89 LXi radiator cooling fans won't come on

[rebuild]

89 LXi radiator cooling fans won't come on but both fan motors work. I don't know if the fan problems are related or if they are independent of each other. I haven't started swapping coolant temperature sensors yet. I have the blower motor and evaporator out of the car - the A/C system is open. The troubleshooting flowcharts in the service manual mention whether the A/C clutch operates normally with A/C switch - can I test that alright with the A/C system open?

Any ideas? Thanks.

The car had been sitting for a number of months.

[Dr_Snooz]

I'm not understanding the question. If the car is just sitting (not running), how do you know the cooling fans are not working?

[zenapup]

I think so, but you would need to remove the fuse for the rear defogger (#5 in the underdash fusebox) to keep the pressure switch from blowing the fuse due to no pressure in the A/C system. You do however, need the blower motor because you need to turn the fan on to make the A/C come on and thus turn on the cooling fans. Hope this helps.

[lostforawhile]

I think so, but you would need to remove the fuse for the rear defogger (#5 in the underdash fusebox) to keep the pressure switch from blowing the fuse due to no pressure in the A/C system. You do however, need the blower motor because you need to turn the fan on to make the A/C come on and thus turn on the cooling fans. Hope this helps.

huh? the pressure switch does not BLOW the fuse it opens the compressor clutch circuit, and doesn't allow the clutch to engage, why do you think the blower motor needs to be there to make the cooling fans come on? the AC circuit simply provides an additional ground to the existing thermoswitch circuit

[lostforawhile]

the electrical diagrams are available to download on the three geez wiki, once you see the fan control circuit on the LXI vs the DX you will want a DX, way too complicated

[ecogabriel]

the electrical diagrams are available to download on the three geez wiki, once you see the fan control circuit on the LXI vs the DX you will want a DX, way too complicated

Agreed. LX-i has TWO fan switches.

But if the electric fans do not come on when the engine is hot, I would look at the one in the radiator (lower tank) and try bridging the connector; that should turn the fans on immediately (assuming your car keys are in the ON position). If it does not, get an electrical diagram and start looking for other issues (relay?)

The SECOND fan switch is in the thermostat housing beside the ECT sensor (the fan switch is the BIGGER of the two). But that makes the smaller fan come on with the engine is stopped AND temperature reaches over 100 degrees celsius (it is marked "104").

[rebuild]

ESP Dr. Snooz. The car WAS sitting - past tense. I'm trying to get it ready for a long trip, so I have taken short trips in it lately and this morning drove it about 50 miles - with the fans out of it - no problem. It seemed to be the fans because I haven't been hearing them and because of when the temp gauge climbs at stop lights and after the car is off. Under a load like going uphill on a hot day, the temp gauge starts to climb as well so I am wary of crossing the mountains till I get this resolved. I've got my multimeter now. I didn't know if when a car sits with no coolant or rusty coolant, if the temp sensors are prone to going bad (nice to know if I find some sensors in the junkyard). I wouldn't mind the simplicity of a DX or LX, but I would miss the sunroof too bad. Does it take 500K to start to break in the engine on those models too?

Ecogabriel - are you saying to apply voltage to the sensor connector and that should immediately turn on whichever fan? That sounds like a lot more fun than pulling the sensors and heating up water. I thought the radiator sensor controlled the condenser fan? I will look over the connector pinouts. That's a nice test if it quickly tells you if you need to swap the sensor and which one.

I don't think the local car parts stores differentiate temp sensor A and B with different temp trigger points though - I think they sell one for all.

Found my A/C diode, but not sure how to get it off.

Thanks all.

[ecogabriel]

ESP Dr. Snooz. The car WAS sitting - past tense. I'm trying to get it ready for a long trip, so I have taken short trips in it lately and this morning drove it about 50 miles - with the fans out of it - no problem. It seemed to be the fans because I haven't been hearing them and because of when the temp gauge climbs at stop lights and after the car is off. Under a load like going uphill on a hot day, the temp gauge starts to climb as well so I am wary of crossing the mountains till I get this resolved. I've got my multimeter now. I didn't know if when a car sits with no coolant or rusty coolant, if the temp sensors are prone to going bad (nice to know if I find some sensors in the junkyard). I wouldn't mind the simplicity of a DX or LX, but I would miss the sunroof too bad. Does it take 500K to start to break in the engine on those models too?

