hey fellas


I have a problem with my 88 TBI maro. when i start the car cold the fan is not running. But after it gets up to operating temp(witch is the first line on the temp gauge) the fann comes on and stays on until the car cools down. What can cause the fan to stay running like that. I changedd the relay. could the CTS sensor gone hay wire or do they have a back up fan switch?.



thanks for any info

 

Unless I read this wrong, I'm not sure that I see the problem. The fans are supposed tom come on and stay on until the car cools to the proper temp.

 

I'm also confused. It sounds like they are working the way they are supposed to.

 

I read this a couple of times, too. The fan probably shouldn't turn on when the dash gauge is at the FIRST indicator line. That's usually about 120°F. It's possible that the temperature gauge is not indicating correctly, and/or the CTS is failing. I'd start by diagnosing the dash gauge and sending unit, since they are notoriously unreliable. They give a general indication, but aren't calibrated like a laboratory instrument.

 

hhey guys

thanks for the replies. But i have fixed the problem. I changed the CTS sensor made no change. Then i checked the temp gauge to see if it was reading correct the difftrence is aboutt 10 degrees from the water temp at the radiator cap opening and what the gauge was showing. ( not bad at all ) the fan would come on and stay on at like 180 degrees. the fan circuit is not supposed to kick on until like 216-220 from what my service manual. so then i traced out the wiring diagram AHAH found my problem on the passenger side head there is a secondary fan switch to kick the fan on incase if the computer was to fail to start the fan.
so i replaced it ( It's a pain in the **** just like # 8 plug to change) changed it and now it works like a dream fan kicks on @ 218 F and shuts down @ 202 F thats what i could get from the temp reading at the cap opening


so remember that one it took awhile to find it but now everybody will know that sensor is there also the part# is a FS1 (gp sorrenson) picked it up at work. Advance auto for like 6 bucks

 

COOL! (Yeah, lame pun, I know...)

 

Just a small note here. The temp should be checked where the CTS is located, not in the radiator cap. They will be pretty close, but you will get a small difference. If you're checking the gauge accuracy, you should check it on the head where the gauge is installed, since that's where it's getting it's reading.

I do see that things were close enough for you to fix it though.