Friend recently purchased a 2003 K2500 Suburban. Bought with "AC needs a charge". The system is completely empty at this time. We were going to charge it with R134 with dye and stop-leak to see if we can either seal it up or find out where the leak is coming from. No immediate areas show signs of leakage, so it is possible dye was not previously introduced.

However, with the truck running and AC on we are getting 0V at the compressor. Relay in the engine bay is not kicking on either for the compressor (confirmed it is good). I disconnected the low pressure switch on the accumulator (with the tan tabs) and bridged them after confirming we are getting 5V there (which should in theory bypass the pressure switch). What else would prevent the AC system from sending 12V to the compressor? There are no fuses out - we checked all thoroughly with a multimeter for continuity.

Thanks in advance!

 

Low pressure switch is connected to the BCM or PCM which controls power to the clutch relay. Wiring diagram is needed.
To get compressor to run to suck in the home recharge kit you would have to jump the relay or put 12v directly to the clutch itself.
Don't use stop leak crap, it's bad and doesn't fix leaks at all.

 

Are you experienced with vehicle AC?

You stated "empty", but didn't state whether you pulled a good vacuum and then added R134a into that vacuum, that should supply enough pressure to turn the engine on and then the AC. If system was empty/down when you bought it, you would need a brand-new accumulator too.

Personally - I "chuckle" whenever I see an ad that states "just needs a recharge" because I KNOW that's not true.

 

Haha yes that's definitely true. "needs recharge" is ALWAYS indicative of another issue. Our intention was to get it running and then put dye in to see where it was leaking. You're correct in that I didn't put vacuum on it. Totally forgot as its been a while since I've had to charge a completely empty system. I have a vac pump and I'll put some vac on it and let it sit and see how bad the leak is. Worst case I can get some dye and refrigerant into it, find the leak, then repair and replace the spent components as well.

Thanks!

 

NEVER add any sealer or refrigerant containing sealer. Pure R134a and UV dye are OK.