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Jared D
Jared D, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1860
Experience:  Shop Supervisor at County Fleet
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2004 2500hd duramax. My a/c suddenly stopped working. I

Customer Question

2004 2500hd duramax.
My a/c suddenly stopped working. I jumpered the relay and the clutch is good. I switched relay with horn relay (which i know is good) and when i hit the a/c button in the truck it is not activating the relay.
Submitted: 1 year ago.
Category: Chevy
Expert:  Jared D replied 1 year ago.

Assuming that the AC is fully charged, it sounds like you might have a bad pressure switch. The pressure switch is supposed to tell the compressor when to engage as long as there is enough refrigerant pressure in the AC system.

You can test this by unplugging the pressure switch-the low side switch is located on the receiver dryer- and then jump the pins in the connector together with a jumper wire or paper clip. If the AC is set to on and the engine is running, the compressor clutch should cycle on. If it does, then the low side pressure switch is bad- or there isn't enough freon in the system.

Customer: replied 1 year ago.
I did actually try the jumper while the truck was running as well, kicked the compressor on but never got any cold air. Im going to have s friend draw the system down to check for leaks.
Expert:  Jared D replied 1 year ago.

If it ran the compressor but never got cold then I would say the issue is probably just low freon.

If you have a gauge set you could check line pressures and it would give you an idea of how much freon is in the system.

Expert:  Jared D replied 1 year ago.

Please let me know if you need additional information.

Customer: replied 1 year ago.
I have determined that the ac system has a leak. Cant hardly pull any vac at all on the system. How do i find the leak?