DB7 i6 Air Con Fuse Location?
Discussion
Can anyone help?
I'm trying to find the fuse locations for the air con on my 1995 DB7i6.
Here's the story...
Bought the car knowing there was an air con issue. Had the air con compressor changed as clutch in it had gone kaput. System recharged, no leaks, all good with one exception, the air con won't switch on as it should. If the control system is bypassed by just energising the clutch on the compressor with +12v everything works dandy. As the clutch is the last part of the electrical chain I work my way back to the relay, which took an age to find due to wrong info in the manual. Relay is a tad burned. Swopped it for another... nothing. Checked terminals for voltage reading in the socket where the relay resides. I have +14v on one side of the relay coil and nothing on the other side. If I check for continuity between the dead side and chassis there is also nothing. I'm guessing (hoping) that this side may be fused (and that it has blown) and the +14v reading on the live side is the supply being sent from the aircon ecu.
Can anyone shed some light?
Quick update...
I've now found the ac relay fuse in the drivers side fuse box (no.4 5amp) and was praying for it to be blown, alas it is in tact and checked out fine. Now I'm really scratching my head, I'm technically minded but no auto electrician or air con expert for that matter. Seems to me that as there is +14v at the relay terminal something else is interrupting the circuit path to earth. I did read there is something called a trinary switch that can interrupt the supply if there is a fault.
In the manual it says the following about this...
"Trinary Switch
The high side low pressure switch (HSLP) is connected in the earth-ground return lead of the compressor clutch coil. The switch is a function of the trinary switch and monitors the pressure on the high side of the refrigeration system. If the pressure drops below 25psi (+5psi) the contacts open to de-energise the clutch coil and disengage the clutch. Low pressure occurs when there is a fault in the system, and the HSLP switch contacts remain open until the fault has been rectified."
As the system was depressurised when work was carried out my theory is this switch must be stuck as the system pressure has been checked after re-gassing and is all good.
So my new question is...
Does anyone know where on the car this switch is located? I can't find it in the manual.
Please help...
I'm trying to find the fuse locations for the air con on my 1995 DB7i6.
Here's the story...
Bought the car knowing there was an air con issue. Had the air con compressor changed as clutch in it had gone kaput. System recharged, no leaks, all good with one exception, the air con won't switch on as it should. If the control system is bypassed by just energising the clutch on the compressor with +12v everything works dandy. As the clutch is the last part of the electrical chain I work my way back to the relay, which took an age to find due to wrong info in the manual. Relay is a tad burned. Swopped it for another... nothing. Checked terminals for voltage reading in the socket where the relay resides. I have +14v on one side of the relay coil and nothing on the other side. If I check for continuity between the dead side and chassis there is also nothing. I'm guessing (hoping) that this side may be fused (and that it has blown) and the +14v reading on the live side is the supply being sent from the aircon ecu.
Can anyone shed some light?
Quick update...
I've now found the ac relay fuse in the drivers side fuse box (no.4 5amp) and was praying for it to be blown, alas it is in tact and checked out fine. Now I'm really scratching my head, I'm technically minded but no auto electrician or air con expert for that matter. Seems to me that as there is +14v at the relay terminal something else is interrupting the circuit path to earth. I did read there is something called a trinary switch that can interrupt the supply if there is a fault.
In the manual it says the following about this...
"Trinary Switch
The high side low pressure switch (HSLP) is connected in the earth-ground return lead of the compressor clutch coil. The switch is a function of the trinary switch and monitors the pressure on the high side of the refrigeration system. If the pressure drops below 25psi (+5psi) the contacts open to de-energise the clutch coil and disengage the clutch. Low pressure occurs when there is a fault in the system, and the HSLP switch contacts remain open until the fault has been rectified."
As the system was depressurised when work was carried out my theory is this switch must be stuck as the system pressure has been checked after re-gassing and is all good.
So my new question is...
Does anyone know where on the car this switch is located? I can't find it in the manual.
Please help...
Edited by ashriggs on Saturday 9th October 20:57
Hi Ashley sorry missed your original post, from the description it most likely the trinary Switch it is located in one of the two air con pipes running down the drivers side of the engine bay assuming it is a right hand drive car it is in the pipe than runs from receiver drier fitted on top of the radiator, it is round in shape and screws into the pipe, and has about a six inch of wire attached, de pressurising of the aircon system will be required for removal, as the switch closes on low pressure or high pressure tgo cut power to the air con compressor unless you can simulate these conditions then it will be difficult to test, this can be done by using the air con charging equipment to lower pressure and monitor the switch and then take the pressure above normal and test again, On removal it has a jaguar part number stamped on it
For the benefit of anyone else having the same problem and who dares to open the bonnet of their car here is what I have found...
If you disconnect the multiplug from the trinary switch, on the car loom side of the cable, with the connections inside pointing towards you with the side of the plug that normally faces the rear of the alternator still in that position, the top and bottom left ones are the fan connections, while the top and bottom rights ones are the negative-earth connections for the compressor relay coil. Ignition was on when testing this.
On the corresponding connections of the trinary switch side of the cable, assuming the pressure is correct, you should have a dead short between the compressor relay pins and open circuit on the fan (unless the pressure rises then they should be a dead short thus engaging the fan and an open circuit on the compressor connections which disengages the compressor).
Hope that helps someone.
If you disconnect the multiplug from the trinary switch, on the car loom side of the cable, with the connections inside pointing towards you with the side of the plug that normally faces the rear of the alternator still in that position, the top and bottom left ones are the fan connections, while the top and bottom rights ones are the negative-earth connections for the compressor relay coil. Ignition was on when testing this.
On the corresponding connections of the trinary switch side of the cable, assuming the pressure is correct, you should have a dead short between the compressor relay pins and open circuit on the fan (unless the pressure rises then they should be a dead short thus engaging the fan and an open circuit on the compressor connections which disengages the compressor).
Hope that helps someone.
Edited by ashriggs on Tuesday 12th October 15:31
Gassing Station | Aston Martin | Top of Page | What's New | My Stuff