Aircon Gemlins - No Pwr To Compressor

[jaik]

Gday,

I went to get my Cefiro regassed today aswell as having a new Receiver Dryer installed and after getting all that done it turns out my Compressor isnt turning on. We ran power direct to the unit and it spins freely, so somewhere inbetween the signal is getting lost. I was wondering if anyone is a bit of a guru when it comes to the aircon systems (presume its the same as an R32) and what I can check myself to make sure its not something easy like a relay etc.

When I press the button on the Controls should that send a signal to the ECU, which then sends a signal to the Relay Box on the Drivers Side in the Engine Bay, and then to the Thermo fan and Compressor?

What could you advise me to check in between there so that I can hopefully get it up and running.

Thanks ppl!

JK

[jetpilot]

ok,

try this but i have an R33....

1. Check the Aircon relay in the engine bay near the postive termial in the black box. Should be a large blue relay.

2. Check under the dash...should be a red 10AMP fuse

goto the second row on the fuse panel,

it is the first fuse nearest to the firewall.

3. In the back of the boot...where ur battery is should be a blower fuse for the fan.....check also this fuse

I hope this helps u out

[jaik]

No good

Got me stuffed!

JK

[marcus32]

i had the same problem when i converted my AC it turned out to be a fuse not just the 10amp but there was a 15amp fuse also blown so just pull each one out and physically look and check each one under the drivers side. after replacing these two AC worked instantly fan kicked in and compressor too.

[jaik]

All my fuses are OK.

What happens when I press the AC button with the Fan on is I hear a little motor noise in the fan box area (presume its some sort of flap opening to allow the cool gases in), I dont hear the engine Idle higher (No AAC Valve activating?) and the clutch on the compressor wont engage. Ive swapped the Aircon Relays and that made no difference. So Im not sure if there is a signal getting from my aircon button to the ECU to turn the rest of the system on?

What do you guys reckon?

JK

[jaik]

I found this - so perhaps I need to check if there is any sort of voltages coming IN from pin 46 - AC Switch and going OUT to pin 9 - AC Relay.

Also would pin 6 be the front termo fan?

Anyone know if Im right on that assumption?

Ecu pinout: rb20det eccs control unit pin layout.

1 Ign signal (power transistor) Cyl #1

2 Ign signal (power transistor) Cyl #5

3 Ign signal (power transistor) Cyl #3

5 engine. A/T control input signal (bt1)

6 Sub electrical fan relay (engine temp switch)

7 Tacometeter speed signal

9 AC relay (AC cut signal)

10 Ground (ign signal system)

11 Ign signal (power transistor) Cyl #6

12 Ign signal (power transistor) Cyl #2

13 Ign signal (power transistor) Cyl #4

14 engine. a/t control input sigal (bt2)

15 engine. a/t control input sigal (bt3)

16 ECCS relay

18 fuel pump relay

19 Power steering switch

20 Ground (ignition signal system)

21(RX) Receive (control unit data reception)

22 (TX) Transmit (data sent from control unit)

23 Detonation sensor 1 (cyl 1-3)

24 Detonation sensor 2 (cyl 4-6)

26 Air flow meter ground

27 Air flow meter intake air quantity signal

28 Engine temp sensor

29 Exhaust gas sensor

30 Sensor ground (throttle sen, ENG temp)

31 clock (synchronization signal)

32 Monitor and check lamp (red)

38 Throttle opening output

41 Crank angle sensor (120degree signal)

42 Crank angle sensor (1 degree signal)

43 Ignition switch START signal

44 Neutral switch

45 Ignition switch (IGN)

46 AC switch

47 (CHK) Check (diagnosis activation)

48 Throttle sensor power supply

49 Control unit power supply

50 Ground (control unit)

51 Crank angle sensor (120 degree signal)

52 Crank angle sensor (1 degree signal)

53 Vehicle speed sensor

54 Throttle valve switch (idle connection pt)

56 Throttle sensor output signal

57 Throttle valve switch power supply

58 Battery power supply

59 Control unit power supply

60 Ground (control unit)

101 Injector #1

103 Injector #3

104 Fuel pump terminal voltage control output

105 Injector #2 107 Injector ground

108 Injector ground

109 Injector power supply

110 Injector #5

112 Injector #4

114 Injector #6

115 exhaust gas sensor heater ground

116 injector ground

[firecracker]

I am having same problem as JK

I re-gas it about a week ago from a mob in Auburn to convertion and he did leak test and changed two valve fitting but not changing dryer or oil. he said it's only optional and not to worry.

when he started A?C to test it. the compressor wasn't kicking in and keep blowing fuses like JK. relay was OK, fan was OK gas was there but some how drawing like 12 amp.

