I am a little confused... Just got done replacing a compressor, dryer, and orifice tube, flushed all hoses and the evaporator and condensor, blew everything out several times with compressed air, hooked up the vacuum pump and let it run for almost an hour and when I went to put in the new freon, it won't pull it into the system. Low side jumped up to 100psi when I opened the valve to the can and the high side is reading right about 100psi also but the freon is not flowing into the system.

Without tearing everything back apart, I thought I would check here 1st to see if anyone had an idea of what could be the problem.

Thanks in advance for any guidance.

Ray

PS. Yes I jumped the low pressure switch and the compressor is running.

 

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???

 

The compressor will suck refrigerant in only when it is engaged. If you're allowing the cycling switch to control the inflow, you have to be patient.

Continue to watch the high side pressure as it tells you more about the operation of the system than does the low side pressure. In a normally operating system, the cycling switch should close at around 45 psi ascending and open around 22 psi descending. When the refrigerant supply is connected, you're usually seeing low side readings that are pushed upwards due to the pressure of the supply can. High side pressure will typically run 175 to 250 psi when the system is properly operating. If you aren't seeing pressures in this range, you still need to let the system take its time and draw in more gas.

 

I am going to try and get it to take on the rest of the freon today and just be patient. Thanks for the advice. I will post if it resolves itself and ask for more ideas if it continues.

Thanks!

 

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!