I'm hoping someone can help me figure out what exactly is going on with my car. I've been having issues with the AC for what feels like forever.

At some point 3 years ago my AC compressor pooped out on me. I had this replaced 2 summers ago but had issues with the air not being as cold as it should've been. The mechanic that put the new compressor in didn't know what to do but I went on a road trip where the radiator died on me. Replaced that.

Last summer, we started hearing a "knock" coming from under the hood on the passenger side and then the entire car would start shaking violently. The some-what "cold air" ended up just being uncomfortably warm/hot air and the temp gauge would rise & the RPM's would "jump." Felt like power surges. We ended up replacing the radiator fan and the issue seemed to stop.

Well now the condenser fan had gone out so we just replaced that last night. The air is significantly colder now and I couldn't be happier. But.. when in traffic or parked, the fans will sporadically turn on/off and the air becomes uncomfortable warm again. When the AC is on, both fans come on but it's like the fans don't know when or how long to stay on.

I was planning on replacing the ECT sensor but I a) have no idea what I'm doing/what to search for/pulling my hair out and b) after finally finding the attached diagram, I'm not sure to replace A, B, or both? Also.. is a switch and a sensor the same thing?



I forgot to add that the car isn't actually overheating (from what I've experienced so far with the new condenser motor) but the fans are definitely having issues. What about the relay? I don't have any idea. Any help is appreciated! I'm moving in a few days and REALLY want to get this fixed ASAP! Thanks in advance!

 

Just went out there and messed with the car in the driveway. With AC off, both fans are off. With AC on, both fans turn on. After about a minute, both fans turn off (AC still on). Then both kick on, both kick off, both kick on, etc.

 

can you check and see exactly what the compressor clutch is doing at the times the fan is turning on and off ? is the compressor cycling on and off at the same time ? Is it turning on at all ?

 

After like 6 hours of searching, I think the system is overcharged and has been since the day the new compressor was put in (My neighbor did it. He was supposed to be a mechanic but I think he was in over his head...) The pressure is way too high so it's cutting the whole system off. Should I just take it to a shop and let them fix it, or is this something I can do at the house?

 

You can buy a set of manifold gauges from Harbor Freight and check it yourself. After using them you can return them for a refund minus the restocking fee.

 

if i was you then i would take it to a garage that has a A/C machine that can properly recover all of the refrigirant and put the right amount back in it with no problems to save your worries.

 

I checked the pressure and it was way out of range for what it should be. So now it's 25 psi and running a LOT better. The car used to shake like crazy when the AC was on but now not so much. After a while of driving around, I noticed the fans (both) still turning off. This may be a dumb question but if they turn off when the pressure is too high.. do they turn off if it's a little chilly outside? I thought the cooling fan was supposed to be on when the AC was on until I shut the car off?

 

if memory serves me correct then when your a/c cycles off, so does your fans, your cooling fan turns off and on due to engine coolant temperature. your a/c compressor cycles on and off to keep the air in the car cold at all times, if the air is getting too cold then the compressor will cut off the keep the lines from freezing up and when it gets hot enough again then it will cycle back on.

 

If they are turning on and off exactly when the compressor does then I think it's safe to say they are doing what they are supposed to be doing.

I actually have a leak on my low side valve so I can't check if they turn on turn off with the compressor or I would check for you.

 

yes they are operating correctly.

 

The weather was finally warm enough to see how the AC can handle the heat. The "knock" from last summer is back. It comes from the passenger side. It knocks and then the fans kick on. Then the fans go off a few seconds later, knock, come on, go off, knock, etc. So.. I'm not convinced they're operating correctly. >_<