Ecogabriel - are you saying to apply voltage to the sensor connector and that should immediately turn on whichever fan? That sounds like a lot more fun than pulling the sensors and heating up water. I thought the radiator sensor controlled the condenser fan? I will look over the connector pinouts. That's a nice test if it quickly tells you if you need to swap the sensor and which one.

I don't think the local car parts stores differentiate temp sensor A and B with different temp trigger points though - I think they sell one for all.

Found my A/C diode, but not sure how to get it off.

Thanks all.

#1. Temperature in mine also climbs when stopped on traffic lights or in heavy traffic; however, when about 2/3 of temp scale both fans kick in. That does not happen when I drive with the A/C on (both fans are on then)

#2. NO VOLTAGE should be applied to the sensor. Remove the connector from the sensor (look it up in the radiator's lower tank, can't recall exact location) and connect the terminals inside the connector with a piece of wire; with the engine on, the fans should come on immediately.

You may want to do the same with the sensor on top of the engine if you like, although that circuit only works with engine OFF to limit heat soaking - the smaller fan would come on and stay on for some time (up to 15 min),

[DBMaster]

Interesting thread, from the standpoint that my auxiliary fan (the smaller one on the D/S) hasn't come on after engine shutdown in years. I remember it running in the past when the outside temps exceeded 100 F. I replaced both of the temp switches on the thermostat housing a number of years ago and replaced the actual connectors. My connectors were not salvageable due to the wires cracking right at the connectors. My mechanic let me cut newer ones from his wiring harness collection. My current connectors have been soldered to the original harness. My belief (note I said MY) is that the current synthetic oil I am using combined with a better (all aluminum) radiator has resulted in better cooling to the extent that I no longer reach a temperature that requires the small fan to run after the engine is off. Keep in mind that I last replaced my radiator in 2003 and my engine has 353,000 miles on it. My foot only seems to know two positions, off the gas pedal and gas pedal to the floor. As all of you know, "to the floor" is the only position that gets you decent acceleration.

I have considered the possibility that I have an issue or failure somewhere, but I guess after nine years I would know if the failure of the fan to run after engine shutdown was a problem - or not.

[ecogabriel]

Interesting thread, from the standpoint that my auxiliary fan (the smaller one on the D/S) hasn't come on after engine shutdown in years. I remember it running in the past when the outside temps exceeded 100 F. I replaced both of the temp switches on the thermostat housing a number of years ago and replaced the actual connectors. My connectors were not salvageable due to the wires cracking right at the connectors. My mechanic let me cut newer ones from his wiring harness collection. My current connectors have been soldered to the original harness. My belief (note I said MY) is that the current synthetic oil I am using combined with a better (all aluminum) radiator has resulted in better cooling to the extent that I no longer reach a temperature that requires the small fan to run after the engine is off. Keep in mind that I last replaced my radiator in 2003 and my engine has 353,000 miles on it. My foot only seems to know two positions, off the gas pedal and gas pedal to the floor. As all of you know, "to the floor" is the only position that gets you decent acceleration.

I have considered the possibility that I have an issue or failure somewhere, but I guess after nine years I would know if the failure of the fan to run after engine shutdown was a problem - or not.

My wires cracked exactly the same way as yours; I got connectors from the jy as spares, but I cut long enough wires from the harness to take my connectors apart and solder the still flexible portion of the wires (the ones inside the harness) to the contacts, and then reassemble them.

I further protected each wire with shrink wrap in the section where they were unprotected before, and then added regular wrap on top of the shrink wrap. The wires then got soldered to my engine harness. I do not think they would crack again.

My auxiliary fan rarely comes on; I just caught it ONE time. I also replaced all temperature sensors, and the radiator (had a crack on the top tank) with a pristine (aluminum still shining) used radiator I found in the jy.

Funny your take on the bimodal accelerator pedal: OFF - ON

[rebuild]

ecogabriel you were so right - both my sensors failed the connector jumper test and the one on the radiator does control the main fan like you said. it takes a 22mm which i need to find though. am sensor shopping right now. think i should change the tw sensor/switch while i'm at it? does that one throw an engine check light if it starts to fail?

thanks a bunch

[lostforawhile]

ecogabriel you were so right - both my sensors failed the connector jumper test and the one on the radiator does control the main fan like you said. it takes a 22mm which i need to find though. am sensor shopping right now. think i should change the tw sensor/switch while i'm at it? does that one throw an engine check light if it starts to fail?

thanks a bunch

does the fan come on when you jump the sensors? if t doesn't come on when you jump either one then it's the control module or something going to it, the fan should run when you jumper it.

