SPF GT40 A/C Refrigerant Capacity?

#4
Rick,
I have installed your A/C seal kit. Charged the system with 32 ounces, but not getting the kind of vent temps I expect. Pressure readings are good - ~25 psi low side, ~175 psi high side. I would expect something in the 40 or 50 degree F range on air temp coming out of the vents, but still getting around 70. What is your experience, please?
 
#6
Two other things to check. Is the pipe between the expansion valve and the evaporator cold when A/C running? Also some units have an adjustable thermostat on the side of the evaporator box. It's a brass vertical rod tucked away inside the 'pod' on the side. A little hard to reach, but it can be turned for adjustment.
 
#7
Thanks, Dave. No leaks - can pull a vacuum to ~30 inches and close it off for the night. Next morning, still tight. I'll check the other two things you suggested Friday and report back. Appreciate the help!
 
#11
Update: This thermostat is adjustable. I was able to turn it clockwise, about 90 degrees to the hard stop. Turning it the other way to the hard stop (CCW over 1 full rev) resulted in the compressor NOT turning on at all. Went back to the full clockwise position. Filled with 32 oz R134a, but vent air temps still only about 70-75 deg F.

Thoughts? Should I try to get a replacement thermostat? The evaporator is producing a good amount of water and the lines between the expansion valve and the evaporator are cold. I'm talking in the 50's with a infrared gun thermometer. Perhaps that's not cold enough.
 
#12
I'm not an A/C expert, but a couple of suggestions:
Your thermostat sounds OK. Was your A/C working OK before you refilled it? Are the 3 A/C control knobs in the door panel set right? Try different combinations as SPF labeling was not always correct. I tested my expansion valve to evaporator pipe and initially got upper 30's. However after just a couple of minutes underhood heat raised that to upper 40's. If none of this improves things I would suspect moisture in the system. You can get normal pressures and still have moisture. Did you use refrigerant cans to fill? Did you purge the manifold line to the can each time you started a new can? Finally replace the drier every time pressure is lost or lines are open for more than a few minutes.
 
#13
A/C was never very cold. I will try different combinations of the control settings, but I believe I know exactly the functions. I'll try changing the dryer. Yes, on refrigerant cans to fill and yes on purging the lines each time. Having just finished an aftermarket A/C install on wife's '55 Thunderbird, I feel good about my recharging process. Just can't seem to get the temps I expect.

Thank you for the responses!
 

Randy V

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#14
Drier is what I would suspect. That and their’s a little inline filter screen on most systems that can plug up with chaff from hoses or compressor if it is going out. That will reduce the flow of freon substantially. One other thing would be too much oil in the system. If you have not had the system evacuated properly, it would be a good idea when you replace the drier..
 
#16
Is there a OEM/late model drier cross-reference? I love going to Advance Auto Parts and hear them ask, "What car are you putting the drier in?"

Where's the filter you mentioned, Randy? Also, I'm not adding oil at all. Just refrigerant. The compressor came oiled from Roush.
 
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