Can you make the electric fan work if the A/C tank is empty?
CF Veteran
Joined: May 2008
Posts: 3,018
Likes: 23
Year: 1988
Model: Cherokee
Engine: AMC242
I'm sure it's possible, I just don't know how to do it (the idea for RENIX won't work - it uses a dedicated TFS in the radiator tank. OBD-II uses data from a single temperature sensor to drive temperature-related functions.)
Thread Starter
Seasoned Member
Joined: Jan 2009
Posts: 454
Likes: 0
From: Middle Tennessee
Year: 2001
Model: Cherokee
Engine: 4.0L I6
Wow i didn't exect so much good feedback 
Thanks, need to read through these now before I can comment.
And yes, R12 is what I meant to type =\
Didn't know about the switch idea, but that might be very very cool even if I have the AC fixed. I'll check that out
Thanks, need to read through these now before I can comment.
And yes, R12 is what I meant to type =\
Didn't know about the switch idea, but that might be very very cool even if I have the AC fixed. I'll check that out
Thread Starter
Seasoned Member
Joined: Jan 2009
Posts: 454
Likes: 0
From: Middle Tennessee
Year: 2001
Model: Cherokee
Engine: 4.0L I6
Certainly!
The e-Fan is driven by a Logical OR setup - EITHER the AC REQ signal is sent by the ECU OR the TFS in the driver's side radiator tank closes (or both.)
If you want to be able to "force" the switch on, you simply branch the latter input to make an EITHER-OR-OR circuit. Get a mating pair of Dephi Weatherpack connectors. (I'm going off of the presumption that your rig is the 1990 described in your post...)
You'll make a jumper using 18AWG wire between the connectors - but you'll also have a "tail" off of one side (again, 18AWG is just fine) that you can run into the cabin. I got two pairs of Weatherpacks - one pair for the jumper proper (plugs in between the TFS and the harness connector, one pair for the Wye branch) to simplify things. I also used 18/2 SJOOW from the hardware store - same reason. The 18/2 will have two 18AWG leads in a common overjacket, the wiring is quite flexible, and the overjacket is water-/oil-/grease-resistant. I've been using it underhood for years.
Anyhow, run the 18/2 into the cabin so that it may be connected to a switch at a convenient location - toggle, or an ON-OFF (not momentary - you need a "click" type) pressbutton swtich. The switch merely needs to be rated for 500mA or so - not much.
Turning the switch ON will force the e-fan ON. Turning the switch OFF restores normal operation of the e-fan. If the switch is ON and you turn the key OFF, the fan will also turn OFF (you're not bypassing anything to provide power.)
You have have an EITHER-OR-OR setup - EITHER the AC REQ signal turns the e-fan relay on, OR the TFS turns the e-fan rely ON, OR the toggle switch you've just installed turns the e-fan relay ON. All three signals go to the same relay, and you won't need to add fuses or worry about running a large current anywhere.
Pass the 18/2 SJOOW through a convenient grommet in the firewall.
The e-Fan is driven by a Logical OR setup - EITHER the AC REQ signal is sent by the ECU OR the TFS in the driver's side radiator tank closes (or both.)
If you want to be able to "force" the switch on, you simply branch the latter input to make an EITHER-OR-OR circuit. Get a mating pair of Dephi Weatherpack connectors. (I'm going off of the presumption that your rig is the 1990 described in your post...)
You'll make a jumper using 18AWG wire between the connectors - but you'll also have a "tail" off of one side (again, 18AWG is just fine) that you can run into the cabin. I got two pairs of Weatherpacks - one pair for the jumper proper (plugs in between the TFS and the harness connector, one pair for the Wye branch) to simplify things. I also used 18/2 SJOOW from the hardware store - same reason. The 18/2 will have two 18AWG leads in a common overjacket, the wiring is quite flexible, and the overjacket is water-/oil-/grease-resistant. I've been using it underhood for years.
Anyhow, run the 18/2 into the cabin so that it may be connected to a switch at a convenient location - toggle, or an ON-OFF (not momentary - you need a "click" type) pressbutton swtich. The switch merely needs to be rated for 500mA or so - not much.
Turning the switch ON will force the e-fan ON. Turning the switch OFF restores normal operation of the e-fan. If the switch is ON and you turn the key OFF, the fan will also turn OFF (you're not bypassing anything to provide power.)
You have have an EITHER-OR-OR setup - EITHER the AC REQ signal turns the e-fan relay on, OR the TFS turns the e-fan rely ON, OR the toggle switch you've just installed turns the e-fan relay ON. All three signals go to the same relay, and you won't need to add fuses or worry about running a large current anywhere.
Pass the 18/2 SJOOW through a convenient grommet in the firewall.
Whao 5-90, that's a rad writeup. Makes a lot of sense too. (Yes, this is my old '90 renix I'm working on).
I'm going to check into that suggestion and see if I can't make that work
CF Veteran
Joined: May 2008
Posts: 3,018
Likes: 23
Year: 1988
Model: Cherokee
Engine: AMC242
It will work, if you do your job properly. I've had five RENIX rigs, did this to four of them (the other one was an AX-15 transmission I picked up and drove home. Gotta get around to disassembling that beastie one of these days...)
Thread
Thread Starter
Forum
Replies
Last Post
Aryl
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
12
May 5, 2024 10:29 PM
Rotorhead
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
20
Sep 23, 2023 04:17 PM
Chick-N-Picker
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
21
Aug 27, 2015 12:27 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)