I'm working on my sister's 1987 Toyota 4Runner which she has had since new. I can't get 12V power to the A/C compressor. The push button switch on the dash lights up when turned on. There are two fuses and a relay behind the radio to the left of the glove box. If I pull the one fuse the light on the A/C button goes out. If I pull the relay the light goes out and reinstall it the light comes back on with a click from the relay. If I put 12V power to the compressor it will engage the clutch and the air blows cold. I put my A/C gauges on it and it shows good high/low pressures when I make the compressor run by directly giving it 12V. I just can't get 12V to the compressor wire from the system. Could this relay still be bad? Is there another relay? Where is the switch that tells the compressor when to turn on or off? I know on my Ford Bronco it's on the side of the accumulator/drier but I can't find it on this 4Runner. I was tempted to just install a off/on switch for the compressor to get her thru the hot weather but I was afraid she would forget and leave it on when she shut the truck off. Thanks now for any information.
87 4Runner A/C clutch won't engage
- Thread starter gov2mod
- Start date
Register to hide this ad
Is that the correct relay for the A/C compressor? The one behind the radio had 5 pins while the replacement one I looked at on the Autozone site has four pins. While it made the light on the A/C push button go out when removed, is that the correct A/C relay and if not where is the four pin relay located?
Black_TurboSR5
New member
A lot a AC systems will cut out power to the compressor clutch is the freon is too low or empty to keep it from over heating. If it is empty and you start adding a can of freon the compressor clutch will usualy engage after more than half a can is in the system.
Thanks, I already tried that. Plus I put my gauges on it and it had good pressure. Of course I had to put 12V directly to the compressor to make it run while I had the gauges on it. When I put the 12V on it it does blow cold air but I don't leave it on long as it won't cycle and I'm afraid it would built up too much pressure.
Black_TurboSR5
New member
Pressure sensors? There may be two one by the dryer and one by the condenser in the front.
