JungloSonic
Member
2014 Sonic a/c compressor seems to go on and off at about 30 sec intervals. (30 sec on then 30 sec off then repeats). Does this indicate anything wrong with the a/c or is this normal. Outside temp was around 20 degrees celcius.
air conditioner
- Thread starter JungloSonic
- Start date
ozonetrooper
Member
The system has pressure sensing switches that tell it when the pressure is too high or two low.
The most common "trip" is the low pressure switch, which activates when the OAT (outdoor air temperature) is too low or when the refrigerant level in the system is low.
20 celcius OAT should not be tripping the switch, my guess is going to be it is low on refrigerant, meaning a leak in the system.
The most common "trip" is the low pressure switch, which activates when the OAT (outdoor air temperature) is too low or when the refrigerant level in the system is low.
20 celcius OAT should not be tripping the switch, my guess is going to be it is low on refrigerant, meaning a leak in the system.
JungloSonic
Member
how do I find the low pressure switch and if this has gone bad, it is a relatively inexpensive part. a/c works intermittently. when not working, gives misty warm air.
JungloSonic
Member
The pressure on the low side seems OK but fluctuates.
JungloSonic
Member
If the problem is more noticeable when weather is extra hot, then could it be that the coolant pressure is too high?
ozonetrooper
Member
What refrigerant is in the system ?
Have you put gauges on to monitor both sides for pressure ?
If the compressor comes on and the low side pulls below 25 psi and the compressor shuts down it may be the low pressure switch doing it's job .
If the compressor comes on and the high side goes to over 400 psi and the compressor shuts down it many be the head pressure switch doing it's job.
Depending on the refrigerant used, normal low side pressure is 35 psig, and high side is 225 psig.
Have you put gauges on to monitor both sides for pressure ?
If the compressor comes on and the low side pulls below 25 psi and the compressor shuts down it may be the low pressure switch doing it's job .
If the compressor comes on and the high side goes to over 400 psi and the compressor shuts down it many be the head pressure switch doing it's job.
Depending on the refrigerant used, normal low side pressure is 35 psig, and high side is 225 psig.
JungloSonic
Member
I have a gauge on my refill kit for the low side only and reads 40-60. Don't have means to measure the high side. coolant is 134A.
JungloSonic
Member
Today, when I arrived home, I checked the low pressure with a/c turned all the way up.
The low pressure side went from 50 (low end of yellow) to 75 (red) then something engages or disengages and it gradually goes to 50 psi. After hitting around 50 it gradually works back up to 75 and the cycle continues.
I wonder if I have too much coolant in the system?
The low pressure side went from 50 (low end of yellow) to 75 (red) then something engages or disengages and it gradually goes to 50 psi. After hitting around 50 it gradually works back up to 75 and the cycle continues.
I wonder if I have too much coolant in the system?
ozonetrooper
Member
75 psig is more than twice the pressure it should be running !
With the motor at a driving speed rpm the low pressure should be around 35 psig. Reading the high side is very important also, introducing non-condensables, (air) into they system will drive the high side up thus raising the low side as they work in conjunction of each other.
With the motor at a driving speed rpm the low pressure should be around 35 psig. Reading the high side is very important also, introducing non-condensables, (air) into they system will drive the high side up thus raising the low side as they work in conjunction of each other.
JungloSonic
Member
Should I reduce coolant on low pressure side and look for improvement. Is there a pressure level I should have on the low pressure side when car is not running?
ozonetrooper
Member
I would start with that.
If you look at the gauge, 35 psig for R134A equates to about 45 degree air temperature, ideal range for cooling. As the low side pressure increases so does the evaporator coil temperature.
If the suction pressure is double then more than likely so is the head pressure.
That would mean it is running over 450/500 lbs of pressure, thus causing the high pressure switch to trip out.
When the compressor is not running, (car on or off) the pressures should be equalized, meaning about the same on both sides.
If you look at the gauge, 35 psig for R134A equates to about 45 degree air temperature, ideal range for cooling. As the low side pressure increases so does the evaporator coil temperature.
