AC Cooling Fan not turning on....

Okay, I've replaced the fan, the thermostat, thermostat sensor, and the cooling fan rely. I had the radiator flushed and filled with coolant done by jiffy lube. I checked the fuse. It's good.

What next? :banghead:

Thanks

Also, I start the jeep, let it get to regular temp, (210) and I turn on the AC. Nothing. It stays at regular temp but if I drive in slow traffic it runs hot. I turn on the AC, it doesn't blow cold air. Do I need a new radiator? There was rust in the radiator. Could it be the water pump?

Okay. I've learned today that it's not an AC cooling fan but just a cooling fan. It over heated today at lunch. I either need this fan to work or replace the radiator.

If this fan worked, would I still overheat? Can I just wire this new fan to a switch in the dash and manually turn it on?

What the best thing I should do? HELP!!!:confused:

Okay. I've learned today that it's not an AC cooling fan but just a cooling fan. It over heated today at lunch. I either need this fan to work or replace the radiator.

If this fan worked, would I still overheat? Can I just wire this new fan to a switch in the dash and manually turn it on?

What the best thing I should do? HELP!!!:confused:

You should start by telling us what year it is.

2000 Jeep Cherokee 4.0L Sport

Have you checked the fuse, and after that, checked to see if voltage is going to the fan?

Have you checked the fuse, and after that, checked to see if voltage is going to the fan?

I did and the fuse is good. voltage is NOT goning to the fan. So I disconnected the senso that is located on the thermostat housing, the fan turns on. And the check engine lights comes on and the temp gauge doesn't work. And when I reconnect the switch, the fan shuts off. I'm guessing that it's the switch that opens the electrical curcit to tell the fan to turn on.

I just replaced that sensor yesterday. Is it a bad one? Or the wrong one? Could the thermostat be installed incorrectly or be the wrong one? I was told there are 3 different levels of temp gauge for all thermostats. Maybe this one lets the engine run hotter at 220 or more? But like I said, I drove it yesterday at lunch and it over heated. Well I pulled over and turned it off as soon as it went full temp.

I'm not the best electronics guy...but... you said when you disconnect the sensor the fan comes on, and it shuts off when you reattach it. Is it possible to reverse the wiring on the sensor? If not, then I'd think the sensor is bad.

I'm not the best electronics guy...but... you said when you disconnect the sensor the fan comes on, and it shuts off when you reattach it. Is it possible to reverse the wiring on the sensor? If not, then I'd think the sensor is bad.

Makes sence. I'll try that. Or spend $70 on an OEM sensor.

Thanks. I'll let you know if that works.

Yeah, let us know.

On the 2000, the fan is controlled by the ECU. Removing the connector is supposed to turn the fan on. The sensor on the thermostat sends the signal to the ECU. The ECU interprets the signal and controls the temp gauge, fan operation and engine management (fuel and ign).

Normally the fan won't kick in until the engine temps reaches 220-230 ish. Or, with the AC on, when the high pressure line exceeds somewhere around 280 psi (I don't recall the exact numbers).

So how hot is hot? 210ish is normal. Getting hotter when driving slow could be a partially clogged rad, or a worn out mech fan clutch (more likely). Does it cool off if you drive faster or shift to neutral and rev the engine?

Your AC may be blowing warm because it may be low on refrigerant.

very helpful info. Thanks.

Yesterday it ran one line past the 210 middle (normal) point. I was driving 60 mph on the freeway. Then when I pulled off it overheated in about 3 mins of driving 25 mph. Fan never kicked on. Today, the fan kicks on when I turn on the AC which it didn't yesterday.

I think you are right on with a partal block in the radiator. I hope it's not the water pump. I'm having it checked out today by a professional.

YEAH IT'S FIXED!

I replaced the fan first. And I was the problem. I didn't remove the plastic piece that was in the original fan connection housing. So it never was getting a good connection. Once I pulled that out, that fan kicked on just like everyone said. At 220 temp or when I turned on the AC.

Thanks!

Stupid me, but lesson learned.

pahtnah:

What temp does your Jeep run at now that you got the problem fixed? How hot will it get before the new fan kicks in?

Mine runs about 190... if I'm in heavy traffic or idling it will get to about 220 until the fan kicks in. Sounds about the same as yours, but I wanted to see what temp you were running at now with the new fan?

Saudade:

When mine runs a little warm it will cool off when its up to speed, and also if I rev in neutral. What does that mean?

pahtnah:

What temp does your Jeep run at now that you got the problem fixed? How hot will it get before the new fan kicks in?

Mine runs about 190... if I'm in heavy traffic or idling it will get to about 220 until the fan kicks in. Sounds about the same as yours, but I wanted to see what temp you were running at now with the new fan?

Saudade:

When mine runs a little warm it will cool off when its up to speed, and also if I rev in neutral. What does that mean?

Sounds to me like it's working fine.

When you rev in neutral, you increase the coolant flow (waterpump turns faster), so it cools better. The mech fan also spins faster and pulls more air through the rad. When you're moving, there is more air flowing through the entire radiator.