I can feel the cold air if I use 15 or 20amp fuse but blows short after..may be 30 sec.

I am seeing unique Auto sports at Castle hill this Tuesday and see how it goes...

Edited February 17, 2006 by firecracker

[jetpilot]

hey just a thought ...wat happens if the idiots put too much gas in the system

mayeb compressor works harder and blows fuses etc...

just a thought

[jaik]

I dont have the fuse problem... all my fuses are OK... I just have no power going to anything!

JK

[cowie165]

Same symptoms. Checked all fuses and when I press A/C there is no change in engine rpm.

Will report back if the auto elec finds anything.

What happened when you tested pin 9 and 46? Any change in voltage? Ceffys don't have a consult port do they?

[jaik]

I got this PM from marcus32. So I was thinking should I somehow bridge the two wires at the pressure switch connector to see if she fires up?

PM-

hey this is a link i used for my AC it contains a wiring daigrams for RB20 i hope these help you out.

Basically the ECU controls the AC via the AC relay as follows. The ECU monitors the state of the AC by pin 46 which gets earthed when the AC button is switch on. Once earthed the ECU then earths pin 9 (AC cut signal) which is the trigger for the AC relay and hence once earthed the relay switches on and provides power for the AC compressor.

The AC relay trigger wire first passes through the pressure switch before terminating at pin 9 so if the pressure switch is open (not enough pressure) the compressor won't switch on despite pin 9 being earthed.

If the AC relay is clicking when the AC button is pressed it would imply that the trigger side of the relay is working but if there is no voltage at the compressor you should look at the supply to the relay. The relay gets its supply from a 10A fuse which I believe is with the main fuse block inside the car (in the R32s at least).

If there is power up to pin 3 or 5 on the AC relay (should be pin 3) when the key is switched to ACC you should then check continuity between the other pin and the wire to the compressor.

http://www.skylinegts.co.uk/R32-Fuses.htm (english translation of fuse block)

This was all sent to me by BH_SLO32 very helpful guy indeed knows alot about the AC system so full credit to him for all this info. once again let me know if this was helpful.

[marcus32]

if u bridge the two wires u will here the AC relay clicking in the fuse box in the engine bay and if it fires up your pressure switch maybe faulty.

[jaik]

Yeah, so basically I shouldnt experience any sort of engine bay fire by bridging the wires I will give that a shot. Looking at this pic - http://www.sido-takushi.com/misc/r32ecu/aircon_manual.jpg

Im not too proficient with reading electrical diagrams so Im trying to piece together what stage my system is at once i press AirCon with the Fan Running (on say 1 or 2 or 3 speed) and hearing the aircon door (Diagram: Intake Door Actuator?) opening up to let cool air in.

JK

[BH_SLO32]

Jaik,

Isolating the problem is a process of elimination. I suggest you start by checking that power is available at the AC relay as follows.

With the key switched to the ACC position you should see approximately battery voltage at either pin 3 or 5. To identify which is pin 3 or 5 remove the relay and turn it upside down. The pins are printed near each terminal. This is the main power feed to the compressor.

Next check that approximately batt voltage is present at pin 1 or 2 when the key is turned to the IGN/ON position. This is the trigger wire feed for the relay and is earthed by pin 9 on the ECU. The power feed passes through the pressure switch before terminating at pin 9 on the ECU.

The pressure switch should be closed if adequate gas pressure is present otherwise it will open and interrupt the power feed to pin 9 on the ECU. With the key in the IGN position and the AC off, check that power is present at pin 9 (approx batt voltage). If no power is present check that power is present at the pressure switch. If the pressure switch is open power will only be present on one side of the switch implying that there is a low gas pressure or the switch is faulty.

If power is present at pin 9 when the AC is switched off, press the AC button and check the voltage at pin 9 drops to approximately 0 volts. This implies that the ECU is earthing pin 9 and activating the AC relay.

When the AC relay is switched by the ECU you should hear the AC relay clicking. Now if power is available to pin 3 or 5 as discussed earlier, triggering the relay will allow power to be present at the AC compressor IF there is no physical break in the wire feeding the compressor.

If you still don't have power present at the compressor do a continuity check of the wire between pin 3 or 5 of the AC relay and the compressor. If continuity is established and the resistance is low (less than 5 ohms) then further checks will be required which I will discuss separately if required. I don't think you will reach this point without finding a fault earlier in the fault finding process.

