A/C quit working
- Thread starter Z71
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Papasonic
Active member
The AC quit working on our 2012 1.8 because of a faulty thermostat. a temporary fix to get it working again was to disconnect the battery for a few minutes, then reconnect. It may be a computer issue that prevents operation vs a refrigerant system problem. There are also relays that are in the circuit that may cause the compressor to not function.
Update: The A/C mystery solved!
Yesterday I drove the car in 90+ degree heat in city traffic with A/C on. The A/C suddenly quit working while I was sitting at a red light. I continued driving, the AZ/C came back on, then the A/C started intermittently going out. Several minutes later my coolant high temperature warning light and audible warning came on, so I immediately pulled over, turned the heater on full blast and let the engine idle for a few minutes to cool off. I noticed that the engine electric cooling fan was not on. Then I shut off the engine and opened the relay box under the hood and started checking the fuses. The 40 AMP fan fuse was burned out. I bought a replacement fuse in nearby auto parts store and installed it. The fan came on as soon as the A/C was turned on, but it cycles with the A/C compressor coming on and off. I assume that once coolant temperature gets so high, the fan will come on and stay on until coolant temperature drops below the threshold temperature.
It is obvious that A/C is automatically cut out by the engine ECU if coolant temperature gets high. This explain why the A/C shut of on me first time (original post) and why it worked flawlessly after the engine cooled off. The real problem was inoperable electric cooling fan (there is only one on this car) due to burned out fuse.
Yesterday I drove the car in 90+ degree heat in city traffic with A/C on. The A/C suddenly quit working while I was sitting at a red light. I continued driving, the AZ/C came back on, then the A/C started intermittently going out. Several minutes later my coolant high temperature warning light and audible warning came on, so I immediately pulled over, turned the heater on full blast and let the engine idle for a few minutes to cool off. I noticed that the engine electric cooling fan was not on. Then I shut off the engine and opened the relay box under the hood and started checking the fuses. The 40 AMP fan fuse was burned out. I bought a replacement fuse in nearby auto parts store and installed it. The fan came on as soon as the A/C was turned on, but it cycles with the A/C compressor coming on and off. I assume that once coolant temperature gets so high, the fan will come on and stay on until coolant temperature drops below the threshold temperature.
It is obvious that A/C is automatically cut out by the engine ECU if coolant temperature gets high. This explain why the A/C shut of on me first time (original post) and why it worked flawlessly after the engine cooled off. The real problem was inoperable electric cooling fan (there is only one on this car) due to burned out fuse.
Last edited:
minitrucking02
New member
outside air temp sensor is a primary input, if that is disconnected or faulty you will not have a/c
InfiniteHERO
New member
Smartdave
Member
I had the same issue... there are 2 fuses. Also there is a huge resistor mounted in the fan shroud. Mine was all corroded and broken. That resistor is what controls low speed fan operations. I ended up ordering a new fan assembly from rock auto
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Sent from my iPhone using Tapatalk Pro
A/c was intermittent on mine. Had the system charged/checked and worked well for a day, then on and off, then nothing next time in the car. Called the shop and told them I was bringing it back so they could see if their dye showed a leak, then when I started the car later in the day to go there, the AC blew very cold...
In the midst of all this, I replaced the thermostat. I was not getting a CEL, or any notable problems, but I wanted to replace it before problems in winter, as this usually fails allowing the engine to run to cool.
Told the guys at the shop this after they found no leak and measured by AC out put at 41F...
Possible explanation: Thermostat was allowing engine to run cool, so the radiator fan would not trigger, which reduced AC operation, since it is the only fan.
I did look at the fan connector and resistor (they look new) and at the fuse/relay box and saw no problem there.
If it goes out again, I'll re-check the 40A fuse and fan relay, but I think it was somehow thermostat related. I don't have a scanner, but after a few key cycles, the new thermostat probably cleared the errors and the AC started working.
In the midst of all this, I replaced the thermostat. I was not getting a CEL, or any notable problems, but I wanted to replace it before problems in winter, as this usually fails allowing the engine to run to cool.
Told the guys at the shop this after they found no leak and measured by AC out put at 41F...
Possible explanation: Thermostat was allowing engine to run cool, so the radiator fan would not trigger, which reduced AC operation, since it is the only fan.
I did look at the fan connector and resistor (they look new) and at the fuse/relay box and saw no problem there.
If it goes out again, I'll re-check the 40A fuse and fan relay, but I think it was somehow thermostat related. I don't have a scanner, but after a few key cycles, the new thermostat probably cleared the errors and the AC started working.
AC still not right. Cleaned condenser fins, checked all fuses and relays... really just acting like its low on coolant. Everything works, but its "cool" rather then "cold." Highway driving seems to produce better AC, compressor spins faster, I guess.
Going back to the shop on Tuesday.
Going back to the shop on Tuesday.
So dont know if anyone is still having this problem but my ac would cut out about 15 min after i started the car, disconnecting the negative cable from batter would reset it. One day, i have a stick shift, i turn the key off by accident and just turned it back on. 45 min drive home and the ac worked all of the way, now when ever i start it i turn the key off and on quickly and the ac keeps working. I think that there maybe some kind of time that is looking for a signal when the car starts and shuts down the ac if it doesnt get it but if u turn it off and back on before the car dies it doesnt know to look for it so the ac keeps working been doing this about a year.
Assuming the cooling fan works properly, the A/C compressor is working properly and the system is fully charged and there are no leaks, there are two sensors in the system whose malfunction can cause erratic A/C performance:
1. Temperature probe which is screwed into the A/C box left side inside the car and can be very easily replaced without disassembling anything. The cost is about $ 30 from a GM dealer. This probe turns the compressor clutch on and off depending on the A/C box internal temperature to prevent the evaporator from freezing.
2. Refrigerant pressure sensor is which is mounted in the A/C compressor line close to the compressor. It can be replaced without depressurizing the system because it has a Schrader valve. The cost of the pressure sensor is about $ 80 from a GM dealer. The pressure sensor also turns the compressor clutch on and off when certain pressure in the system is reached.
1. Temperature probe which is screwed into the A/C box left side inside the car and can be very easily replaced without disassembling anything. The cost is about $ 30 from a GM dealer. This probe turns the compressor clutch on and off depending on the A/C box internal temperature to prevent the evaporator from freezing.
2. Refrigerant pressure sensor is which is mounted in the A/C compressor line close to the compressor. It can be replaced without depressurizing the system because it has a Schrader valve. The cost of the pressure sensor is about $ 80 from a GM dealer. The pressure sensor also turns the compressor clutch on and off when certain pressure in the system is reached.
