SPDrift Posted January 11, 2023 Report Share Posted January 11, 2023 Hi All, Having issues with getting my a/c to work in my s15 - manual climate control unit and the a/c button does not light up. SR20, Link G4X NS15X ECU I am a a/c noob so don't understand how the system works entirely but so far I have been able to do some diagnosing. 12V at climate control unit, 12V at aircon switch, 12V on pin 11 on ecu but no voltage at pin 41. Also, the thermo control amplifier does not have 12V also. I am not sure where to look next and was not sure if pin 41 should have 12v? Any help would be appreciated Quote Link to comment Share on other sites More sharing options...
Vaughan Posted January 11, 2023 Report Share Posted January 11, 2023 Does turning the switch on and off change DI 1 status in the ECU to Active and Inactive? Can you attach a copy of your basemap please Quote Link to comment Share on other sites More sharing options...
SPDrift Posted January 12, 2023 Author Report Share Posted January 12, 2023 No change in DI1 Ecu is password protected so I don’t think I have access to the map *edit - I just replaced the climate control unit and a/c switch is now lighting up, I assume my switch was faulty. No change in di1 Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 12, 2023 Report Share Posted January 12, 2023 Can you unplug the ecu and tell us the voltage on pin 41 in the loom with AC switch on and off (with ign switch on). Quote Link to comment Share on other sites More sharing options...
Vaughan Posted January 12, 2023 Report Share Posted January 12, 2023 If the DI isn't going Active then the ECU isn't being told to turn on the AC compressor, things that typically affect the signal from the button are the blower fan being off and the AC Pressure switch, ac pressure switches typically need to be short circuit across the two pins for the AC to work. Quote Link to comment Share on other sites More sharing options...
SPDrift Posted January 17, 2023 Author Report Share Posted January 17, 2023 On 1/12/2023 at 9:49 PM, Adamw said: Can you unplug the ecu and tell us the voltage on pin 41 in the loom with AC switch on and off (with ign switch on). I haven’t had a chance to unplug it yet and check out will do asap! On 1/13/2023 at 7:28 AM, Vaughan said: If the DI isn't going Active then the ECU isn't being told to turn on the AC compressor, things that typically affect the signal from the button are the blower fan being off and the AC Pressure switch, ac pressure switches typically need to be short circuit across the two pins for the AC to work. So I swapped the old climate unit for a another, the button is now lighting up. I do not have 12v at the pressure switch on the receiver drier, I also don’t have 12v at the thermo unit that is behind the glove box. I am stumped at what to do next Quote Link to comment Share on other sites More sharing options...
Vaughan Posted January 17, 2023 Report Share Posted January 17, 2023 Using a multimeter is there continuity across the ac pressure switch. Quote Link to comment Share on other sites More sharing options...
SPDrift Posted January 17, 2023 Author Report Share Posted January 17, 2023 7 hours ago, Vaughan said: Using a multimeter is there continuity across the ac pressure switch. No continuity on the pressure switch mate Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 17, 2023 Report Share Posted January 17, 2023 If the press switch is open circuit that would generally mean the pressure is too high or too low. Most commonly too low due to a leak. Quote Link to comment Share on other sites More sharing options...
SPDrift Posted January 17, 2023 Author Report Share Posted January 17, 2023 Not sure if this helps but I don’t have 12v at the pressure switch on the harness side could this be linked to the idle control valve, is that where it would get its power from? Quote Link to comment Share on other sites More sharing options...
Vaughan Posted January 17, 2023 Report Share Posted January 17, 2023 9 hours ago, SPDrift said: Not sure if this helps but I don’t have 12v at the pressure switch on the harness side could this be linked to the idle control valve, is that where it would get its power from? With the car not running short across the ac pressure plug with a piece of wire and then see if the pressing and unpressing the ac switch changes DI1 to Active and inactive, you will most likely need the blower/interior fan on when doing this. Quote Link to comment Share on other sites More sharing options...
SPDrift Posted January 18, 2023 Author Report Share Posted January 18, 2023 14 hours ago, Vaughan said: With the car not running short across the ac pressure plug with a piece of wire and then see if the pressing and unpressing the ac switch changes DI1 to Active and inactive, you will most likely need the blower/interior fan on when doing this. Just tried this and no luck.. no change on DI1 Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 18, 2023 Report Share Posted January 18, 2023 Below is the circuit diagram. For the symbols that reference another page: "A" is 12V from the fan switch, so the AC switch only has 12V when the fan switch is on. B goes the the AC control unit that controls the flaps etc. C is not relevant. So, 12V from the fan switch goes into pin 4 of the AC switch. Since you said your AC lamps is on I think we can assume this 12V is present. When the AC switch is on, 12V will go out of pin 3 of the AC switch up to pin 2 on the amp. If the amp has 12V on pin 1 (from fuse#15) and the thermistor is measuring an acceptable temperature (I assume this is measuring Evap temp or something) then you should have 12V coming out of amp pin 3 to the pressure switch. If the pressure switch is exposed to a acceptable pressure then it will be closed so the 12V will pass through to pin 41 on the ecu which is DI1/AC Request. Quote Link to comment Share on other sites More sharing options...
SPDrift Posted January 19, 2023 Author Report Share Posted January 19, 2023 14 hours ago, Adamw said: Below is the circuit diagram. For the symbols that reference another page: "A" is 12V from the fan switch, so the AC switch only has 12V when the fan switch is on. B goes the the AC control unit that controls the flaps etc. C is not relevant. So, 12V from the fan switch goes into pin 4 of the AC switch. Since you said your AC lamps is on I think we can assume this 12V is present. When the AC switch is on, 12V will go out of pin 3 of the AC switch up to pin 2 on the amp. If the amp has 12V on pin 1 (from fuse#15) and the thermistor is measuring an acceptable temperature (I assume this is measuring Evap temp or something) then you should have 12V coming out of amp pin 3 to the pressure switch. If the pressure switch is exposed to a acceptable pressure then it will be closed so the 12V will pass through to pin 41 on the ecu which is DI1/AC Request. Hi Adam, I had my auto elec/aircon man help me with this today - confirmed no gas in system but we shorted the pressure switch to bypass this. We ended up giving 12V direct to pin 41 and no change on DI1 - we did this to see if pin 11 is switching to low when pin 41 is getting 12V. We also bypassed the relay to confirm that the clutch would engage on compressor, also to eliminate wiring issues on that side of the relay. Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 19, 2023 Report Share Posted January 19, 2023 9 hours ago, SPDrift said: We ended up giving 12V direct to pin 41 and no change on DI1 Assuming DI 1 pull-up is off and active state is set to high you should definately see a change in status when connecting 12V to pin 41. Quote Link to comment Share on other sites More sharing options...
jdniss Posted January 20, 2023 Report Share Posted January 20, 2023 On 1/17/2023 at 1:18 PM, SPDrift said: So I swapped the old climate unit for a another, the button is now lighting up. Might be a stupid question - but I suspect some of these tests are done with the car running? The A/C climate control light illuminates with IGN on, but the A/C Clutch won't ever kick on unless the car is running - albeit after a short delay Quote Link to comment Share on other sites More sharing options...
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