I have a strange problem with my radiator fan.

It will not work if both the low speed and high speed relays are present. If I remove the low-speed relay, the fan will work in high speed. If I remove the high-speed relay, the fan will work in low speed. The fan will not work at all if both relays are in. They obviously both work, just not at the same time.

Any thoughts on what could be causing this?

 

The fans are not supposed to work all the time. They are supposed to come on if certain coolant temperatures and certain operating conditions are reached. If there is a sytem failure, like a missing relay, the fan will kick in (fail safe). What you have described could very well be a perfectly operating system. You have not described any overheating so you havent told us about a "problem" yet.

 

Overheats when idling. Radiator fan never kicks in. Thermostat constantly blows shortly after being replaced, allowing heater to only function on max setting. ECT has been replaced. All fuses and relays are in working order. The fan will come on when the AC is turned on though, so that motor works too.

 

Found no edit button...

When simply idling outside of the house to test, I can take it from a fresh start in the morning to vigorously bubbling coolant tank in about 20-30 minutes, without the fans ever coming on.

 

how do u know its over heating? is the temp guage way over the middle in the red?

 

The temperature gauge rises, and gets to medium or so when the coolant tank begins to violently bubble and boil. You can easily hear it from inside the car. It popped the lid off the first time.

 

Let me clarify a few things for the car since its actually mine not my hubbys(Cheg) and Im the one working on it.

Its a 99 Sebring Convertible Jxi
The radiator fan does NOT cut on at all no matter how hot the car gets. Usually after about 20-25min on a warm day the car gets hot enough that the coolant reserve fills with boiling water/antifreeze nif the car is not shut off or if the heater is not turned on after about another 5-10min it will start erupting coolant out and spewing it everywhere and I mean everywhere. Yet the fan still never comes on.

I have checked the fuses and the relays, they are all good. The fan does come on when I cut on the a/c and it does come on when I remove one of the relays. The failsafe I guess you were talking about. So Im pretty sure its not the fan motor. I can keep the car from overheating right now if I turn my heater on high which isnt too bad since its still in the 60s around here but come summer when its 90f+ I dont think its going to work anymore to use the heater to help keep the engine cool.

I have changed the thermostat twice, flushed the radiator, and replaced the ETC sensor. Though to clarify above the thermostat has not blown. The A/C blower motor resistor has blown 3 times now and I will be replacing the AC Blower motor next before putting in yet a new resistor. This causes the a/c and heater on only work on the high setting. However I feel this issue is unrelated to the radiator issue unless all the wiring is just all jacked up.


There are no leaks anywhere I, my hubby, or my brother can find. There are no check engine lights on and no error codes from the car. I believe my next step is to test the thermostat control switch/coolant fan switch that goes into the actual fan itself.

So if anyone has any good diagrams/pictures of that or any clear how to videos that would be awesome.

PS an edit button would be helpful on these forums

Thanks in advance for your help

 

ok some basics u need to know then If u have 50/50 mis of coolant and water it will not start to boil until the temp is about 250 your car runs normal at 200 in that range so if its boiling out your needle will be way over the middle range. Second when a system is under pressure it also raised the boiling point of water. U will need to get any and all air out of the system and make sure u have a good radiator cap.
Fans for your car wont come on until 215. and a cool day of 60 will take a long time to reach 215 so I would be looking for air bubbles and a bad radiator cap to start.

 

Thanks. After I jump the fan switch if it appears it is working correctly i'll replace the cap and see if that fixes it. if it doesnt ill have the radiator flushed again.

If you think of anything else please let me know.

 

"I believe my next step is to test the thermostat control switch/coolant fan switch that goes into the actual fan itself."

The "switch" that controls the fan is called the "powertrain control module" otherwise known as the engine computer. It reads the ECT sensor and decides whether to turn on the fans based on that reading and whether you have the A/C on. In order to determine if there's a problem there, you'll need to be able to have an accurate reading of actual engine coolant temperature under pressure.