Overheating Series 3 ?
Veteran Member
Joined: Mar 2008
Posts: 25,528
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From: Pacific Northwest USA
The bend-a-wrench idea sounds plausible. Wish I could give some useful advice but the last time I changed one was surely over 20 years ago. All I remember it that it wasn't pleasant. 
Cheers
DD
Cheers
DD
Veteran Member
Joined: Mar 2007
Posts: 9,137
Likes: 2,659
From: Florida
yes that's it.
I remember using a very long 3/8" Breaker bar with a 1-1/8" crows foot open wrench to loosen the thermal sensor from above, then removed it by hand and quickly inserted the new one. ( I borrowed the tools from my mechanic).
**this was done when the engine and coolant were cold, didn't want to burn my hands.
Coolant gushed out as expected but I had a pan ready to collect it.
I recommend buying the replacement from SNG Barratt, not a cheap copy from elsewhere. You only want to do this job once.
I remember using a very long 3/8" Breaker bar with a 1-1/8" crows foot open wrench to loosen the thermal sensor from above, then removed it by hand and quickly inserted the new one. ( I borrowed the tools from my mechanic).
**this was done when the engine and coolant were cold, didn't want to burn my hands.
Coolant gushed out as expected but I had a pan ready to collect it.
I recommend buying the replacement from SNG Barratt, not a cheap copy from elsewhere. You only want to do this job once.
Junior Member
Joined: Sep 2024
Posts: 1
Likes: 1
I'll only consider this if I can't change the sensor -- but I think I found the axillary fan mod mentioned above. My solution for accessing the sensor: use a torch to bend a wrench at an angle that will reach it. According to the information I found, you can use either a 29mm or 1-1/8 wrench for the deed.
"Mike and the List,
Hi List, Here is a procedure for adding the diode so the aux fan comes on
with the compressor. This mod will cost less than $10.00. It will lower
high side pressures on cars with R-134a by 30-50 lbs when the car is not
moving, greatly enhancing cooling when stuck in traffic, and keeping the
system from blowing the hoses and seals out. It is even beneficial to R-12
and R-406 cars. The parts and supplies need are readily available at any
Radio Shack or any electronics parts house.
Tools Needed: Soldering iron, crimping tool, wire strippers, pliers
Supplies needed: Solder (rosin core), 2 feet of insulated wire (recommend 18
gauge), diode (1N4001, 1N4002, 1N4003) or equivalent, heat shrink tubing
(assorted sizes and lengths), some type of disconnect crimp-on connectors,
male and female (spade type will do, bullet type better, aviation knife type
best but hard to find, a couple of 3-way splicing connectors if you don't
want to cut any wires).
Procedure:
1: Disconnect the negative battery cable. You will be working with/near
wires that may have power applied even with the ignition off
2: First of all, locate the wires you will be splicing in to. On the A/C
compressor side, it is the 12 volt wire going directly to the compressor
clutch. On my car this is a green wire going directly to the clutch plug.
This is one of the two you will be tapping into. Do NOT use the black wire as
this is ground (earth). Next, remove the plug going to the aux fan relay
(normally a red Lucas relay or maybe a black Bosch one like mine). It's on
the left side near the top of the radiator support frame on the engine
compartment side. Next locate the Green wire with a white stripe going to
this relay. It is the one farthest to the right when plugged in and mounted
normally. This is the other wire you will be tapping into.
2: Next, make up the diode harness. Cut the length of spare wire in half,
strip one end of each wire and solder one piece to each of the two leads
coming out of the diode. (If you don't have soldering skills or equipment
you can use red butt type crimp connectors here, just make sure they are
tight). Identify the "cathode" end of the diode. It is the end with the
marker band around it. Tie a knot or otherwise mark the wire attached to the
cathode end as not to get them confused later. Then take a piece of heat
shrink tubing just big enough around to slip over the diode and long enough
to cover all bare wire and heat it to form insulation around the diode.
Repeat this process as to end up with two layers covering the diode and
exposed wires.
3: Connect It. Using the three way splicing connectors or other means that
you like, connect the end you marked or tied the knot in (cathode) to the
green/white wire you located previously which goes to the connector to the
fan relay. I like to use disconnect type connectors somewhere in line here so
this can be disconnected for any troubleshooting that might be needed in the
future. Next, connect the other end of the wire attached to the non-banded
(anode) end of the diode to the green wire previously found going to the
compressor clutch plug, making sure the wire is routed so that it will
interfere with nothing else.
