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Really confusing problem...

8984 Views 13 Replies 7 Participants Last post by  89aCuRa
I have a '91 LS, and am having a strange problem with overheating. After driving for about 20 minutes in slow-moving traffic, the temp starts to move up. When I accelerate, it begins to drop back down to normal. I've noticed that only one fan comes on, even when overheating, but both fan motors are good (tested with battery).

A mechanic at a dealership told me that when I turn on the A/C, both fans should come on, but neither does. All fuses are good. I assume it can't be the thermostat, because it doesn't completely overheat.

Does the temperature gauge read from the radiator sensor or the motor sensor?

I thought about replacing the relay(s), but don't know which to replace.

Anyone have any thoughts?
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i had this same problem, check the relays they might not be connecting correctly. my problem was the relay was pushing one of the connectors out of the was causeing it to not connect

also check for bad relays
There are 2 fan relays. 1 radiator fan main relay and 1 radiator fan relay. You deffinately have a cooling fan issue due to it only overheats when you slow down or stop. These relays are in the underhood relay box. You can swap them wit like ones next to them for troubleshooting. Swap them one at a time and see if the fans start working.
s55lear just had this same problem today in this thread.
Thanks for the replies.

The problem is that I don't know which relays I should be looking at. There are two relay boxes by the battery, one is long and rectangular, the other smaller and square (According to the Chilton manual, I'm looking for Box A). There is also a Relay box near the firewall on the passenger side.

I've found a few threads referring to the location of the relays using search, but the threads have been deleted.

Any ideas which relays I'm looking for?

Also, do I get them from the dealership or will aftermarket work?

Thanks again.
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abd this is where MikeD comes in.........

or kenso...
Miked had posted pics of all this but his pics won't work. You need some kind of manual. If you plan on maintaining your Legend yourself it's a must have.
The long rectangular closest to the radiator is the one where all the cooling fan relays are. Standing in front of the car you will see from your left to right, 3 big relays and 4 smaller ones. The 2nd big relay is the radiator fan main relay, swap it with the 3rd big relay which is the windshield wiper intermittant relay. Test drive it. If the fans work correctly and the intermittant wiper don't work correctly then you know what the problem was. If this is the case then swap them back and put the new relay in the radiator fan main relay position. I think you can get these relays at most auto parts stores.
Thanks JetDoc!

That's exactly what I needed. I am going to test right now.

I have a Chilton, but the relay location descriptions are vague at best.
I just switched the relays -- the fans still don't come on with the A/C on.

Considering the up and down idleing and white smoke, I don't think it matters much (BHG). I would, however, like to get as many miles as possible out of the car.

Anything else electrical I could check to get the fans working with the A/C?

Thanks!
Ok now we will swap the condenser fan relay.

These #'s will represent the relays. 1,2,3 are the big relays and 4,5,6 are the small ones. c is the red connector.

------6 c
1 2 3 4 5

4 is the condenser fan relay
5 is the radiator fan relay
6 is the horn relay

Swap #6 horn relay with #4 condenser fan relay. If no help try swapping #6 with #5.

Does your a/c work? does the a/c compressor come on when you select a/c?
If you don't have enough freon in the a/c system the condenser fan won't come on.
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Sure enough, I pulled the condensor fan relay and saw that it was blown. Replaced it with the horn relay and the fans came on as soon as I turned on the A/C. Didn't realize that the condensor fan relay would affect the two radiator fans.

On a side note, any recommendations on dealing with a BHG other than maintaining coolant and oil levels?

Thanks again! You've been a great help.
Did you try getting all the air out by doing this.......
Do this:
first turn the heat to full hot(opens the heater control valve to let coolant flow). *with ignition switch on.
1. Open bleeder at thermostat housing and remove radiator cap(not resivoir cap).
2. Pour coolant into radiator until a steady stream of coolant without bubbles comes out bleeder.
3. Close bleeder.
4. Leave rad cap off and start engine. As engine warms up top off coolant as air burps out.
5. Massage upper radiator hose to help get air out.*CAUTION COOLANT IS HOT AND WILL BURN YOU* if you squeeze the hose too hard and coolant splashes out on your arm.
6. When engine reaches normal temp it should be good to go. Install radiator cap.
7. fill coolant resivoir to proper level.
8. Drive vehicle and monitor temp. After engine cools down completely remove rad cap and top off if necessary.

If you are sure you have a BHG you can try removing the thermostat and operating without it. This will sometimes work until you can make repairs. The heat wont work very well and your gas milage will drop but you can still drive it.
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i got a simelier prolem on my 95 ls coupe but the heater motor fuse was missing so i put the rear def 40a fuse in and tryed post 2 no luck with post 1 the 4-6 swap worked but the horn worked also so it must have been a dirty conection thanks for explaning the relays my legend did not come with a manual:( il have to order one got a manual at the auction however after i did post 2 it worked for about 5 1/2 hours and then went back to 3/4 of the way up on my way back i havent overheated it any sugestions
95LSSIICOUPE said:
i got a simelier prolem on my 95 ls coupe but the heater motor fuse was missing so i put the rear def 40a fuse in and tryed post 2 no luck with post 1 the 4-6 swap worked but the horn worked also so it must have been a dirty conection thanks for explaning the relays my legend did not come with a manual:( il have to order one got a manual at the auction however after i did post 2 it worked for about 5 1/2 hours and then went back to 3/4 of the way up on my way back i havent overheated it any sugestions
Off subject but where in mass do you live?
i know this thread is old, but i want to link all fan problems so that when searched solutions can be found quicker. here is the link to my experience. my condensor fan relay that went out did not knock out the radiator fan. so i guess they can go bad without affecting the other fan. also when i put the bad relay that would not allow my condensor fan to work in the wipers relay, my wipers work but not in the fastest setting. so i guess it was partially blown, goodluck.

http://www.acura-legend.com/vbullet...-turned-passenger-side-fan-works-fine-123607/
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