02 Eldo ESC gets close to overheating

[CadVetteStang]

Not low on coolant. The norm for the last 6 months has been just above halfway on the temp gauge due to crank sensor issues and a check engine light. Also now low on Freon so computer shuts AC off and gives me a text message on the dash.... No problems when driving at any speed above 20 MPH. However, when sitting in a drive thru line, the temp gauge begins to rise.

It has not overheated yet, but it had been 3/4 to the red mark (where I either shut it down or start driving )

I listened for the fan motor, but don't hear it running. However it does seem to turn at a slower speed.

It it a simple, the main fan motor is bad - fix it, issue, or is there a slow speed or other sensor issue that may be going on? I don't have the money to just start changing parts till I get the right one. I need to nail it on the first try.

And to be sure, which motor is the non AC motor?

[rockfangd]

I believe the driver side fan is the engine fan and the passenger side is the a/c and backup fan. Makes me wish these analog ones had coolant temp readout already. I would like to know what the temp is getting to.

[Cadillac Jim]

Here is the data from the 1997 FSM section on Cooling fans, p. 6-797:
Fan Low speed will come on when any of these is true:

• Engine temperature is 229 F (106 C) or higher
• Transmission temperature is 302 F (150 C) or higher
• A/C is on
• Fans will continue run on LOW with key off if coolant is 304 F (151 C) or higher

Low speed will turn off when the engine temperature is 216 F (102 C) or lower.

Fans will run on High speed on when any of these is true:

• Engine is 234 F (112 C) or higher
• Transmission 304 F (151 C) or higher

Fan speed will go from High to Low when Coolant is 229 F (106 C) or lower.

So, with the A/C off and speeds too low to carry much air through the radiator, it is normal for the car to heat up to 226 F, the fans to come on Low speed, the engine to cool to 216 F, and then repeat the cycle. If the car is moving fast enough to keep the coolant below 226 F, the fans will stop coming on.

There was a Myth Buster episode which tested the idea that a car got better gas mileage with the A/C on and the windows closed than with it off and the windows open. They revisited the testing a couple of years later with better instrumentation because of controversy. The conclusion was that below 45 or 50 mph, a car will get better gas mileage with the A/C off and the windows open, but above 50 mph, you get better gas mileage with the windows closed and the A/C on.

There are three relays that control the fan speeds. On Low speed, the relays hook them in series so that they each have about 6 Volts across them. On High speed they both have full battery voltage across them.

If this is not what you are seeing with your fans, check the wiring harness, the fuses, and the connectors on the relays and the fans. Then, check the relays. Last, the fans can go bad, too, particularly if they have been physically damaged or something has obstructed the blades while they are on.

[CadVetteStang]

Thank you. This gives me a head start.