Coolant Fan Temp Switch Disonnect?
Thread Starter
Racer
Joined: Jul 2002
Posts: 474
Likes: 1
From: Wake Forest NC
Coolant Fan Temp Switch Disonnect?
The shop manual for my '88 indicates that the first step in checking out the Aux Cooling fan circuit is to take the connector off the coolant fan temp switch and grounding the dark green/white wire. I feel really stupid, but I can't figure out how to do the disconnect. I popped off what I thought was holding it on (see pic) but it still doesn't come off. I don't want to force it. How do you get the darn thing off?
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
See the rectangular tab on the side of the connector at 1 o'clock.
There is a matching one at 7 o'clock.
Use thumb and fore-finger to gently squeeze together here and the
connector should easily slide off the terminal end. If not, something
is not right - do not force this or you will need to replace parts.
.
There is a matching one at 7 o'clock.
Use thumb and fore-finger to gently squeeze together here and the
connector should easily slide off the terminal end. If not, something
is not right - do not force this or you will need to replace parts.
.
Thread Starter
Racer
Joined: Jul 2002
Posts: 474
Likes: 1
From: Wake Forest NC
Thanks
Thanks for the info and comments on the engine. I'm doing an NCRS Performance Verification on the car next month. Got to make sure everything works. According to the shop manual the aux fan is supposed to come on above 228 degrees. That's when my main fan comes on. I've never seen the aux fan come on. I know the motor is good. The shop manual also indicates that both the aux and main fan relays are near the master cylinder. There are two there, but only one is a fan relay. I found out the other relay is on the fan shroud, but wasn't sure which one it was so I appreciate the extra info. Much easier to test it there. 
Last edited by routesixtysix; Apr 18, 2007 at 10:36 PM.
Burning Brakes
Joined: Dec 2005
Posts: 998
Likes: 0
From: Indianapolis IN
I do believe the previous owner of mine grounds the fan.
He cut the green/white wire on the drivers side and one spot is just sitting there. Then the other end goes into his yellow wire and he has a screw holding it up to a piece of metal where he drilled a hole. I plan to undo that and strip the wire back down, stick in a new section and wire it back so it can kick on and off like normal.
He cut the green/white wire on the drivers side and one spot is just sitting there. Then the other end goes into his yellow wire and he has a screw holding it up to a piece of metal where he drilled a hole. I plan to undo that and strip the wire back down, stick in a new section and wire it back so it can kick on and off like normal.
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Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Thanks for the info and comments on the engine. I'm doing an NCRS Performance Verification on the car next month. Got to make sure everything works. According to the shop manual the aux fan is supposed to come on above 228 degrees. That's when my main fan comes on. I've never seen the aux fan come on. I know the motor is good. The shop manual also indicates that both the aux and main fan relays are near the master cylinder. There are two there, but only one is a fan relay. I found out the other relay is on the fan shroud, but wasn't sure which one it was so I appreciate the extra info. Much easier to test it there.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Actually the Shop Manual shows 228. I test mine by putting the nose up against the garage wall when it's 90 or better and with the a/c off I can sometimes get it to reach the threshold for operation. Otherwise, it should never come on. A $100 moneymaker for GM - plenty of Vettes came without it.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Actually the Shop Manual shows 228. I test mine by putting the nose up against the garage wall when it's 90 or better and with the a/c off I can sometimes get it to reach the threshold for operation. Otherwise, it should never come on. A $100 moneymaker for GM - plenty of Vettes came without it.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
I don't know if it was changed - I don't have access to a Shop Manual below '88 and for that, the Main is 226; Aux is 228 and that's what my '89 Manual shows too. Someone posted the '90 and '91 and if I remember it right, it was fairly close to these #'s. My neighbor is a Mitchell Dealer and his software showed that the LT's had something like a 217 or 219 Main and a 226 Aux, but I posted that once and was reamed out fairly well (though I think Alldata has those temps too). I never turn off the a/c so mine is usually running shortly after startup and I average about 205 to 212 in traffic (which is how it was when I bought it new). The only time it gets to 226 is when it's smogged and it usually leaves the station at about 217 and then drops 5 to 12 degrees when I flip the a/c back on.
Thread Starter
Racer
Joined: Jul 2002
Posts: 474
Likes: 1
From: Wake Forest NC
Like I indicated, I've never seen the aux fan come on. I've had the car since new, and when I asked the service dept. about it then, they told me that under normal circumstances, it should not come on. I guess if it aint broke, don't try and fix it!
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Except that your Main should be coming on at 226 (a/c off), but the signal is from the Engine Coolant Temp Sensor so you would need to scan it to see if it's working correctly. Your dash is from a sender in the right head and it wouldn't be unusual for it to be a couple of degrees higher. Otherwise, a/c operation will have the Main cranking with a high side pressure of 220 psi and cycling off when it drops to about 190 psi, regardless of engine temp. If the system is right, coolant temps will be a few degrees cooler with the a/c on because the fan is running longer to keep cool air coming out of your vents (and the system from blowing a hole in your hood).
