No a/c...how do I test relays?
 

The ac in our 04 V6 runs fine in the morning, but starts blowing hot air once it warms up. I had the coolant filled yesterday and they said it was empty. I've checked the under hood and under dash fuses. The condenser lines were almost too hot to touch. I was going to check the relays next but I'm not sure how. I know there's am hvac self diagnostic procedure but I can't find the procedure for the dual zone system (with nav if it matters)

Thanks!

An a/c system in good shape will hold a charge for a very long time. If you had no R134a in the system, it likely means that you have a leak that you need to repair. Look at all connections through the system for signs of compressor oil leaking. It will be a dirt and oil mix on that connection.

Strange though how it's ice cold in the morning. The cars 7 years old with 140k. I'm taking it back over in the morning. Why would the compressor lines be so hot?

One line will get hot, the other line should be cold. Have the high and low pressures tested.

Did they evacuate the system and make sure that it could hold a vacuum?

Both are very hot. I'm not sure if they evacuated the system.

Try to find out how the a/c system was diagnosed and repaired by the shop that worked on it.

Your symptom of cold air for a short period, followed by warm air when vehicle warms suggests the compressor clutch is not engaging once clutch is warm.

A good test is to warm the car until compressor quits, and very carefully rap the clutch plate w/ a hefty stick. If the clutch engages and begins to turn, the diagnosis is confirmed: Clutch gap is too large and requires closing to enable compressor to run correctly.

Easy to say, but may be hard to do. If the compressor can be accessed and removed from mount or accessed from wheel well, it may be possible to remove the clutch plate (single 6mm bolt, 10mm socket), remove a shim from beneath the clutch plate and reinstall. Gap should be reduced to ~ 15-25 mils (0.015-0.025 inches).

If compressor can't be accessed, the system must be discharged, compressor removed to perform clutch adjustment.

good luck