Thread: D1 - AC comp cluch not engaging?

If I remember correctly there is a high/low pressure switch in the system. If the gas is too low it will not engage the clutch, same if it's too high. Not sure how you would test if the pressure is too high or too low.
Hopefully a grown up will be along soon.

Cheers

Ivan

Simple , bridge the HPL switch, but dont do it for to long if the system isnt quite cooling properly.If the cooling is not good then you are probably low on gas .Check the terminals and connections for the Condensor fans and Temp gauge out on the thermostat housing.

I had a look in my reliable haynes manual.i quote from it so can you put on here if it different.my on road D1 is 93 with the sanden system and I just up dated 94 face lift and havnt worked in it.
the update has a denso system obviously made for japanese market.
not easily repaired-wiring nightmare--simple to make and requires time to pull apart.

the compressor relay set up is a good thing unlike some other systems.
the clutch runs battery power from the under bonet fuse box Fuse 3.these need no more than 10 amp fuse normally-a denso coil will pull 2-4 amps.

what is silly is they are conecting the rear system hot water control and heater fan blower relays system so that the rear fan and heater will turn on when the compressor is running.
to test bridge pin 30-power[brown/green--- pin 87[black/green].

pin 85 white/green is ignition power from an ignition relay to test

the problem is---Pin 86 is an earth trigger for the relay
I like this but because it usess low current flow.BUT just about any dirty conection will stop it.it has more than 4 mechanical contact switches that can give problems first test -pressure switch normally near dryeris a gas pressure switch it should have 2 wires. is a good place to start.unplug it

orange/brown wire.
use a normal test light conected to earth.with ignition on test light will earth the relay and turn on the clutch.24V light wont light up-an LED test light or multi meter will show a voltage reading even if the wiring is no allowing enough flow.

if it doesnt turn on the clutch diesels have a cut out system im assuming is a overheat water temp switch.if its got a electronic controledl diesel[with air flow meter type] then the ecu controls the clutch triger.

I often come across petrol vehicles of different types that because of poor joints in ecu or bad earth conections the a/c wouldnt work.
out of frustration the ecu was bypassed or other trigger like rpm cutouts and water temp switched fitted.

*Fuses are all good.
*AC comp Clutch relay is good.
*If I provide power to the relay block the cluch will engage and air is cold (gas levels OK). Loom from relay to comp OK.
*If I test for power at the relay block, I am not getting a switch signal (to switch the relay on).

* bypass the pressure switch makes no difference.

Really out of ideas, starting to think the head unit is stuffed. I'm worried about taking it to AC man who won't be able to follow the LR way of wiring it?

*If I provide power to the relay block the cluch will engage and air is cold (gas levels OK). Loom from relay to comp OK.
*If I test for power at the relay block, I am not getting a switch signal (to switch the relay on).

have you got 2 power terminals at the relay'then go to the next test.

I am not getting a switch signal ---Pin 86 is an earth trigger for the relay
-gas pressure switch has 2 wires. is a good place to start.unplug it and test for power on the orange/brown wire.
if it has power earth it with a test light and confirm clutch works.

If not its the engine compressor cut system [by pass it]or the front a/c thermostat more likely.

to test the head unit coct test light to battery power and check that the other pressure switch wire earths when the fan an a/c are turned on.

the head unit is at the end of the system and you could replace it with a simple relay or switch[operated by the fan circuit].

been out and looked at mine.fuses are near the battery-the clutch is 30 amp and thats enough for a small fireif the clutch melts.

pressure swith is part of the high pressure service valve on the liquid line.
not a good idea but engineers place it there to stop compressure cycling on high pressure on a hot day.
its rare that this position will ever get a high cutoutthe cltch plate rubber drive normally melt first.

the low side often triggers by a restriction in the dryer or condensor,normally just after the oil starved compressor has had a melt down.

IF you have a rear system dont put power to the rear fan to see if it works.

the power relay gounds the fan supply to stop feed back or radio noise.
I did this once to an late 80's toyotathat had harness issues and had to trace all the melted wires and replace the carpet burnt under the pedals.

are the wires connected to the thermostat switches in the right order, mine wasnt and the air con didnt work

Originally Posted by bigcarle

are the wires connected to the thermostat switches in the right order, mine wasnt and the air con didnt work

Hey there Carle, how's the camper electrics going? We've owned the car since 1996, and the AC worked until last week. It's our Fraser Is truck, and it lives in Hervey Bay - 370kms and still going strong.

Originally Posted by Davehoos

---Pin 86 is an earth trigger for the relay

This was the problem. Pin 85 has the + from the ign. 30 has the + from the fuse in the engine bay, but nothing was delivered to 86. Switch was outputting neg signal... switches under bonnet tested fine, clutch tested fine.

After completely dismantling the dash, I've found the loom that leads to the relay block has worn through from rubbing against a metal faming member right up under the steering column - guess which wire is broken?? I assume that being exposed to ground we would not have been able to turn the AC off for quite a while before it broke and separated.

All sorted, thanks all.