Bad AC?

My 4Runner is back, but the AC has ceased to work. When I turn it on, it works for about 20 seconds, then the button flashes intermittedly and the AC is non functional until I turn it off. The engine temperature is the same, I've had this problem before and the previous fixs (checking a thermometer sensor connection and topping off coolant) aren't working this time. Help?

 

Sounds like low refridgerant system pressure maybe?
Cars naturally lose a little bit each year. During the winter months or prolonged periods of non system use the orings between hoses and components shrink and harden and let a tiny amount out. Some cars seem to lose it a lot faster than others though. Ive had cars that never needed an evac and recharge and others that required a charge every couple years. Of course you could have a leak as well.
Im speculating on your issue as A/C diagnosis is futile over the internet but I am MACS certified for R12 and R134A certified through my manufacturer. If you decide to try an a/c recharge dont use that crap they sell at auto part stores as the propellant is mostly propane and who knows what else is in those cans. Take it to a dealer to have it looked at. I would GUESS your aux fan is weak/dead or low a/c charge but keep us posted. good luck!

 

I will have to check that out.

 

that isn't it unfortunately, the flashing light means the crankshaft sensor inside the compressor is bad. the flashing a/c light is to tell you to check if the engine belts are slipping or have the a/c system serviced.

I really wish Toyota never invented such crap but it reads the compressor rpms and if they don't match the engines rpms then it turns off the compressor to prevent damage. I have only heard of this with Toyota a/c compressors so I don't think anyone but Toyota uses these silly rpm sensors in the compressor.

the irony is, if you get a few too many miles, or years on a compressor and the sensor contact gets dirty or worn and then it doesn't read what it is supposed to and sends a signal to the ECM to shut the compressor off. so very often you have a perfectly good compressor with absolutely nothing wrong with it but since the sensor is built into the compressor, you have to replace the compressor to fix it.

my dads camry had this, its an 03 with only 18k miles yet he had to replace the compressor.

the only other solution is to jumper the a/c relay and install a toggle switch for it, but then if you do this the compressor never shuts off "ever" lol

sorry to be the bearer of bad news but if you have a Toyota, any Toyota, and the a/c light starts blinking and the compressor shuts off then you have to replace the compressor because a $5 part inside the compressor is bad and not reading compressor rpms properly. and this stupidity is to prevent a compressor from locking up and causing your serpentine belt from breaking on you lol

 

Did yo u ever resolve this

 

I have not, as a family friend has been driving it. I will try the sensor when I can however