I swapped my motor a while back and since it was winter I didn't bother to put the AC belt back on. Now that it's warming up I put the belt on and it doesn't blow cold.

The system is charged, the AC light in the car comes on, but the compressor doesn't seem to be kicking on and the fan for the AC doesn't come on. From what I can tell everything seems to be connected, and the AC fuse in the car is good. I'm guessing I just overlooked something stupid. Anybody have a guess or a suggestion on what to check or where to start?

 

Is the compressor plugged in?

 

Yes sir, it is connected.

 

I don't completely remember the details of your setup, but a few pointers.

The light in the A/C button comes on independantly of the rest of the system. It merely indicates that the closure is getting as far as the switch.

The "A/C Amplifier" is the little box hanging on the evaporator- it's basically the "has this box frozen solid?" sensor.

The control signal goes into the ECU and the command to turn the compressor and fan on come out of it. Refresh my memory- was yours a parallel install or a standalone?

 

My megasquirt is a standalone. The AC was previously working with the megasquirt, for what it's worth.

 

Do you have R134 or whatever is proper for your A/C, in the system?

 

Yes, it's R 134a into a '99 miata.

 

I mean, do you actually HAVE any in? If not, the A/C won't start.