Living in phoenix A/c is a necessity. However my Mustang begs to differ.

If you've read my other posts, the Heat works great and cool air...well not so great.

So I bypassed the heater core today and went to fire up the A/C system. It went good until the Compressor started to cycle. 3 seconds on, 15 Seconds off. I bought a low pressure switch and that is not the problem. What else could it be? I need to have A/C today!

There is a multi function relay that sits behind your coolant resorvoir in the engine bay. It controls the fan, compressor, fuel pump, etc. Looks like a black metal box with 2-3 screws and a connector with wires going in it. Looks like a mini ecu. My air stopped working and I unfortunatly had to pay a guy $40 for him to tell me the relay was bad. Wanted a $100 for a new one, found one in a junkyard for $10. Air works fine. Might be worth trying.

You might need your refrigerant updated or you might have a coolant leak.