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My AC goes on and off. I bought a new relay and put it in. The AC is still going on and off. I really thought it was the relay but it's not. Can someone let me know how I can fix it? Thanks
Last edited by mustfirst; May 6, 2020 at 09:19 PM.
The air inside the cabin is cold then warm, then cold again? Or the compressor is cycling on/off?
Yes, the vent is blowing cold air, then when i'm driving for a while, it won't blow cold air. But today it blew cold air all day, i drove for 1.5 hours round trip to work.
I'm not sure about the compressor thing, if you can explain i can try to find out.
When it is not blowing cold do you find that the air flow "strength" is reduced? Do you know what the ac compressor looks like and can you find it when you open the hood? If yes do this the next time it stops blowing cold. Turn off the ac , green light should go off. Open the hood and see if the compressor is running. The front of the compressor has a clutch and if the compressor is running it will be turning . Google auto air condition compressor if you are not sure to see what it looks like. If the clutch is engaged .meaning turning, then the ac control panel in the car is bad and needs replacing . The clutch should not be turning with the ac switch in the car in the off position ( no green light).
When it is not blowing cold do you find that the air flow "strength" is reduced? If yes do this the next time it stops blowing cold. Turn off the ac , green light should go off. Open the hood and see if the compressor is running. The front of the compressor has a clutch and if the compressor is running it will be turning . Google auto air condition compressor if you are not sure to see what it looks like. If the clutch is engaged .meaning turning, then the ac control panel in the car is bad and needs replacing . The clutch should not be turning with the ac switch in the car in the off position ( no green light).
When it is not blowing cold do you find that the air flow "strength" is reduced?
No
Do you know what the ac compressor looks like and can you find it when you open the hood?
Yes, i can try with some research.
Will get back to you in another day. it's cloudy and dark now. I will look at it when it's sunny.
Today I drove the car and it blew cold air all day. Same distance 1.5 hour round trip. So far it only stopped blowing cold air one time after I replaced the relay, that was just 2 days ago.
Ok , so next time if it is not blowing cold and if you can safely do so , turn off the ac , open hood and see if compressor turning. If it is turning with the ac switch turnrd off then as I mentioned before the ac panel is bad. Be safe
When it stops blowing cold air also check if the compressor is running when turned on in the cab. It should be on for ~10 seconds, off for ~10 seconds, then back on. If it isn't I would look at the compressor clutch. Over time the clutch wears increasing the gap. Eventually this gap becomes large enough to cause slippage which overheats the compressor. The compressor thermal protection then turns it off. Once cooled down (may take an hour) the compressor will work again until it begins to overheat. The clutch gap can be adjusted to fix this.
May 5th
I finished worked and was driving home. But I wanted to grab food and on my way to KFC the AC stopped blowing cold air, after driving for 15 minutes, started to blow cold again again for 5 minutes and then it stopped again. Picked up my KFC and on the rest of the way home it was not blowing cold air.
May 6th
Driving to work had no AC issues. On the way back I did the same trip as yesterday, on the way to KFC the AC started to blow air, not cold. After KFC I drove for 10 minutes on the local road before entering the highway and after 5 minutes on the HWY the AC started to blow cold air again. Very similar to yesterday.
It looks like the AC starts to work when I drive on the HWY.
I checked the compressor it spins only when i press on the MAX AC. It won't spin if I only press the AC or turn the heater on.
Anyone knows what is going on? Does the car need AC refrigerant?
Last edited by mustfirst; May 6, 2020 at 09:18 PM.
You checked if the compressor was engaging, you didn't check the gap or the system pressure.
If the pressure is right on the edge of too low the system can shutdown to avoid damaging the compressor. As stated previously if the compressor clutch gap is too large it causes slippage which overheats the pump. The pump has a thermal protection built in so it shuts off until it cools down to avoid damage, could be 15 minutes to an hour. I am 99% sure one of these is your issue.
You checked if the compressor was engaging, you didn't check the gap or the system pressure.
If the pressure is right on the edge of too low the system can shutdown to avoid damaging the compressor. As stated previously if the compressor clutch gap is too large it causes slippage which overheats the pump. The pump has a thermal protection built in so it shuts off until it cools down to avoid damage, could be 15 minutes to an hour. I am 99% sure one of these is your issue.
It looks like the compressor is not engaging. It was the hottest day of the year today. On my way back home the AC suddenly stopped blowing cold air. I pulled over on the hwy and did not shut down the engine. I opened the hood and inspected the compressor and counted until 10 two times but the compressor did not spin at all. It looks like the problem is the compressor.
I also think it doesn't need refrigerant otherwise it would not blow cold air occasionally.
You need a feeler gauge to check the compressor clutch gap. For the clutch gap measure the clearance between the rotor pulley (A) and the armature plate (B) all the way around. Should be between 0.35-0.65 mm (0.014-0.026 in.).
If the gap is too large (which I'm guessing it is) you can remove a shim to put it back in spec. You need a compressor clutch holder tool in order to get the center nut off.
Almost certainly didn't require a new compressor but at least it's working.
i just did the compressor clutch spacer thing. Super easy. Took about 45 min. AC blowing cold again. Had one spacer took it out. Took longer to tske the wheel well liner out.
