Automotive Air Conditioning Information Forum

BobbyZ wrote: Tue May 06, 2025 10:00 am Ambient temp 75, humidity 40%.
After car was warmed up, I revved the engine to between 1500-2000 rpm. Low side as 25, high side was 180.
Are my pressures in line. ?

Sounds decent; wait for temperatures over 75F and see if you and passenger are cool

GMBDguy wrote: Mon May 05, 2025 9:30 pm Should I just always replace the schrader valves on older systems while empty? Seems like its cheap insurance.

I would. Even though the cap is the "real" seal.

BobbyZ wrote: Tue May 06, 2025 6:03 am I just installed and charged a KIA K900 with two 12 oz cans of 134a and the readings I get are about 47 on low and about 147 on high side. This is with ambient of about 72 degrees.

Are those readings taken/measured at about 2000 rpm ? That is important information.

So I bought the FJC 2663 assortment which is normally $50 from JB Tools via Amazon. But they had one that had been returned. Normally, I don't do this, but the price was < $15 including shipping! So I took a chance... a couple of late-model GM cores were missing but everything else is there and ...

Disclaimer - I'm not an AC professional.

I'd like you to measure if the AC clutch is still getting 12 volts positive after the AC clutch disengages. This is a safer and better test than CAREFULLY tapping the AC compressor drive plate with a wooden handle to see if it then engages.

In 2019, I had ...

I'm not an AC professional, but good-working systems do not continuously build up high side pressure until the high pressure switch cuts off the voltage to the AC compressor. The high pressure reading will stabilize depending upon several factors, including ambient temperature, air flow over the ...

Flame Red wrote: Wed Feb 12, 2025 9:25 am I am well practiced now at replacing compressors and can do it record time

The goal is to do a job correctly, not in record time. You seem to be learning this.

Yes, that is a good time to add dye, add how much UV dye the label states, then add refrigerant oil to make up to that 1.5 oz. Then rotate the compressor drive plate about 10 revolutions by hand/wrench once it's all bolted up connected.

When my 1998 Frontier experienced similar symptoms about 2019, I tested it and found that when it wasn't cooling, the compressor clutch was not engaged but was getting voltage. For me the fix was to remove an AC clutch shim. Took me 30 minutes, didn't even need to remove my AC belt; and AC works ...

Cooling is achieved when the refrigerant changes from a liquid to gas form in the evaporator. Since the refrigerant is already in the gaseous phase in the evaporator, so a second evaporator in series would seem to be useless. At least that's how I understand things.