Renix thermal switch mystery...

Picked up an 88 for DD duties...

Temps climb while idling...

determined the electric fan does not come on even at 220*...

Switched the A/C on and turned the fan speed up and it does turn on...

Through research here, I figured it's probably the Thermal switch on the rad...

I looked...

I can't find it! I've looked on both sides of the rad but especially drivers side right above the lower return hose... Nada!

Nothing that has wires coming off it.

ideas?





p.s. My other '88 Pioneer's engine bay is quite different than this one. It seems to have a smaller main rad but an additional big cooler up front (tranny cooler?) I've seen a lot of oem tranny coolers that are long and narrow but this looks oem and seems quite larger... I also noticed while tracing a short circuit behind the dash that this one also has a lot more vaccum lines and gizmos behind the dash on the passenger side...

Trying to figure out what model this is... It's definately a Renix but previous owner badged it as an HO... WTF?


:dunno:

Factory a/c the switch is in the radiator, dealer-installed a/c the switch is spliced into the lower radiator hose.

I had a similar problem and it ended up being a faulty pressure cap. Make sure your cooling system is pressurizing!

Try this site. Just enter your VIN to determine model and year.

http://jeep.avtograd.ru/VIN/vin_en.asp

The switch is on the left side (drivers side) of the radiator on the back side (engine side) 3/4 of the way down. I had the same problem and ended up splicing in a switch so I could turn it on manually from inside the Jeep.

langer1 said:

Click to expand...

You mean here?



Is it missing? Did they replace the rad and not install the switch?

And yes the coolant bottle cap was a bit hinky...

Gonna try with the good cap from the other rig for a while.

Looks like it.

Simple fix - find the lead that was supposed to go to the TFS, get a Delphi Weatherpack to mate to it, and run the leads to a toggle or rocker switch mounted somewhere convenient.

Alternatively, just get the mating connector, use a short jumper, and short both terminals together. This will result in your fan running all the time, tho...

5-90

5-90 said:

Looks like it.

Simple fix - find the lead that was supposed to go to the TFS, get a Delphi Weatherpack to mate to it, and run the leads to a toggle or rocker switch mounted somewhere convenient.

Alternatively, just get the mating connector, use a short jumper, and short both terminals together. This will result in your fan running all the time, tho...

5-90

Click to expand...

Where does the TFS lead route from?

Do you have any pics of how you wired your switches? (I know you do it to all your Renix)

I don't mind keeping it eliminated and running a switch to the cab... That's how I wired it in the bigger rig... But I ran a hot lead off the battery with no relays to the in-cab switch and I'd rather do it right this time...

Electrical mods are NOT my forte...

It crosses under the radiator over to the relay panel.

It also goes here to the blue relay and the yellow diode block.

Gimme a bit, and I'll do some pix. They'll be with my Treo (so they won't be very good...) but you'll be able to see the mod in situ - which should help.

If all the original circuitry for the E-fan is in place, you won't have to do much - just pull two wires to somewhere convenient, and connect them to a switch. With the original relay in place (turning on the aircon does turn on the fan, right?) you don't even have to deal with high current - just a "trip" signal for the relay. Something like 18 gage wire should be just ducky (I usually use 18/2 SJOOW from the hardware store - so I only have to pull one wire. SJOOW is oil-resistant rubber-jacketed cable, and the "18/2" means there are two conductors in it, both 18AWG...)

5-90

5-90 said:

Gimme a bit, and I'll do some pix. They'll be with my Treo (so they won't be very good...) but you'll be able to see the mod in situ - which should help.

If all the original circuitry for the E-fan is in place, you won't have to do much - just pull two wires to somewhere convenient, and connect them to a switch. With the original relay in place (turning on the aircon does turn on the fan, right?) you don't even have to deal with high current - just a "trip" signal for the relay. Something like 18 gage wire should be just ducky (I usually use 18/2 SJOOW from the hardware store - so I only have to pull one wire. SJOOW is oil-resistant rubber-jacketed cable, and the "18/2" means there are two conductors in it, both 18AWG...)

5-90

Click to expand...

yes it does...

Ya...any pics appreciated... mainly interested in exactly where in relation to the relay to splice in...

and of course... which relay it is..



Thanks guys

Fan wiring.

Gil.

is the pigtail for the thermo switch there? If so....just install a new thermo switch.

If not..well then proceed as above, although I would also attempt to correct the cooling system....there sounds like trouble somewhere....crap in rad perhaps?

Rev

Rev Den said:

is the pigtail for the thermo switch there? If so....just install a new thermo switch.

Click to expand...

that'd be too easy...

I didn't see any with a cursory examination...

I wouldn't be surpised if they got sliced off... I mean who installs a rad and doesn't hook it up? The factory never did this right?

We're also talking about the Renix with HO badges...

oh and btw Rev... I took a closer look and they're American Racing not Centerlines.

The replacment radiator comes with a plug in the whole, so it's easy to overlook.

Gil,
this is an auto rig correct? I know that my 5spd no aircon Mj came with no aux cooling fan. I wonder if a factory 5 spd rig with aircon came with the fan but it was only wired to run with the AC.
It would be weird, but it was AMC.

Mine is a 5sp, and has the switch in the rad where Gil thinks it should be. However....it should be just fine without the electric fan as non-ac units did not have the electric fan. It ain't even hot yet Gil, me thinks you got other issues.

Rev

If it gets hotter sitting then it's also likely your therm fan clutch is bad.

I know it's not much of an issue in October round these parts...

but...

I'd hate to have it overcook while parked on the Edens for the daily crawl to Grayslake.

I know something's goofy because while I was hunting the short in the electrical down...I had it idling and then I happened to look at the temp gauge...

almost pegged to the right!

shut it down and peeked at the coolant bottle... sure enough... coolant oozing out the cap and where the hose connects to it on the bottom.

I let it cool down and restarted it (this time while keeping an eye on the gauge)... Electric fan never went on and I let it climb to 220*ish. Turned the controls to AC and turned the fan speed on and it turned right on.

That's why I'm guessing it's the thermo switch (or lack thereof!)

p.s. have had no cooling issues with it in motion-only while idling in park.
I also took another look under the hood and I found the ground (?) on the driver side fenderwall shown in this pic:



and I followed the wires from the fan snaking around the back of the engine bay and ending at the rearmost relay (where there's 4-5 of them)... If the fan comes on when the AC tells it to, that means the relay is good right?

The pointer was for something else, the blue relay shown is the fan relay, the thermo switch connects to it.