The problem when the red compressor warning light trips is the A/C control unit is "seeing" a difference
in A/C pulley speed vs. engine speed. So, it shuts the compressor down in the event of the compressor ceasing. That way, if
your compressor ceases, you won`t shred the accessory belts or the compressor clutch.
There are four possible problems.
1)Compressor has ceased (doubtful) in which case you would have to replace it ($$$$$$$$!)
2)The pickup sensor on the A/C compressor is bad (speed sensor)
I would check this first because it is easy to check and the probability is pretty high. There are actually
two sensors on the A/C compressor that have to be replaced simultaneously (pickup sensor and thermal protector). Honda had
a recall on these two sensors. The new ones have a blue stripe on the connector. I believe they are only sold as a set anyway.
If you have a multimeter you can check the resistance of the sensors. You can disconnect them from the front of the car (radiator
opening, if I remember correctly). The pickup sensor (green wire and white wire) should have 450-600 ohms. If there is no
continuity, it`s shot. The thermal protector (red wire and brown wire) should have continuity (no specified ohm). You do not
need to remove the A/C compressor to change the sensors out.
3)The a/c compressor clutch is slipping and needs to be replaced.
4) The accessory belt that drives the compressor could be slipping and therefore tripping the warning light.
Does your belt screech when the compressor is turned on or shut off? Obviously, you would just replace the belt. If it doesn`t
screech, then I would look at the solutions mentioned above.
Please let me know if you need any more detailed information or procedures to do the job.
Alan (Alan SH/4WS)
1990 Prelude Si 4WS
2001 Prelude Type SH