I haven't discussed the function of pin 46 yet as I suspect it not an issue with the ECU. If you reach a stumbling block along the way give me shout and I assist further.

Hope this helps

Cheers,

Ben

[jaik]

Well, the gremlins are definately lurking.

Last night I unplugged the Pressure switch on the Receiver Dryer and plugged in a manual switch and the system powered up ok! I plugged the Pressure Switch back in and the system powered up ok again. The plugs look pretty dirty inside so Im not sure if they are making good contact. I took the car to the aircon place today and had the system filled up with the right amount of gas. But it doesnt appear to turn on all the time, so Im still skeptical about the Pressure Switch still functioning correctly. Im tempted to bridge the wiring but Id prefer to have the proper failsafe mechanism in place as I dont exactly want the system to build up too much pressure and pop.

Ive since noticed my front thermo wont power on at all, and running 12v straight to it on the battery sees the fan turn about 1cm, but makes a big clicking noise, so I presume its stuffed. Ive since unplugged it permanantly.

Also I noticed today that my normal operating temp of 80c went up to 100 running the aircon without the thermo

On Another note, Under what conditions will the ECU turn off the airconditioning if using it in manual mode? Will it keep it on all the time or does it cut it at 100% Throttle?

Thanks!

JK

[BH_SLO32]

Jaik,

Sounds like you have found your problem - the pressure switch.

The pressure switch will not doubt be used to ensure the compressor operates only when adequate gas pressure is available and protects it if the system pressure is insufficient. I say this because it is a switch and therefore doesn't "monitor" pressure but rather requires a minimum pressure to close.

It sounds like thermo fan has some crook bearings and consequently is drawing a high current which no doubt has blown the fuse for the fan (in the engine bay for the R32's). I also suspect the thermo fan is driven purely by the temperature switch in the bottom of the radiator as per the R32 GTS-T and is independent of the AC system.

Pin 9 on the ECU is the AC cut signal which will switch off the compressor when you accelerate.

Cheers,

Edited February 22, 2006 by BH_SLO32

[jaik]

I suspect its the switch... although I presume I'd have to release all the gas to remove and replace it. However the switch would probably be "on" the whole time there is gas in there otherwise it would never let the system start if it only let power thru once pressure would build up (cause it would never get the chance to!) Since I know the system should be good I may bypass the switch for a little bit for testing purposes.

The fan may have blown a fuse but I dont know where it is... I will investigate it once I replace the fan if it doesnt power up. Looking at the diagram I linked above you are correct about it running per the water temp in the radiator. I hope that bit works or otherwise I may hook it up via a manual switch.

Also, just about the ECU cutting when you accelerate, it would use the compressor if you have a steady constant throttle right?

Oh and hows this for a joke now... sometimes my manual slider controls go funny... ie when the fan speed is set to off it actually runs in low... damn thing... I wish the Cefi had digital!

JK

[firecracker]

I am having same problem as JK

I re-gas it about a week ago from a mob in Auburn to convertion and he did leak test and changed two valve fitting but not changing dryer or oil. he said it's only optional and not to worry.

when he started A?C to test it. the compressor wasn't kicking in and keep blowing fuses like JK. relay was OK, fan was OK gas was there but some how drawing like 12 amp.

I can feel the cold air if I use 15 or 20amp fuse but blows short after..may be 30 sec.

I am seeing unique Auto sports at Castle hill this Tuesday and see how it goes...

Unique motor sports in Castle Hill just informed my compressor is dead!!

there was no 2nd hand part and he offered $790 to recondition my compressor plus fitting $150~200..

does anyone knows where to look for imported car parts? justjap don't have it and don't know where to look nomore.

Dame compressor!! guess I am gonna have hot air for the moment!!

[BH_SLO32]

[Also, just about the ECU cutting when you accelerate, it would use the compressor if you have a steady constant throttle right?

Yes, the ECU uses the TPS signal and engine revs in the logic to determine when to switch off the compressor.

Cheers

[jaik]

On a good note, the past 2 days the aircon has been running sweetly. The compressor sometimes is very audible from the cabin but generally not too bad. But I can really feel the compressor sucking soo much power off the motor, especially when I back of the throttle... it sounds like its slowing the motor down more than natural deceleration. Was thinking perhaps the compressor is actually quite hard to spin so thats why its pulling down the revs.

It idles ok though... generally about 700RPM with the aircon on... which is a bit low... but its steady.

JK