P38A Fault code

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Just to make sure I understand correctly, when you say you put the jumper back in to get the clutch to engage are you inserting the jumper in the fuse box where the relay plugs in? If that is the case you have power at the relay but it is not closing its contacts because it is not getting voltage to its coil. There are 3 most likely possibilities:
-low on gas
-connector behind kick panel corroded
-trinary switch is bad
The trinary switch will disconnect power to the clutch if it thinks gas pressure is too low or two high. It is the switch on the receiver dryer behind the bumper. It points forward. The other switch in that area is part of the fan control system and does not affect the clutch.
According to the service manual if the outdoor temp is in the 20-24C range the vents should give air at 4-10C and pressures should be 18-28psi for low pressure side and 213-299psi on the high side.

If you are getting refrigerant gauges you can check the pressure
 
Gord Wedman said:
Just to make sure I understand correctly, when you say you put the jumper back in to get the clutch to engage are you inserting the jumper in the fuse box where the relay plugs in? If that is the case you have power at the relay but it is not closing its contacts because it is not getting voltage to its coil. There are 3 most likely possibilities:
-low on gas
-connector behind kick panel corroded
-trinary switch is bad
The trinary switch will disconnect power to the clutch if it thinks gas pressure is too low or two high. It is the switch on the receiver dryer behind the bumper. It points forward. The other switch in that area is part of the fan control system and does not affect the clutch.
According to the service manual if the outdoor temp is in the 20-24C range the vents should give air at 4-10C and pressures should be 18-28psi for low pressure side and 213-299psi on the high side.

If you are getting refrigerant gauges you can check the pressure
Click to expand...
Very helpful, you'll have to check in Rave wiring diagram, I can't remember if yours is petrol or diesel.on my MY97 diesel but do you have continuity between the trinary switch and the compressor? From memory the switch relies on a grant from the hevac,wether this goes to the becm which then sends power to the switch I'm not sure. Good luck Pete.
 
I briefly read RAVE and I think the process goes like this:
You ask for cooling on the Hevac and it asks the ECU if that is OK. ECU checks engine temp to be sure engine is not overheating and then sends an OK to BeCM. BeCM sends power to relay which then closes and sends power to trinary switch which passes it to clutch if pressures are OK. There also a temperature check done on the evaporator to see if it is too cold/frozen.

You can there are lots of other places where a problem could arise so I just listed the 3 that seem most common. Defective Hevac controller might be a fourth.
 
Gord Wedman said:
I briefly read RAVE and I think the process goes like this:
You ask for cooling on the Hevac and it asks the ECU if that is OK. ECU checks engine temp to be sure engine is not overheating and then sends an OK to BeCM. BeCM sends power to relay which then closes and sends power to trinary switch which passes it to clutch if pressures are OK. There also a temperature check done on the evaporator to see if it is too cold/frozen.

You can there are lots of other places where a problem could arise so I just listed the 3 that seem most common. Defective Hevac controller might be a fourth.
Click to expand...
I'm sure JLR could have made it more complicated if they really tried.:rolleyes::D:D
 
Yes, it is fairly complicated but I doubt much more than any other climate control system. Everything can be fairly easily replaced or fixed except for the Hevac control unit, ECU and BeCM. If the latter two are bad you have a lot more problems. Once all the good Hevac controllers are gone, and no one is fixing bad ones, we will be in a pickle.
 
Not had a chance to do much this wkend drained out all the coolant that was in it the pressures were lower than you had posted I’m going to still check for leaks nxt weekend then put in the stop leak stuff re fill and go from there sorry can’t post more but been a hectic wkend
 
Gord Wedman said:
Yes, it is fairly complicated but I doubt much more than any other climate control system. Everything can be fairly easily replaced or fixed except for the Hevac control unit, ECU and BeCM. If the latter two are bad you have a lot more problems. Once all the good Hevac controllers are gone, and no one is fixing bad ones, we will be in a pickle.
Click to expand...
Just like the wiring for the heated front screen.:rolleyes::D
 
pete12345 said:
Not had a chance to do much this wkend drained out all the coolant that was in it the pressures were lower than you had posted I’m going to still check for leaks nxt weekend then put in the stop leak stuff re fill and go from there sorry can’t post more but been a hectic wkend
Click to expand...
I've used the stop leak stuff in mine and it's worked a treat Oh my god what have I just said:eek::eek::D
 
Checked the pressure it’s holdin pressure after a vacuum put a leak test through it nothing seen got new switches and dryer will replace when get the chance can anybody tell me what’s inside the new dryer I started to remove one of the plastic caps and heard a bit of hissing ???? bit ov a worry I won’t be on it this wkend had 2 jab feel like ,,,,,,,, cheers for advice
 
The drier has some type of dessicant intended to remove water from the system. Was possibly vacuum packed so the hissing was air entering. You shouldn't really open this until just before adding however if you put vacuum the system for something like 4 hours you should remove any moisture that has been absorbed.
 
Slow process nothing done yet you couldn’t ,,,,,,,,,, make it up I checked for leaks with the dye last wkend nothing so thought good then came indoors with torch on it was the wrong one so had to order a uv one got home from work Friday checked it last night bloody dye everywhere so cleaning it off tonight and re try tomorrow I think most of the dye is old stuff no time to work on the old girl today had to go to Bournemouth so daughter could see her new university and accommodations for this year
 
Evening all re gassed new tri switch and dryer fitted still no joy with the clutch cutting in tho but cold air when jump the relay will plug the nanocom in tomorrow oh and connector behind footwell soldered
 
If jumping the relay gets you cold air then the relay is not getting power. Since you have replaced the trinary switch and did away with the connector it seems to me that the only remaining culprits are the HEVAC control head, faulty wiring or relay.
 
Just run live data on the air con and all it says in the values is aircon grant no will keep looking in different menus see I’ve I can find a live feed or anything
 
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