Originally Posted by rpm5099

Did you make the changes yet? Mine has been working much better. In the summer when the heat load is higher I think you can get away with 14kΩ, but with low heat load I am pretty sure there will be freezing in the winter. Lower than 14kΩ doesn't seem to do anything but make it ice up on low heat loads.
The problem, I believe, is the integrated TXV without a sensing bulb. The temperature sensor is placed just after the TXV where the condenser is coldest, so even if the outlet is at 90F it's still going to meter the refrigerant. I guess it's a cheaper and simpler solution, but it makes me want to keep that variable resistor accessible and turn it down during the hotter months - I don't care if there's a little freezing on the first 25% of the evaporator coil.

Driving home on the highway on Sunday It was 90F with dew point of 83F (awful), and it managed to get the temperature down to about 58F on fan 3 setting (which was more comfortable than the fan on high because of the reduced humidity). Most of the cooling capacity in those conditions is lost to latent heat of condensation, the humidity kills A/C performance. The compressor ran continuously, like I wanted. With less humidity it's well below 40F unless the fan is on high and ices up on lower fan settings until I adjust it back up to 15kΩ or a bit more. I'm not complaining.

Originally Posted by averyislost

I had my AC condenser replaced because I went to get the refrigerant checked one last time, and they couldn't get it to stop hitting the high pressure cutoff and shutting down the compressor early. Said there was a restriction in the condenser. Surprisingly this made an absolute world of a difference. Afterwards, with the 15k ohm resistor the ac completely froze up on me 3 times on our 2 hour drive to the mountains. Outside air temp was 91 with 50% humidity. I had to keep manually turning off the AC to keep it from freezing, the vent temp was getting down in the high 30's. I couldn't believe it. This was with the AC fan speed on 1-2.

I've since moved to using an 18k ohm resistor and haven't had any freeze ups so far, and I'm getting mid 40's vent temps on low 90 degree days after about 10-15 minutes of the truck running. Still using the GX470 condenser fan for air movement at idle.

So at this point, my entire AC system has been replaced. Honestly the only thing that made a difference on mine was the condenser itself. And I had every little bent fin straightened out with the old one, and had washed it multiple times. Guess it really was just junk in the system causing an internal restriction. I'm guessing it was due to previous moisture in the system from the leaky evap core when I bought the truck.

Originally Posted by rpm5099

Wow, ok. I had already had my evaporator and condenser replaced, so it sounds like you did have a different problem. I'm surprised modifying the evaporator temperature reading made a difference at all with a blocked condenser, that's why I thought you were on the right track. I probably should have mentioned that you want to rule out restrictions in the system before going this route, but I guess at the end of the day you now have a way of making your A/C ice cold in the summer when you aren't worried about it icing up. Could be that I just have a drifting evap temperature sensor, but it never got very cold even with the previous evaporator and I would hope the new unit came with a new sensor (the one thing I did not do myself, was just too busy at the time).

I mentioned it in my original post but I probably should have called it out more directly - if you jumper that evap temp sensor with a 2kΩ resistor and the A/C goes from being coolish 55F to blasting ice cold air then your A/C is mechanically sound and the evap sensor is a potential culprit.

Glad you got it worked out!

Originally Posted by rpm5099

Based on your description that had to be the problem. I'm glad it worked out. Funny that you took out the resistor for the repair, you lacked faith!

I just used mine in the first hot weather and no question 20kohm is not enough. I'm going to install a variable resistor and adjust pedantically like a nut until I get the exact value for maximum cooling with no freezing. I've gone this far, might as well.

Onwon 20K Ohm Resistor 10 Turn Potentiometer 2W Wirewound Multi-Turn Adjustable Precision Potentiometer with 10 Turn Counting Dial Rotary Knob 6mm Shaft (20K Ohm) https://a.co/d/gh9Q00Q

Originally Posted by rpm5099

Wow, ok. I had already had my evaporator and condenser replaced, so it sounds like you did have a different problem. I'm surprised modifying the evaporator temperature reading made a difference at all with a blocked condenser, that's why I thought you were on the right track. I probably should have mentioned that you want to rule out restrictions in the system before going this route, but I guess at the end of the day you now have a way of making your A/C ice cold in the summer when you aren't worried about it icing up. Could be that I just have a drifting evap temperature sensor, but it never got very cold even with the previous evaporator and I would hope the new unit came with a new sensor (the one thing I did not do myself, was just too busy at the time).

I mentioned it in my original post but I probably should have called it out more directly - if you jumper that evap temp sensor with a 2kΩ resistor and the A/C goes from being coolish 55F to blasting ice cold air then your A/C is mechanically sound and the evap sensor is a potential culprit.

Glad you got it worked out!