I have a 2012 sonic 21k. Suddenly the AC began cooling slowly. I put a gauge on it and pressure was on the low side of normal when idling. It would jump to the high side of normal when you could hear the compressor kick off. I have never heard of freon increasing in a system so I added maybe 1/2 can. Now its worse. Whats up, anyone have any idea suggestions
AC problem
- Thread starter paul M
- Start date
Over pressuring will cause the system to shut down. Most newer cars have a "combination switch" that will open the circuit to the clutch at either too low OR too high a pressure. Also, only checking the low side pressure doesn't tell you the whole story. FWIW, you want to pay attention to the gauges when the compressor is running, not off. When it is off, the low side will spike and the high side will drop. When it cycles on, the high side should climb quickly and the low side should drop. I have no info on specs for this car, so I won't talk numbers. (I hate mis-information on the internets) It sounds to me like maybe your evaporator coils might be dirty, thus not a lot of cooling. It's also why so many people have issues with stinky a/c's in these cars. (including me.)
sonic_braaappp
New member
my sonics only a year old and blows nothing but hot air ._.
oldslowchevy
New member
Isn't that why we have cabin air filter? To prevent the evaporator from getting dirty.
No, I meant the evaporator coils. Oldslowchevy is correct, the cabin air filter is supposed to help this not happen, but smelly a/c is too common a problem on Sonics for there not to be a problem. It could also be the condensing coil, but I haven't read anywhere of people having that issue. I always try to learn from the misfortunes of others.
ChrisJ
Active member
I'm kind of confused by "the pressure looked normal"
Honestly, and this is going to come across as harsh, but if you don't own a manifold gauge set with both low and highside gauges as well as know basic refrigeration you shouldn't be adding 1/2 a can of anything to a system.
Something tells me you didn't purge the hose of air first either so now your system has air in it from the hose as well as moisture, which, hopefully the filter drier took care of.
If you feel there's a problem take it to a good shop. A\C is not a DIY hobby even though parts stores sell those awful 1 hose kits that in my opinion should be outlawed. They do far more harm than good. Unfortunately now, the only way to get that system right is to pull all of the refrigerant out, pull a good 400 micron vacuum on it and refill it with the proper amount of refrigerant. Technically you should change the filter drier as well.
Also,
The Sonic has a fixed displacement compressor which means on cooler days, or when you're running the fan on 1 2 or even 3 the compressor will cycle at times. That part is normal and when it shuts off your lowside pressure is of course going to go up.
My Sonic's A\C doesn't really shine unless it's around 90+ out and I run it on recirculate with fan on #4 and run the engine around 2,000 rpms. That's when it really performs nice. Othertimes, I deal with the temperature swings from the compressor cycling which is annoying, but the nature of the beast.
Honestly, and this is going to come across as harsh, but if you don't own a manifold gauge set with both low and highside gauges as well as know basic refrigeration you shouldn't be adding 1/2 a can of anything to a system.
Something tells me you didn't purge the hose of air first either so now your system has air in it from the hose as well as moisture, which, hopefully the filter drier took care of.
If you feel there's a problem take it to a good shop. A\C is not a DIY hobby even though parts stores sell those awful 1 hose kits that in my opinion should be outlawed. They do far more harm than good. Unfortunately now, the only way to get that system right is to pull all of the refrigerant out, pull a good 400 micron vacuum on it and refill it with the proper amount of refrigerant. Technically you should change the filter drier as well.
Also,
The Sonic has a fixed displacement compressor which means on cooler days, or when you're running the fan on 1 2 or even 3 the compressor will cycle at times. That part is normal and when it shuts off your lowside pressure is of course going to go up.
My Sonic's A\C doesn't really shine unless it's around 90+ out and I run it on recirculate with fan on #4 and run the engine around 2,000 rpms. That's when it really performs nice. Othertimes, I deal with the temperature swings from the compressor cycling which is annoying, but the nature of the beast.
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