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Bon soir. Comment ca va? If you are sitting in the driveway with high RPM is it still cold? If not then “AC is blasting cold only when the engine operate in high RPM” is not true. Does the vehicle have to be moving fast to get the AC working? If yes then check to see that the engine cooling fan(s) (not the A/C blower fan) are on all the time when the AC is turned on. They should be on constantly when the AC is turned on.
I know eh… I’ve seen Eric video and I thought to myself: Why haven’t I asked him sooner?
Now that you talk about it, the safety switch that shut off the compressor to prevent damage make sense… As is clearly stop and kick back on a few second later… It is still blowing cold air, (intermittent of course) that’s why I have doubt on the compressor being dead. He clearly told me that I needed a new one…
When the car was new I could let it sit with the AC ON and it was blowing cold. I haven’t try to rev up the engine when it’s sitting in the driveway. I’ll try that tomorrow.
+1 on checking the fan if it is working or not. and check if compressor is getting proper power.. and fuses. My own Jetta actually had a bad fuse that was slowly giving out. I have never seen such a thing.. most fuses b
hmmm… I would ask what was the PSI readings of the Low and High lines to confirm leak. Second.. if something is dead… DEAD! why would it kick off for a few seconds then back on. I am confused but I wouldn’t say it was ‘dead’
You probably do have a leak. And if the level of Gas has dropped enough the switch on the line will stop the compressor from kicking on. Safety switch basically to prevent damage to the compressor. I’d take it to another tech to confirm before you put money into it. There are a few things to really check before condemning the compressor.
Eric did a recent video on A/C. Worth checking out for sure.
If you rotate the end of the compressor with the engine off of course it should spin freely, with out coming to a stop or feel like it is hanging internally. If you can also rule out that the compressor itself isn’t leaking and there are no clutch problems your compressor should be fine and I would not replace it.
I would first check to see if the a/c compressor is actually engages, just so you know for sure. If it is, I would check to make sure your fan is turning on along with making sure there aren’t any blockages at the condensor. If the a/c is still not working with the compressor engaged, fan on, and no blockages I would say you have a leak somewhere, enough pressure in the system to allow the switch to send power to the compressor but not enough to allow the system to cool properly.
When the engine is at “higher rpms” is that going down the road or sitting still? If the system is weak with the extra air being pushed through vents while going down the road could cause it to feel cooler. Putting a thermometer in the vent when it seems as though the a/c is working wouldn’t be a bad idea as well because it will actually tell exactly what the temperature because just feeling the air can be miss leading as to how cold it is actually getting.
Ok so I did some testing. After work I parked the car home and got to eat, the car sat about 45 minutes and was still near 90 celcius (194 fahrenheit). I started my car and turned the AC to the max, the fans comes ON and I had cold air right away! This morning, I did the same, I started the car, turned the AC ON, same things, fans comes ON but no cold at all, I’ve let it idle about 5 minutes and reved it to 2000RPM, still nothing, leaved for work, I had cold air about 15 minutes after I leaved… I don’t understand, AC work when the engine is hot but not when it’s cold… My intercooler/radiator are cleand and free from debris so the air flow no problem. I’m lost, anyone have ideas?
It probably has a leak and the coolant is low. I would take it to another mechanic and see what he tells you.
It could be the refrigerant is low as suggested, checking the fan operation was a great start. The only real way to diagnose at this point would be to check the operating pressures to verify the low refrigerant. AC work is often hard to diagnose even for a professional so in the end you may need to take it to someone that is fluent in AC work to have it diagnosed at the very least. Keep us posted on your progress however.
As others have said , check your pressures. It’s not a difficult job to check them yourself with a manifold gauge and hose set. Eric’s has good video’s on AC systems.
My two cents … I had a 95 Honda Accord and then a 2000 Jeep Wrangler that both had the symptom of the AC working for a few minutes then not, then working, then not. A repair shop told me I needed a new compressor each time ($$). These were old cars, and honestly, I don’t use AC that much in the Jeep anyway. With a little research, I found that compressors have electro-magnetic clutches and the gap can become too wide for the magnetic field to operate consistently. The good news is that you can remove a shim to get it working successfully (I was able to do this on both vehicles without disconnecting any lines). Check a shop manual for your vehicle to find the correct gap.
+1 with the gauges. You also need to know how to read them also.
Do you have any issues with icing on any of your A/C lines?
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