4: Test It: Reconnect the negative battery cable. Turn the Climate control
off. Start the car. Verify the Aux fan is not running. Turn on the A/C.
Verify the aux fan is running. Turn A/C off with car running. Verify the
Aux fan is not running.
Notes:
1. No additional fusing is needed as this mod simply uses the compressor
clutch power to activate the relay that powers the aux fan.
2. Some Jaguar schematics show a diode in exactly this position for this
function, although some show it opposite polarity than is needed, (a misprint
I'm sure). Some later prints show it correctly.
3. Apparently, some cars come like this from the factory, mainly 12 cyl
versions.
4. This is a first draft of this procedure and I've made every effort for it
to be complete and correct. I certainly welcome any corrections,
clarifications, or better ideas.
Steve Randall
85XJ6 with COOL A/C"
"Mike and the List,
Hi List, Here is a procedure for adding the diode so the aux fan comes on
with the compressor. This mod will cost less than $10.00. It will lower
high side pressures on cars with R-134a by 30-50 lbs when the car is not
moving, greatly enhancing cooling when stuck in traffic, and keeping the
system from blowing the hoses and seals out. It is even beneficial to R-12
and R-406 cars. The parts and supplies need are readily available at any
Radio Shack or any electronics parts house.
Spoiler
Supplies needed: Solder (rosin core), 2 feet of insulated wire (recommend 18
gauge), diode (1N4001, 1N4002, 1N4003) or equivalent, heat shrink tubing
(assorted sizes and lengths), some type of disconnect crimp-on connectors,
male and female (spade type will do, bullet type better, aviation knife type
best but hard to find, a couple of 3-way splicing connectors if you don't
want to cut any wires).
Procedure:
1: Disconnect the negative battery cable. You will be working with/near
wires that may have power applied even with the ignition off
2: First of all, locate the wires you will be splicing in to. On the A/C
compressor side, it is the 12 volt wire going directly to the compressor
clutch. On my car this is a green wire going directly to the clutch plug.
This is one of the two you will be tapping into. Do NOT use the black wire as
this is ground (earth). Next, remove the plug going to the aux fan relay
(normally a red Lucas relay or maybe a black Bosch one like mine). It's on
the left side near the top of the radiator support frame on the engine
compartment side. Next locate the Green wire with a white stripe going to
this relay. It is the one farthest to the right when plugged in and mounted
normally. This is the other wire you will be tapping into.
2: Next, make up the diode harness. Cut the length of spare wire in half,
strip one end of each wire and solder one piece to each of the two leads
coming out of the diode. (If you don't have soldering skills or equipment
you can use red butt type crimp connectors here, just make sure they are
tight). Identify the "cathode" end of the diode. It is the end with the
marker band around it. Tie a knot or otherwise mark the wire attached to the
cathode end as not to get them confused later. Then take a piece of heat
shrink tubing just big enough around to slip over the diode and long enough
to cover all bare wire and heat it to form insulation around the diode.
Repeat this process as to end up with two layers covering the diode and
exposed wires.
3: Connect It. Using the three way splicing connectors or other means that
you like, connect the end you marked or tied the knot in (cathode) to the
green/white wire you located previously which goes to the connector to the
fan relay. I like to use disconnect type connectors somewhere in line here so
this can be disconnected for any troubleshooting that might be needed in the
future. Next, connect the other end of the wire attached to the non-banded
(anode) end of the diode to the green wire previously found going to the
compressor clutch plug, making sure the wire is routed so that it will
interfere with nothing else.
4: Test It: Reconnect the negative battery cable. Turn the Climate control
off. Start the car. Verify the Aux fan is not running. Turn on the A/C.
Verify the aux fan is running. Turn A/C off with car running. Verify the
Aux fan is not running.
Notes:
1. No additional fusing is needed as this mod simply uses the compressor
clutch power to activate the relay that powers the aux fan.
2. Some Jaguar schematics show a diode in exactly this position for this
function, although some show it opposite polarity than is needed, (a misprint
I'm sure). Some later prints show it correctly.
3. Apparently, some cars come like this from the factory, mainly 12 cyl
versions.
4. This is a first draft of this procedure and I've made every effort for it
to be complete and correct. I certainly welcome any corrections,
clarifications, or better ideas.
Steve Randall
85XJ6 with COOL A/C"
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