EAS Pressure switch

Sorry for another EAS question but I think I am going mad.

Maybe I am wrong, but I am sure there was a section in the "how to" from Wammers that advised on confirming a faulty pressure switch, or was it a dream? Not that I dream of LandyZone.

My problem is that the compressor will not run. If I jump 3 and 5 on relay 20 it runs. If I use the EAS unlock software it runs. No other time.

I have checked suction on the inlet (yes seems ok) and pressure on the outlet (not great but certainly pressure there).

I checked the thermal switch and have continuity between orange and black.

When I manually force the compressor to run, all is ok. After 30 mins or so or driving the pressure unsurprisingly drops and I get an EAS fault, 35MPH message. Stop, reset on the laptop, manually force the compressor, all ok again.

I am sure my initial problem is the pressure switch. How to fault find it?
Cannot find the answer on RangeRovers.net either :-(

Cheers in advance.

JamesBB said:

Sorry for another EAS question but I think I am going mad.

Maybe I am wrong, but I am sure there was a section in the "how to" from Wammers that advised on confirming a faulty pressure switch, or was it a dream? Not that I dream of LandyZone.

My problem is that the compressor will not run. If I jump 3 and 5 on relay 20 it runs. If I use the EAS unlock software it runs. No other time.

I have checked suction on the inlet (yes seems ok) and pressure on the outlet (not great but certainly pressure there).

I checked the thermal switch and have continuity between orange and black.

When I manually force the compressor to run, all is ok. After 30 mins or so or driving the pressure unsurprisingly drops and I get an EAS fault, 35MPH message. Stop, reset on the laptop, manually force the compressor, all ok again.

I am sure my initial problem is the pressure switch. How to fault find it?
Cannot find the answer on RangeRovers.net either :-(

Cheers in advance.

Click to expand...

Pressure switch should be open circuit below 120 psi and closed circuit at or above 140 psi. + or - 7 psi at either end. Try cleaning the pins in the plug the pressure switch wires go into. Two red wires. Check for good earth at point between EAS box and wing.

wammers said:

Pressure switch should be open circuit below 120 psi and closed circuit at or above 140 psi. + or - 7 psi at either end. Try cleaning the pins in the plug the pressure switch wires go into. Two red wires. Check for good earth at point between EAS box and wing.

Click to expand...

Cheers, will try and check over the weekend then.

I've had continuity on the thermal switch and it has still been knackered. Can be tricky little devils. Only a fiver to replace. It's at the end of the compressor motor.

The pressure switch is usually OK. Hidden on the bottom of the valve block.

J

Grrrrrr said:

I've had continuity on the thermal switch and it has still been knackered. Can be tricky little devils. Only a fiver to replace. It's at the end of the compressor motor.

The pressure switch is usually OK. Hidden on the bottom of the valve block.

J

Click to expand...

Thanks for that.

Tested again this morning.
Thermal continuity is still ok - as it should be when cold, I have a spare thermal switch - got one a month or so ago as I suspected it originally so I may as well fit it simply to eliminate it anyway.

Pressure switch is totally open circuit, so I guess this also implies the pressure is low and the system should start the compressor as both thermal and pressure signals are go. Hmmm.

Will change that thermal switch and see what happens.
Failing that, I guess it could be a break in the wiring from the ECU? Need to find the ECU pinouts and check continuity to the EAS box. Although, I suspect that as the software starts it the wiring may be ok........
What are your thoughts guys?

Cheers

I still think its your compressor faulty, they can become intermittent, though I am no expert.

Check for a burning smell in the underbonnet fuse box and look at the pins on the relay for blueing and signs of heating.

Checked fusebox, all looks and smells ok. Contacts on relay are clean and shiny.

Compressor comes on with relay jumpered, also with EAS software, so the ECU is triggering the relay.

If the compressor is faulty, why would it come on manually at all? Comes back to the thermal switch needing to be eliminated.

Unless I can find another P38 in the area who has a working compressor that I borrow for a few mins to eliminate the entire unit.

JamesBB said:

Checked fusebox, all looks and smells ok. Contacts on relay are clean and shiny.

Compressor comes on with relay jumpered, also with EAS software, so the ECU is triggering the relay.

If the compressor is faulty, why would it come on manually at all? Comes back to the thermal switch needing to be eliminated.

Unless I can find another P38 in the area who has a working compressor that I borrow for a few mins to eliminate the entire unit.

Click to expand...

You are right, thermal switch or connections, there has been at least one incident of the thermal switch wire being broken where it is crimped in the connector.

Datatek said:

You are right, thermal switch or connections, there has been at least one incident of the thermal switch wire being broken where it is crimped in the connector.

Click to expand...

Definitely agree, I have had the same problem, though my thermal trip was crimped ok at the plug end, worth checking on yours

Thanks for your help again guys.

Going to spend a bit of time on it over the next week and will give feedback once I have checked the wiring and connections plus fit this thermal switch I have had kicking around a month..

Update, well it has been quite a while and I have been up to lots of other things like the headlining and non car related stuff like building a base board for my 9 year old son's (and mine) model railway.

Basically I changed the thermal switch, during the process I found the orange wire was so loose it actually came away from the connection post on the PCB without any effort. I re-soldered that back in place.

I decided to replace the switch anyway and I cleaned up the commutator and the brushes too. I used the same method on the commutator as I do on old Hornby/Triang motors and it worked a treat.

The compressor essentially is now working all on its own as per normal, I think. I certainly came on with the engine, I left it for 5 mins with the door open and it began to lift once I closed the door. Did not run it long enough to charge the tank fully, will do that tomorrow and run through Wammers "How To" again as I suspect it may need new O rings, the piston's Teflon ring is ok, looks as new.

While researching on the compressor rebuild I found a site that I ended up implementing the fix on mine, although slightly different. EAS Compressor End Bushing Repair

This guy uses a skate board bearing size (608ZZ) in place of that naff design piece in the OEM. These bearing are available on eBay and are cheap enough to give a try, nothing to lose. The end result is the compressor runs really smoothly, and as he says I am not sure how long it will last but fingers crossed....... I found my motor shaft was a very snug fitted into the bearing.

Might post some pics in a new thread later.

Cheers