Automotive Air Conditioning Information Forum

Trying to diagnose a 2010 Rav4 A/C problem. No power to switch. System is half full and from I read still should engage compressor. Have power at the pink wire(leading to ac on/off switch). No fuses blown, No power at pressure switch(switch has 3 wires). No power to compressor. Have connected direct power to compressor no engagement. Suspect bad compressor. This system doesn't have a relay, it has a ac amplifier inside of vehicle. Looking for info how to diagnose ac amplifier. Have replaced the on/off ac switch because it wouldn't ohm out. Shows infinite reading. Compressor switch shows 11.7 ohms for resistance which is correct.
Don't want to throw parts at it. Amplifier is near the $400 mark. Is there a way to do away with the amplifier? Install a relay? Then how would the rest of the controls operate?
Lost?
Mike

If the system is only half full of refrigerant, ~8 ounces net weight, the binary or trinary switch (the switch with the three wires connected to it) has probably opened because of low pressure. It's actually doing its job and not allowing the compressor to run under such conditions.

Before delving into all the electrical/electronic components (amplifier, clutch, etc.), first procedure is to recover whatever refrigerant is left in the system now (or have it done), evacuate for at least one hour, and recharge by weight with pure R-134a (without any sealer or other additives; fluorescent dye for leak-checking purposes is okay) to the specs appearing on the under-hood decal.

It's very unusual for a Toyota A/C amplifier to fail. In fact, I've never heard of one failing.

According to the specs that I have, this vehicle holds 16 ounces net weight of R-134a and 4.5 fluid ounces of PAG-46 oil (for both the 4-cylinder and 6-cylinder engines).

How many miles are on this RAV4, and to your knowledge, has the A/C system ever been serviced?

Are you saying 11.7 ohms for the compressor switch or the clutch coil?
I have never seen a clutch coil at more than 4 ohms, and 11.7 ohms for any switch seems high to me