[Oldblueaccord]

Interesting thread, from the standpoint that my auxiliary fan (the smaller one on the D/S) hasn't come on after engine shutdown in years. I remember it running in the past when the outside temps exceeded 100 F. I replaced both of the temp switches on the thermostat housing a number of years ago and replaced the actual connectors. My connectors were not salvageable due to the wires cracking right at the connectors. My mechanic let me cut newer ones from his wiring harness collection. My current connectors have been soldered to the original harness. My belief (note I said MY) is that the current synthetic oil I am using combined with a better (all aluminum) radiator has resulted in better cooling to the extent that I no longer reach a temperature that requires the small fan to run after the engine is off. Keep in mind that I last replaced my radiator in 2003 and my engine has 353,000 miles on it. My foot only seems to know two positions, off the gas pedal and gas pedal to the floor. As all of you know, "to the floor" is the only position that gets you decent acceleration.

I have considered the possibility that I have an issue or failure somewhere, but I guess after nine years I would know if the failure of the fan to run after engine shutdown was a problem - or not.

Mine never come on either. The only times they do is after a shut down at pretty high altitude and hell that has been years. if you watch your temp gauge after a shut down my car doesn't go up it holds or goes down.

I run the fans with out AC by pulling the ac fuse. I like to control them manually when I run the Dragon tail and be able to run them some(forced on) when I am off taking a break. I just turn the blower fan on the first click with the AC button on.

wp

[ecogabriel]

does the fan come on when you jump the sensors? if t doesn't come on when you jump either one then it's the control module or something going to it, the fan should run when you jumper it.

The fans (both) should run when you jump the connector that plugs in the radiator sensor IF your car's ignition is in the ON position.

[rebuild]

DBMaster - where'd you get that all-aluminum radiator that fits?

I swapped two sensors - the one in the radiator and the TW sensor. I didn't have time to wait for the other coolant temp sensor to come in before I left on this trip. The one in the radiator came out easily. The replacement would not tighten down but is in there fairly firm. You can still turn it but it's not real loose, but it doesn't seem to work. Had to take the car for a 1,200 mile spin. The jumper wires keep it from overheating. Think I got a bad sensor? Need different radiator if sensor can't tighten down? Thanks.

[lostforawhile]

The fans (both) should run when you jump the connector that plugs in the radiator sensor IF your car's ignition is in the ON position.

and if you jump the other one with the car off I believe one fans runs, it's on a timer so that triggers the time cycle, it only comes on when you turn the car off with it really hot

[ecogabriel]

and if you jump the other one with the car off I believe one fans runs, it's on a timer so that triggers the time cycle, it only comes on when you turn the car off with it really hot

You are right; the smaller fan (driver's side) is the one that runs when the connector in the thermostat housing is jumped... why they did it so f... complicated with timer and everything?

[ecogabriel]

DBMaster - where'd you get that all-aluminum radiator that fits?

I swapped two sensors - the one in the radiator and the TW sensor. I didn't have time to wait for the other coolant temp sensor to come in before I left on this trip. The one in the radiator came out easily. The replacement would not tighten down but is in there fairly firm. You can still turn it but it's not real loose, but it doesn't seem to work. Had to take the car for a 1,200 mile spin. The jumper wires keep it from overheating. Think I got a bad sensor? Need different radiator if sensor can't tighten down? Thanks.

So, your fans work when the connector is jumped? If they work, then the sensor is the problem. If you have a multimeter, set it up on the ohms scale to measure continuity and connect each end to each contact in the sensor. Then heat some water until it almost boils and submerge the part of the sensor that goes inside the radiator; the multimeter should show continuity after a few seconds. Otherwise, the sensor is defective.

I do not get how the replacement would not tighten; you do not have to over-tighten it because the threads are more likely plastic, but it should tighten. Otherwise, it may become loose once the cooling system gets pressurized (engine to normal operation temperature)