient Temp: 90+
Pressure Low: 100
Pressure High: 100

OK, I am bit frustrated, replaced compressor, drier, and orifice tube with all new. Flushed all other components with solvent based flush. Blew it all out with compressed air for ~1 hour the hooked up the vacuum pump for almost an hour. Detached the vacuum pump and hooked up the can of freon and turned the engine on and jumped the low pressure switch.

Compressor is engaged but it is not drawing the freon into the system. Not sure why but the low side jumped to ~100 psi when I opened the valve to the can of freon and the high side moved slowly to ~100psi also but that is where it stays with the compressor running. The high side hoses are pretty hot and the low side is not really cold. Obviously the air vents are blowing hot air.

My first gut feeling that maybe I overtightened a fitting and caused the o-ring to squeeze into the hose blocking it? I don't even know if that is possible since the o-rings all slide onto a barrel that inserts into the female fitting so if overtight I would think the fitting would just leak.

Any suggestions, advice, guidance, etc... is greatly appreciated.


Too many trucks, too little time...

Ray(zr) on Sat September 11, 2010 11:02 PM User is offlineView users profile

OK - I have to admit that I found the original problem... The drier that I bought had a screw on cover over the port for the low pressure fill valve connection ( the other connections also) When I unscrewed the cover, I simply screwed on the valve fitting from my old drier that had a Schrader valve in it not realizing that the drier already had a schrader valve in the port already. Not sure why it was there since it would still need a connector port attached but that is why I was not getting any throughput on that side.

So I removed the Schrader valve from the drier and attached the low pressure connector with it's own Schrader valve and Voila! I had throughput. So I went ahead and re-attached the vacuum pump for another 45 minutes and then started adding freon (r134a). The first can added quickly and I attached the 2nd, it filled a bit slower but finally filled. When I attached the 3rd can, I reattached the low pressure switch connection. Now the system has quit taking on more freon even though I have around 2 lbs to go (total volume of 3.5lbs (56oz) based on what is published as the capacity and it only has around 1.25lbs (21 oz) in it right now. Why would it quit taking on new freon? I noticed that the low pressure side remained at around 25psi until the compressor cycled off then it rose up to around 75psi but as soon as the compressor kicked back on it went back down yet didn't seem to be actually feeding any freon into the system.

The air at the vents does seem a bit cooler but not what I was wanting expecting.

Any ideas???

Too many trucks, too little time...

1stbscout on Sun September 12, 2010 12:48 AM User is offlineView users profile

First things first. If you have already installed 2 cans that is 24 oz.
A 56 oz system should hold 4 cans plus 8 oz out of a 5th.
Is this an original 134 system?

If the system is cycling you need to jump the low pressure switch until it is full enough to stop cycling. Or you can take a long time to let it take in the remaining refrigerant. As the can gets cold, which it will do as it empties, the pressure in the can drops. You will need to either warm the can in some warm water or shut the valve off and wait for the can to warm up before trying to add more. Or just wait. It will very slowly take in the rest of the refrigerant.

Ray(zr) on Sun September 12, 2010 5:23 PM User is offlineView users profile

Converted R12 system with new compressor, drier, connectors, orifice tube, and liquid line. The 1st can lost a bit trying to fill it the first time and only had 11oz to begin with (1 oz of PAG in 1st can) so I am calling it around 9.5 ozs plus the 2nd can's 12 is why I came up with the 22.5 number.

I am going to try and jump the switch and get it to go ahead and take more today to see if that solves it.

Thanks for the advice and I will post if the problem resolves or ask for more help should it continue.

Too many trucks, too little time...

1stbscout on Mon September 13, 2010 12:00 AM User is offlineView users profile

this system will probably not hold the entire R12 amount. Watch your pressures and temps closely. Charge until the suction line at the accumulator is cold then check temps at inlet and outlet of the evap. When they are equal the system is fully charged. This may or may not be the same amount of R134 as R12.

Ray(zr) on Mon September 13, 2010 1:49 PM User is offlineView users profile

After some more troubleshooting, I found that the seal in the can tap was blocking the flow significantly and after re-seating the seal I also found the condensor wasn't getting enough airflow due to a aux tranny cooler that wasn't even connected anymore. I removed that, cooled the condensor with some water and the system is now fully charged. Going to also replace the fan clutch and have plans to replace the mechanical with dual electric fans soon. Hopefully this is now solved.

Thanks again!

Too many trucks, too little time...

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