S90 almost over heated...!

Post by **jimmy57** » 27 Jun 2013, 14:30

The fan relay has a two wire plug with small gauge wires. Ground one and you get low and ground the other and you get high. Key does not have to be on for this test.
The two wires in that gray plastic connector for speed control are "bullet" female terminals with the relay having male bullet terminals. There is plastic molded around the female and it disintegrates and the terminals don't like the battery acid environ there near battery. A battery change can easily disturb the connections.

anbran1 · Post by **anbran1** » 27 Jun 2013, 15:12

I'm not too sure which "terminal" you are referring to...
There are 3 plugs going into the relay...

Post by **precopster** » 27 Jun 2013, 16:25

The middle connector has Bullet connectors. The other 2 on each side are blade style connectors.

The plastic that disintegrates is around the connector to the centre terminals.

The part number is 9442933

anbran1 · Post by **anbran1** » 28 Jun 2013, 08:42

Is there a way to test the relay while it is off the car?

Post by **jimmy57** » 28 Jun 2013, 09:43

Use an alligator clip to provide power to the single copper blade terminal on left.
Ground one of the round terminals in center connector.
Probe with test light(be sure test light lead is grounded) the two terminals on right. One should light your test light. Now ground the other round terminal and the other terminal on right should light test light.

Or pull it off mounting in car and touch ground on those two terminals one at a time to see if fan runs on low and high.

anbran1 · Post by **anbran1** » 28 Jun 2013, 11:16

I've changed the relay (I had a couple of extra ones). I moved the ground location for the fan directly to the neg term on the battery to eliminate the potential for a bad ground...
I started the car and put the AC on...
With the engine cold like that, with the AC on, should the fan come on right away?! (Or does the engine have to get a bit warmer?

Post by **precopster** » 28 Jun 2013, 15:47

Hmm with the 850s and early V70s it's around a 10sec wait. Should be the same for you.

If you ground those terminals instead of allowing engine computer to do so does the fan come on? I mean grounding centre terminals with the connector off.

anbran1 · Post by **anbran1** » 28 Jun 2013, 15:58

I guess I'm a bit daft, but I'm confused by the term "grounding". I understand that to be "neg" terminal and the body ground related to it. If I attach a jumper wire to either of those middle connectors, where does the other end of the jumper wire go? Pos or neg?

Post by **precopster** » 28 Jun 2013, 16:12

Ground is definitely negative terminal. The term ground is also known as chassis on vehicles because the negative battery terminal is always connected to the body.

anbran1 · Post by **anbran1** » 28 Jun 2013, 16:25

Ok...I did it...and the fan comes on as you describe. Different speed for each terminal.
So I expect that that means the relay is good?!
Anything else I have to do? Not sure why the fan didn't come on for the AC.

S90 almost over heated...!

Re: S90 almost over heated...!