Cooling Fan not coming on

1996 Chevy Cavalier 2.2 lt engine.

Today i found, Cooling fan does not turn on even after reaching operating temperature.Engine overheats when idling. It does not turn on, when A/C is turned on ( I realized AC is also not working on my car, it may be related or not).

Only time it works is if i unplug the coolant/Engine temperature sensor.

I have checked the thermostat as it seems to open at right temperature, as both lower and upper hose feel hot at that point.

What has changed?

One month earlier,check engine light came on with code, P0304. I changed the Oxygen sessor and spark plug cables and that fixed the issue and car started working fine.

Yesterday,I have changed blower resistor as earlier my fan used to work only on 4th setting. After changing the resistor, all four speeds work now.

i did try by putting old resistor back to check if that solves the issue, the issue remains the same so again put back the new resistor.

Any help is appreciated

You seem to be confusing two fans.

The fan with the resistor pack is the cabin fan and it us used to provide cool or warm air to the cabin. The engine overheating might be caused by a problem with the radiator fan.

Can you separate those two fans and their related issues?

Since the fan runs when you pulled the connection to the temperature sensor it sounds like things are ok there. I assume the sensor connection you disconnected does not work with the dash gauge or the engine computer and if so it sounds like that sensor may be bad. I assume you are aware that the cooling fan does not normally come on until the engine temperature goes beyond a certain safe limit. Possibly around 205 degrees.

As for the AC problem I would first check for power getting to the system.

Do you have a fuse for that fan? Check it. Is fan connected? (I found a wire hanging off of mine before.) Disconnect fan and wire it directly to the battery to test the fan motor to see if that will make it work.

How exactly is the A/C not working - is it not cooling or the A/C clutch?

For my car there is a troubleshooting procedure to go through depending on whether the A/C clutch does not work and either 1 or both cooling fans do not work.

Sounds like you fixed a different problem with the new resistor. I just took my blower motor housing apart and my resistor looks somewhat degraded. Didn’t know you could get the resistor all by itself.

Thanks for your responses. i am replying to all the three posts here

  1. It is my radiator fan that is having the issue. I had provided information about the cabin fan just to make sure that we are aware of earlier issues that i tried to fix. For this post purposes, i am referring to my faulty radiator fan and all the information is regarding that.

  2. I am aware that radiator fan normally kicks in only if
    a. your engine temperature crosses the operating temperature of around 205.
    b. you turn on the A/C ( irrespective of engine temperature)
    My radiator fan is not working in either of these situations

  3. When the engine coolant temperature sensor ( which goes into engine block near the upper hose connection) is plugged out, these things happen
    a. Engine hesitates for two seconds and then radiator fan starts full blown
    b. Check engine light comes on ( which can be resetted later by detaching negative terminal and putting plug back in)
    c. Temperature gauze on the dial moves from 200 to 0.

These observations lead me to think that
a. Radiator fan motor is fine

What should be my next steps to resolve this issue?
Really appreciate your responses

New user error: wrongly clicked on the inappropriate flag as i wanted to edit the title

You have proven the fan motor is ok and most of the circuit for it is ok. You are either going to have to test the sensor that you temporarily disconnected to see if it meets specs or try replacing it and hope that fixes the trouble. It seems to me replacing it will solve the trouble.

i know this was ages ago but my 97 cavalier doing exactly what yours was, did u ever find the problem???