Automotive Air Conditioning Information Forum

I have also seen fans that had gotten tired....spinning, but with little force....you have to check everything...

Good point about the electric fans.

You hadn't mentioned that the electric fan(s) were inoperative, JohnHere had to ask about that. We only know what the post author tells us ...

tbirdtbird wrote: Sun May 18, 2025 9:02 am Evaps are famous for leaks. It leaks when the comp is running because of the increased pressure.

Disclaimer: I'm NOT an AC professional

Wouldn't an evaporator have about 30psi pressure while compressor is engaged and static pressure of maybe 90psi when not engaged???

Did either of you read my post all the way through?
The first test of a new system is to see if the thing holds vacuum.

I need to pressurize the system with nitrogen. If I use shop air or add refrigerant prematurely I risk ruining the desiccant.

...

Yes, I used my Chemistry degree, Phi ...

Issue:
System will not hold vacuum, post-replacement. System equalizes from vacuum in just 30mins, which suggests (to me) a rather large opening... somewhere.

I realize that negative pressure indicates an opening in a system, while positive pressure reveals it. I lack the equipment to put the ...

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 ...