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Wonky fans and no AC


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13 replies to this topic

#1 provin1327

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Posted 07 May 2014 - 04:15 PM

1996 Impreza 2.2L 5 speed. The A/C has not worked since I bought it, it just blows warm air. I took a look under the hood and noticed the clutch is not engaging. I pulled the fuses and relays and they look fine. Will the compressor not turn on if it is low on freon in an effort to protect from damage? I pulled both the high and low pressure caps off and poked the schrader valves. A bit of gas did leak out so I know there is some stuff in there. I have not gotten the multimeter out to test for voltage.

 

Second question, my fans turn on and off mysteriously when the key is in the "on" position. Not sure where to start with this at all. The fans seem to be running properly under normal driving conditions.

 

Here is a video showing the wonky fans

 


Edited by provin1327, 07 May 2014 - 04:33 PM.


#2 Fairtax4me

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Posted 07 May 2014 - 06:47 PM

Poke under the dash in the drivers side and disconnect the bright green plugs. That's the "test mode" plug for the ECU and it makes all the relays and solenoids cycle.
This may affect operation of the AC, not sure though.

Most commonly the pressure is too low in the system. There is a pressure switch which keeps the compressor clutch from engaging if the pressure is too low or too high.
Leaks at the o-rings on the compressor are common. Look for greenish oil on top of the compressor.

#3 provin1327

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Posted 08 May 2014 - 12:30 PM

Im not seeing any leaks or fluid anywhere.

Edited by provin1327, 08 May 2014 - 01:01 PM.


#4 provin1327

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Posted 08 May 2014 - 01:01 PM

Well I feel dumb, the fans are just doing a self test, everything is fine there. As far as the AC goes I am not getting voltage to the AC but I jumped the clutch and it does engauge. I do have continuity at the pressure sensor so I know it is not the sensor that is shutting off the system

Edited by provin1327, 08 May 2014 - 02:40 PM.


#5 willwright

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Posted 08 May 2014 - 04:13 PM

Most likely low on freon. Has to have enough pressure for pressure switch to send voltage to the clutch switch. You can pick up a cheap gauge at any parts store or even some cans now come with a small gauge. They won't read high side pressure but will read low pressure side which is good enough for general recharging if you have a slow minor leak in the system.

#6 provin1327

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Posted 08 May 2014 - 11:10 PM

So I know the dash switch works because when I switch it frmm AC to Max AC the fan blows much harder. I am hoping its just low freon and has been low for a while which is why there are no visible leaks, going to buy a can and recharge it tomorrow

#7 Rooster2

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Posted 09 May 2014 - 10:01 AM

So I know the dash switch works because when I switch it frmm AC to Max AC the fan blows much harder. I am hoping its just low freon and has been low for a while which is why there are no visible leaks, going to buy a can and recharge it tomorrow

Yea, sounds like low on refrigerant. You may have a slow leak, but not terribly bad, if some refrigerant is still in the system. System holds 2 cans. Adding one can may not be enough. Be sure to add refrigerant at the low port. It will prolly have an (L) embossed on the port cap. I know mine does. When adding 134 turn on A/C, set fan on high, and dash slide lever to coldest position.

 

Let us know if this works.



#8 Fairtax4me

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Posted 09 May 2014 - 10:16 AM

So I know the dash switch works because when I switch it frmm AC to Max AC the fan blows much harder. I am hoping its just low freon and has been low for a while which is why there are no visible leaks, going to buy a can and recharge it tomorrow

All this does is change the air diverter flap from fresh air to recirculate. It starts pulling air from the floor area inside the car rather than through the cowl vents outside. Makes a shorter path for air to et to the blower motor, so you get better airflow. Really has nothing to do with the operation of the compressor.

#9 provin1327

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Posted 09 May 2014 - 10:19 AM

So its possible that power still isnt getting to the compressor even though the switch is flipping between the two AC modes? If I have continuity at the pressure sensor when the Subarubis running and the AC is flipped on doesn't that mean I have pressure in the system? If it was low on freon the pressure sensor would not have continuity right?

Edited by provin1327, 09 May 2014 - 10:19 AM.


#10 1 Lucky Texan

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Posted 09 May 2014 - 10:33 AM

many electrical control systems are 'normally closed' (that way, an open wire or connector will trigger an inspection/repair) so, it may be that you're right, IF that is the only sensor controlling the system. But, there's an overcharge sensor too i THINK. And, there could be a relay that's bad-or a fuse. Fuses can be confusing on visual exam - ohm it out. And try a new relay - swap with another if you have 2 that are the same.


Edited by 1 Lucky Texan, 09 May 2014 - 11:00 AM.


#11 provin1327

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Posted 09 May 2014 - 10:36 AM

If I unplug that sensor and jump it and the clutch engages then I know its the sensor. I havent checked any of the relays yet but the fuses are good.

#12 Fairtax4me

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Posted 09 May 2014 - 11:17 AM

The compressor should be engaged when the selector is on any setting that uses the AC.
There are several relays and switches in the way between the control panel and the compressor, so yes even if the pressure switch shows continuity power could not be making it to the compressor clutch due to one of the other switches or relays.

Obviously make sure all the fuses are good first.

Power for the compressor clutch does not flow through the pressure switch directly. Power for the compressor clutch comes from the ignition switch, through a fuse in the AC relay holder, through the AC relay, through the compressor thermal switch (if equipped), then through an AC cut relay, then to the clutch.

Not all models have a thermal switch on the compressor so you just have to look and see. If it does you'll have a 3 wire plug at the compressor. If there is only one wire at the compressor there is no thermal switch.
The AC cut relay is normally closed so should show continuity at all times. This relay is controlled by the evaporator thermal switch, and will only open if the evaporator core gets too cold.

The pressure switch controls the coil side of the main AC relay. Power flows from the mode control panel, to the pressure switch, then to the AC relay, then through the thermal switch on the evaporator, then to ground through the fan switch in the mode control panel.

You can easily check for 12v at the pressure switch when the control panel is set to an AC position.

If you have the thermal switch on the compressor you can check for 12v there. Also check for continuity through the switch.

#13 provin1327

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Posted 09 May 2014 - 11:40 AM

I believe when I checked for voltage at that 3 wire plug on the input side I didnt have voltage but I will have to check again this weekend. Currently at work and cant test. I will try to update on Sunday, thank you so much for the information so far, wiring is not my strong suit

Edited by provin1327, 09 May 2014 - 12:51 PM.


#14 provin1327

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Posted 09 May 2014 - 04:48 PM

So I recharged the system and found a small leak on the low pressure side at the o ring. Now the clutch was engaging but was still blowing hot. I poked under the passenger footwell and pulled the cable that is on the flap, it was blowing over the heater core the whole time. New problem is finding out how to fix that because the heat/ac temp blend knob on the dash doesn't do anything. Is there a fuse or a relay for the motor that controls this?

Edited by provin1327, 09 May 2014 - 06:50 PM.





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