Let me run this past others........

[TonyN]

...in case I'm missing something stupid.

Problem...

KZN130 (Lindas' truck)

A/C compressor switches off when in any gear, works fine in P or N.

So far I've changed/swapped/checked...

Recharged A/C Gas
Expansion valve
Main ECU
A/C ECU
Coolant Temp sensor
Compressor clutch
A/C relays and fuses behind dash.

Now its starting to drive me nuts. Any ideas?

I think I'm gonna unplug the gearbox so it has to shift manually, and try that next, then try it with the shift selector plug unplugged and see what happens.

[That Ruddy Squirrel]

Any loose wires ?

dodgy earth ?

[BUSHWHACKER]

Idle speed too low.

[gwh200]

...in case I'm missing something stupid.

Problem...

KZN130 (Lindas' truck)

A/C compressor switches off when in any gear, works fine in P or N.

So far I've changed/swapped/checked...

Recharged A/C Gas
Expansion valve
Main ECU
A/C ECU
Coolant Temp sensor
Compressor clutch
A/C relays and fuses behind dash.

Now its starting to drive me nuts. Any ideas?

I think I'm gonna unplug the gearbox so it has to shift manually, and try that next, then try it with the shift selector plug unplugged and see what happens.

mine used to do the complete opposite,it would stop when in neutral.when woodzie ripped out the aircon rads,it left me with a permanent drain through the starter relay,which was connected to the earth strap that ran from the evap fans to the chassis.i mention this as it was possible to turn the starter over when the engine was running,and the inhibit was not earthed,and was supposed to be,and as far as i can see was throught the earth strap down to the fans.if the earth at the fans is less than perfect,(and mine was a major connection) it caused me loads of issues,one being the aircon going off in p and n

[Vagrant No2]

It does sound like a live being used as an earth somewhere causing the compressor to drop out of engagement. As suggested a high resistance in a connection or earth return could be causing this and causing the live to switch to earth when gear selected

Edit due to spelling and to much red wine , hic !!

[BioHazard]

mine used to do the complete opposite,it would stop when in neutral.when woodzie ripped out the aircon rads,it left me with a permanent drain through the starter relay,which was connected to the earth strap that ran from the evap fans to the chassis.i mention this as it was possible to turn the starter over when the engine was running,and the inhibit was not earthed,and was supposed to be,and as far as i can see was throught the earth strap down to the fans.if the earth at the fans is less than perfect,(and mine was a major connection) it caused me loads of issues,one being the aircon going off in p and n

That was only due to it being altered from standard

[gwh200]

That was only due to it being altered from standard

oh not trying to infer anything at all ian.it had stopped working prior to the lift and it was always the plan to take it out anyway.it was just the "hidden" connections that were wired to it,notably the weird non running in n or p,and the battery drian with the earth strap gone. was on no account anything you,i or stein did,it was a failure already built into it

[BUSHWHACKER]

oh not trying to infer anything at all ian.it had stopped working prior to the lift and it was always the plan to take it out anyway.it was just the "hidden" connections that were wired to it,notably the weird non running in n or p,and the battery drian with the earth strap gone. was on no account anything you,i or stein did,it was a failure already built into it

Good ole RAC.


The roads were empty on the way home anyway.

[gwh200]

Good ole RAC.


The roads were empty on the way home anyway.

good god i nearly forgot !!!!

vince ,didnt you get home in about 50 minutes or something equally as fast !!

(but not as fast as an rac man that turns up 10 minutes after you call them !!)

[BUSHWHACKER]

good god i nearly forgot !!!!

vince ,didnt you get home in about 50 minutes or something equally as fast !!

(but not as fast as an rac man that turns up 10 minutes after you call them !!)

Yep, at one point I nearly met myself coming back!!

[gwh200]

a warp factor 9 slingshot round the sun

(for our purposes the sun is what we commonly refer to as the m4)
tony,
is there not a rotation sensor in the compressor that stops the compressor being spun out of control,when the engine is being revved.?
when you are in neutral and or park,with the a/c on does the engine rpm inrease up and down as the a/c comes on and off,if not the sensor in the compressor could be gubbed

[TonyN]

Any loose wires ?

dodgy earth ?

Not that I've found

Idle speed too low.

Nope, or it would switch back in when you rev it right?

It does sound like a live being used as an earth somewhere cuasing the compressor to drop out of engagement. As suggested a high resistance in a connection or earth return could be causing this.

But why only in gears, never in N or P. I can see Gra's problem, as he said it caused lot of other problems, related to the starter circuit and its duff earth. Nothing else is wrong with our truck.

Something switches off the A/C, as soon as you select a gear, I need to find out what turns off the A/C via the ECU, like the temp sensor when the motor gets hot or the throttle position sensor at full throttle and see if one of these is faulty and telling the ECU to turn it off. But we have no fault codes either.

I have had the motor out since this problem occured, so would have found any obvious broken wires.

If it is a duff neg somewhere else, finding out what circuit is switching on in any gear but not in N or P but not logging it on the ECU fault is gonna be a bugger!!

is there not a rotation sensor in the compressor that stops the compressor being spun out of control,when the engine is being revved.?
when you are in neutral and or park,with the a/c on does the engine rpm inrease up and down as the a/c comes on and off,if not the sensor in the compressor could be gubbed

When in N and P everything works sweet, from idle to the rev limiter. And in N or P the revs drop and rise as it switches in and out when left running.

There nothing in the compressor to stop in reving, there might be a rpm cut off via the engine speed sensor, but these arn't showing faults, just like the TPS and the temp sensor.

I might just have to wire up the compressor power wire via a switch, so its completely manual. But its bugging me that something related to cutting the A/C off could also be affecting the fuel pump and power, as the ECU turns the A/C off when it thinks your overheating or under full throttle, so the ECU might be restricing our power as well due to something playing up and telling lies.

[gwh200]

making it run independently of the rest of the electrical system,seems the way forward.at least if its running independently it cant interfere with other circuits,and cant send the ecu spurious alarms

[TonyN]

making it run independently of the rest of the electrical system,seems the way forward.at least if its running independently it cant interfere with other circuits,and cant send the ecu spurious alarms

Yeah, but I'm worried something else is telling it to shut off, thinking the engine is hot/cold, etc....and this will effect how it runs as well.

[Koi]

Might help ???????????????

http://www.toyotasurf.asn.au/techsite/aircon.htm