1985 Overheating Problem

[Tom T]

Help....working on a 1985 vette with a 1988 vette engine. Vette shows 130K miles. Rad has been re-corded and cleaned. Installed new fan and replaced fan relay. Fan does not come on at all even when I turn the A/C on. Only time the fan comes on is when I jump the relay. All I want to do is get the fan running, stop the overheating and sell this baby so that I can start working on my 81 vette.....

 

[vigman]

Post's to read ( cooling fans & senders)

http://corvetteactioncenter.com/forums/showthread.php?s=&threadid=14978&highlight=Fan

http://corvetteactioncenter.com/forums/showthread.php?s=&threadid=14113&highlight=Fan

http://corvetteactioncenter.com/forums/showthread.php?s=&threadid=10513&highlight=Fan

http://corvetteactioncenter.com/forums/showthread.php?s=&threadid=8648&highlight=Fan


And yes there will be a pop quiz at the end of the reading session!


Vig!

 

[Tom T]

Still Hot , Hot , Hot

Tommy, thanks for your help with the overheating (no fan) issue. I jumped the fan relay and the fan came on. So I replaced the relay.....still no luck.. I replaced the temperature sender on the right side of the cylinder head behind the oil dipstick. Well, still no luck....I was going to replace the coolant fan switch which I thought was located on the left (driver) side of the head. No can do, can't located it even with my glasses on! I found what I believe is the coolant emp sensor in the front of the intake manifold. Well, when I look at it, it does not look even close to the coolant fan switch that I purchased from NAPA! Guess I must be confused....The temp sender I replaced on the right head was a perfect match. The coolant fan switch I purchased has a single round female plug. I switch/sensor I think I see has a different connection................I guess since the vette is an 85 and the engine is from an 88 vette , things may be a bit different.

Any more sugguestions? Thanks, Tom T

 

[vigman]

Hmmmmmmmm

The sender for the fan HAS to be ...either

Between Cylinders
1&3 ( 88 )
or
6&8 ( 84 ) on the head itself.

The ROUND connector is correct for the temp sender ( fan )Dark Green / White

The SPADE lug is for the temp sender (gauge)
Dark green

The one on the front of the manifold is for the cold start valve.

Keep looking... unless your problem is that the sender is MISSING and there is a plug in the head where the sender SHOULD go...

Do you have single or dual fans?
In you year there is a PUSHER fan mounted in FRONT of the A/C condenser have a look!
But, it was an OPTION!

Vig!

 

[Tom T]

Temp Sender

Hey Vig,
Glad you told me about the manifold sensor, almost removed it. There is a plug in the head between the 1 & 3 cylinders. So, I guess there plane and simply is no temp sender. Also now wiring for it. Now what do I do..............I hate sounding like an idiot! I know the fan is operative along with the fan relay. Could the fan relay connector be bad? should I replace it? I guess the next step is the shop. Sure do not want to do that since I am only trying to repair the problem so that the next owner when I sell it does not get any surprise's. (would like to but it on the market ASAP so I can start on my 81).

Tom T

 

[Tom T]

After Thought

Just thinking and could the A/C have something to do with it since the fan should come on when the A/C does, and it does not? I can't imagine that the sender could be missing, yet the fan was working in the past. Now, I know that I saw a plug in the block between the 1 & 3 cyl's. There are no other relays attached to the rad and no additional fan in front of the rad. Hummmmmmm!

 

[Baldie88]

You said you have an 88 engine. I had a similar problem with my stock 88. Fan didn't come on with the a/c. Replaced the high pressure switch on the a/c line (smaller one of the two on the line). Fan always works with the a/c now. Might want to try that. Worked for me. I've got the pusher/puller fan setup on mine.

 

[vigman]

A cheat!

http://corvetteactioncenter.com/forums/showthread.php?s=&threadid=14978&highlight=A/C


If you read the post...the object of the game is to pull the connector.. it will tell the ECM that the A/C is on & will crank the fan up!



Vig!

 

[vigman]

And........

Lets assume that the 88 sender was on the wrong side ( for the 85 )

I'll bet the orig owner pulled the orig connector.. and either cut it back or taped it out of the way... I would CLOSELY CHECK the areas around the wiring harness for the Dark green/White wire.

Vig!

 

[vigman]

One more thing

The replacement connector( female with pigtail ) is available at PEPBOYS!


Vig!

 

[maxrevs85]

Fan switch is on the pass side in the head . It has a round connector like the knock senser......on an 85....the stop setup ,the fan doesnt come on untill 228 degrees.....

 

[maxrevs85]

the senser on the driver side head is the Gage senser....temp

 

[vigman]

Thanx Max

Please confirm the wire color of the temp sender, and a pix or description of where the wire breaks out of the loom.


Vig!

 

[maxrevs85]

The wire for the fan switch/senser is black it is a little difficult for me to see. I believe it branched out of the main loom since the computor has the settings for the fans to come on at pre set temps. It of course is a neg ground and works off resistance. If i remember right it is jacketed with the plastic wire loom when it comes out of the main bundle. Dont know if this helps . All the wires are tucked behind the block and firewall .