No ac
 

I have a 2002 Civic EX with 28,500 original miles. Not a typo. The ac has been working OK up until now. Turn the switch, will not go on. Had it checked and fuses OK as well as the blower motor and compressor OK. Seems to be definitely an electrical issue. Any ideas on this?

Not sure how those checks were done but I'd start by measuring the voltage at either wire of the pressure switch to ground. First unplug the switch and make sure it is closed (if not, there is likely no pressure in the lines because of a severe refrigerant leak, which is working as designed to shut down the compressor).

Then plug back in and start the engine for the voltage test. The voltage should be not zero with the A/C off and drop to less than a volt when you press the button. If that happens yet the engine won't idle up, also the condenser fans and compressor don't start, it's probably the MCU. MCU failure usually has other effects like the dome light and the keyless locks won't work either.

If the voltage doesn't change when pressing the button it's going to be either the control panel or the evaporator temperature sensor. Download the service manual and run the control panel self-test.

I'm not a mechanic on this stuff so I have to rely on a repair shop in my area to check this out. I will give them your suggestions. Thank you.

The rubber seals in the a/c system go bad if its not used often. This is why you're technically supposed to use it every once in awhile during the cold months. With your mileage, this is what i'd suspect. To protect the compressor, the a/c system wont turn on if you're low on freon.

Can't be. I live in south Florida.

mine wouldnt come on i changed the blower resistor in my 98 civic and presto back in business. btw what is MCU?

Turns out the problem was a defective fan resistor sensor. Denso 077800-0682