I have an '02 Camry (4cyl) with radiator fans that died. I replaced the unit, but the A/C fan will not come on. (I checked and both fans will power up). I have yet to check the relays in the junction box, but if they are good, what sends the signal to the fan to turn on when the A/C is switched on ? The A/C works fine when the car is moving and air is coming across the condenser. Any suggestions ?

 

The fan circuit is somewhat complex having 3 relays.

Power to the AC fan motor is via the No 3 fan relay. One terminal of this relay solenoid coil is always hot when Ig key is on, powered by the 10A Fan RLY fuse via the IG1 relay.

The grounding of the other terminal to the solenoid coil completes the circuit to energize the coil which turn on the relay switch.

This ground circuit can be completed by:

The No 2 water temp switch closing.
AC compressor magnetic clutch relay.

Power for the AC fan motor comes from the 30A CDS fuse via the fan No 3 relay contacts.

However. The negative wire of the AC fan motor does not directly go to ground. It goes to the relay contacts of the No 2 relay. When this relay is energized the ground circuit is complete.

The No 2 relay solenoid is power by the same source as the No 3 relay solenoid.

 

Hey Joey P,
Thank you so much !

That's a lot of tech info and I believe it to be a fairly simple issue since the fan should come on when the A/C comes on. I'll check the relays right away. I was a llittle concerned that BOTH fans should fail at about the same time. The car only has 137K on it, but it has been just about flawless so far.

I'll let you know what I find out. I assume I can just make the connection on the #2 water temp sensor and force the fan on to check it.

Don

 

Doubt both fans failed. Most likely a relay or some other common issue to both fans.

If the wire to sensor 2 is grounded and the system is working OK, the fans should turn a the low speed setting.

The fans run in series at low speed and parallel at high speed.

 

It surprised me also that both fans would die at about the same time, but I put power directly to both fans when I replaced them and they were dead.

I couldn't replace the relays last night (or check them since it got too dark), but I did notice there were several dupicates in the junction box. I swapped relays on two of the fan relays and will play with it more this weekend. I didn't know the fans could run in parallel or series (pretty slick).

The radiator fan now comes on. If I can start the A/C fan from it's relay, yet it still doesn't come on when the A/C is turned on, do I have an issue further upstream in some control computer module ? I really don't want to spend $108 for Toyota to diagnose (only) the issue, but summer is hot in Texas and I have to get A/C on my parent's car working before they melt...

Thank you for all your help !
Don

 

With AC On the fans will only run when the compressor is running (the magnetic clutch is engaged). Thus the fans will cycle on and off with the compressor.

Send a private message with your email address. Will reply with a wiring diagram that also has a good deal of operational data. One wiring diagram is worth a thousand words.

 

SUCCESS !!!

OK, so what do they say about the simplist solution usually being the correct one ?

I was getting a bit frustrated since the relays were all checking out when the thought hit me that maybe I had burned out the new fan. So I thought I'd hot wire it to double check (I also did this before I installed it). What the heck ! It was dead also ! No, wait, one of the new little spade tips had just broken off in the plug head. Well darn... I'll just splice the old plug in if I have to. Wait a minute... is the spade still in there... but pushed in to the plug body ??!! A pair of needle nose got the spade out. Seems the spade pushed through the plug body when I first installed it. I took care to make a better connection and the whole system is fine, my parents have AC for the Texas summer AND I got a meal out of it.

I'm still a bit surprised that both fans failed at about the same time (I checked them again also), but all seems OK now.

Thanks Joey P for your diagnostic help.

Don

 

Great job!. Thanks for posting back with the results.

 

Its nice to see that u have posted the solution for fan burn out and i too had the same problem before but now its k my AC in my car is working in good condition....

 

I am also having the same trouble with my 99 camry. All the relays checked out ok and the condenser fan works when connected directly to the battery. The radiator fan works fine.