A/C stopped working - light blinking

A/C was working yesterday. 2009 taco with the V6 and automatic. I have never had any A/C problems with it before and starting driving it in the summer of 08, so it's 12 years old, and more than 100,000 miles now.

Today I start the truck and head out for iced coffee. Of course we are having out first head wave here in New Hampshire. Long before I get to the coffee, I noticed the A/C had not started blowing cold air. I then noticed that the A/C light was blinking.

Where I get to the coffee place, I googled it, and the first thread was from here and someone had fixed theirs buy just turning the A/C off and on again. They said it was the relay and when they replaced the relay the problem was gone for good.

So I turned it off and on again. The air started to cool off but then the light blinked again and the air got warm. So I tried it again. This time there was a noise from under the hood for a few, and the light started blinking again. Since then it has been the same result, weird noise then blinking light.

I'm a pretty good bolt turner and work well with electrical systems. But I am not a mechanic and I don't have all the tools to fully diagnose the problem. I'm guessing the weird noise was the belt slipping, but it was not a squeal.

What are the simple things to check before turning to a professional for help?

Thank you.

 

I would guess you have a leak and the low pressure switch shut down the compressor.

You should just take it to a ac shop and let a pro look at it. Eventually you will need to vacuum the system and recharge. But first they will need to find the leak.

 

I'm reading some other threads. It could be the clutch is not engaging, but that is still just a guess. It says you get a noise too when it is going out...

 

OK, as soon as I find someone to operate the switch, I'm going to watch the compressor pulley when it is engaged. Pulley still spinning - bad clutch. Pulley stops spinning - bad compressor. I hope it's the clutch.

 

When was the last time you used the a/c?

 

Yesterday. Cold air and everything.

I'm thinking the noise is not the belt slipping. That would be more of a squeal. If I can't come up with anything tonight i'll call around the shops tomorrow and see if I can make an appointment. Everything so far would be just a blind guess on my part. A real tech should be able to pinpoint the problem.

I hope it's not the compressor.

 

There is a 10A fuse and a relay for the AC. I believe both are in the engine bay. If the clutch is working the relay and fuse are fine. You should hear a click when it engages (i.e, when your helper turns it on). If that all checks out, it's time to get a pressure test.

 

A blinking AC light means one of two things. The compressor is not turning the correct rpm to match the engine rpm, or the rpm sensor in the compressor went bad.
Edit to add: If the clutch is slipping the rpms won't match.

 

I will have an assistant in the morning to press the button while I'm watching. I will be checking 3 things.

1) the fuse. I will pull it and ohm it out with my meter.
2) the relay. I will listen for the click.
3) the clutch. I watched some videos of them refilling the A/C. It seems you would need a working compressor to do this. The video showed what an engaged clutch looks like and a disengaged clutch. Basically either the center of the pulley spins or it does not. I will also find out where the weird noise is coming from.

If it is not obviously one of these 3 things, I am going to take it to a professional.

I also looked up some prices on Amazon. A whole compressor with clutch can be had for $200. A denso compressor is more and currently not available. I don't know which one I have, but the 2 parts do look different in the pictures.

They did not have the clutch listed as a separate part.

 

Testing with the assistant did not lead to any good new. Fuse and relay are fine. While the strange noise is from the area of the compressor, it is not the belt slipping on the pulley. The center of the pulley spun with the belt the whole time. I am unable to determine if it is just the clutch or the entire compressor.

I have an appointment at 2 on Monday.

Thank you all for your help. I will let you know the final outcome.

 

Let us know what it was after the diagnosis.

 

The tech found a leak at the condenser. The sound was either the clutch slipping from it failing, or the clutch slipping from the compressor failing due to lack of fluid. Recommended a new condenser and compressor. A new compressor comes with a new clutch.

They wanted 800+ for the compressor alone. I decided that I could sweat it out for a week or 2 more and ordered the parts on Amazon. I'm going to mount them and then have them vac it and charge it. I ordered all the parts with seals for around 350.

The tech also went around the car and did a pretty through inspection. Most were maintenance items that I knew about. Need new plugs, air filter, cabin air filter. But there were 2 items that needed more service.

The tranny fluid had been in there since I bought the car new. It was supposed to be lifetime fluid, or 100,000 miles. It had been 111,000 miles. I let them flush out the old fluid and fill it with new synthetic fluid. I also had him drop the pan an replace the filter. I did not want to do that on my own.

Also the front brake are wearing unevenly. He showed me a picture and one of the brake pads is not correct, it looks like it got hung up on one side. Recommended pad, rotors, and calipers. I ordered those parts on line today.

I hope to get it all installed and working so I can go up to Maine for the 4th. I was talking to the people with the brake parts, and normally they say it's about 2 days delivery, but with covid 19 all bets are off.