Radiator and blower motor fans run all the time?

QUATERR

MEMBER
2002 FORD FOCUS
1.8L
4 CYL
TURBO
2WD
MANUAL
220,000 MILES

The problem is, when I start the car both of the fans run all the time, I've checked temperature sensor, high pressure switch, wiring, fan resistor, relays. Everything looks fine but I'm getting out of my mind. The heater setting is set to face and floor, and heater fan is turned off so demist function can't work. I don't know what to do.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,912 POSTS

It sounds like the HVAC control module is bad. I would do a CAN scan first to confirm, you can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is one for about $99.00 if you need it:

https://amzn.to/3ZixY4v

Here is how to change the HVAC controller out if a code comes up for it. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)

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Sunday, June 25th, 2023 AT 11:58 AM

QUATERR

MEMBER
2 POSTS

I've checked HVAC controller too and it's not broken. I also have scanned my car with Forscan, and there are no DTCs at all.

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Monday, June 26th, 2023 AT 12:20 PM

KEN L

MASTER CERTIFIED MECHANIC
42,912 POSTS

Does the Forscan check the CAN? It sounds like you may have a bad ground to the HVAC controller. here are the wiring diagrams and a guide to help you check the wiring and grounds. Also, I have seen the control cable for the vent doors fail.

Please check out this video as well:

https://youtu.be/Kawt1EodtFI

and

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images (below). Please let us know what happens.

Images (Click to make bigger)