If the suction pressure is double then more than likely so is the head pressure.
That would mean it is running over 450/500 lbs of pressure, thus causing the high pressure switch to trip out.
When the compressor is not running, (car on or off) the pressures should be equalized, meaning about the same on both sides.
JungloSonic
Member
When I initially turn on the a/c it works good for about 2 minutes. Then the compressor cycles on and off every 5-10 seconds. Does this first 2 minutes of running properly provide any more hints as to the problem?
When car was not running this morning, the low side pressure was reading about 70 psi
When car was not running this morning, the low side pressure was reading about 70 psi
JungloSonic
Member
Today I reduced the freon and the compressor was running consistently without going off but the air in the car was hot...So I decided to take to Jiffy Lube in Sardis, B.C. to have the system refilled properly. They told me that there might be a slight leak in the system but refilled it (They said that the leak must be small that their machine didn't catch it so it's OK to use as is). They also said that the big fan at the front (by radiator) was not working. I asked them why the mechanic had hooked up wires to the fan for testing without checking with me first..They didn't have an answer. I have seen the fan working previously. Now they want to charge me to do a a diagnosis if I want them to do it. The fan can be turned freely by hand so it is not sized. Any suggestions?
JungloSonic
Member
Well. I myself hooked up wires directly from battery terminal to the radiator fan and what do you know...the radiator fan works. Any idea what I should look at next to figure out why the radiator fan is not being activated?
Thanks.
Thanks.
JungloSonic
Member
Is there a way to test if the car is recording correct temp and will run the fan when temp reaches the threash hold. I don't want to run the engine until temp light in dash goes on and damages my engine.
ozonetrooper
Member
Let's start over. The ac compressor was most likely cycling because the fans were not coming on. Refrigerant pressure is related to temperature and both sides are bound by the science. If one side is high because of no fan operation so will be the other, thus the readings you were getting.
The fan has a low and high speed relay as well as a fuse, all of them must be checked to determine where the problem is.
The relays can be bad or not being told to run the fan, you must determine which is the issue to diagnose.
The simple fix could be a burned out fuse. that is where I would start ...
Really sounds like, you need to let someone who knows what they are doing to work on it, in IMO.
The fan has a low and high speed relay as well as a fuse, all of them must be checked to determine where the problem is.
The relays can be bad or not being told to run the fan, you must determine which is the issue to diagnose.
The simple fix could be a burned out fuse. that is where I would start ...
Really sounds like, you need to let someone who knows what they are doing to work on it, in IMO.
JungloSonic
Member
You are soo correct. last night I saw this YouTube video sent to me by someone who knows a bit about cars.
ave
There was a 40A fuse that looked fine but when I replaced it with another, the fan is coming on and the a/c compressor is not cycling rapidly. Everything seems to work OK.
I have probably driven many miles without realizing that the radiator fan was not working as I have been dealing with rapidly cycling compressor for some time now while I have been driving the car. Have I done much damage to the engine?...I don't recall the temp light ever going on and I have no codes when checked with ODB 2.
ozonetrooper
Member
If the temp light never came on I see no reason that any damage has been done.
JungloSonic
Member
I believe the Sonic Radiator fan runs at low speed and high speed. Low and high speed both have their own pathway ( fuse and relay). Since I replaced the high speed fuse the radiator fan started to run but before that, the fan did not work..Not even at low speed as far as I could tell. Could there be a problem with my low speed pathway as well (fuse, relay or wiring) ? If low speed pathway was good should it not have been running at low speed all the time when the high speed fuse was dead?
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ozonetrooper
Member
Lots to that question !
The speed "call" is determined by the sensors, which then tell the relay to engage and that in turn runs the fan.
You need to determine if you have a "call" at the low speed relay. If you do and then check to see the relay is working.
If it is then check to see why the fan is not running in low speed at the fan .
The speed "call" is determined by the sensors, which then tell the relay to engage and that in turn runs the fan.
You need to determine if you have a "call" at the low speed relay. If you do and then check to see the relay is working.
If it is then check to see why the fan is not running in low speed at the fan .
