High idle and engine fans

[Tucson Mike]

I have a 1990 Reatta convertible. I have 2 issues that may or may not be related. One is when I first turn on the car it idles very high. around 1800 to 2000 RPM. If I drive it around a bit, then stop and put it into park, the RPM's go back down to normal around 700/800 RPM's. 

The other issue is that the front engine fan (the pusher fan) wont go on at all when the engine gets hot. The back engine fan (the pulling fan) ONLY will come on if I turn on the heater/AC. Could this be the cooling sensor is not working? A bad wire or switch?

 

Thanks!

[Samakijoe]

I would see if the front fan is getting 12V.  Jumper 12v to see if it turns on.

The fans probably have two temp sensors running them...

Both of mine run when the A/C is on...

It's normal for the RPMs to up when the engine is first started..

How long does the high speed RPM last?

Edited September 22 by Samakijoe

[2seater]

The fans on a 90 operate in series for low speed and parallel for high speed. Three relays inside the underhood relay center operate the fans.

 

The idle speed needs a bit more detail and as mentioned above, some increase is normal on a cold start.

[Tucson Mike]

Thanks for the replies.

 

OK. All this must happen on hot days. The past few weeks it was in the mid to upper 80's when I started the car up and that is when it was high idling. Today the temperature was in the upper 60's and the start up idle was pretty normal. About 1000/1100 RPM's.   

 

Also, I drove the car around for about 15 minutes holding speed at 55 with the cruise control. Didn't need  the heater or AC on and the temperature held steady straight in the middle at 12:00 on the temperature gauge.  

I will try the jumper idea to see if that does at least turn on the front fan. I'll keep you posted.

 

Thanks!