Aussi-66

Hi guys I have slipped across from the C1-C2 forum.
It is summer down here in Australia and it has been running 100 to 105 degrees out here in the boonies where I live. I had a friend on a road trip drop in to see me. Her C4 had boiled while driving through cities but was ok on the highway. A quick check showed the fan wasnt running, further checks proved that the fan motor and temp switch were fine. This led me to think the fan relay was out. There is a pair of relays on the left of the fire wall. I suspect that one of these is what I am looking for, but as I am a C2 guy I really dont have a clue. Thanks for any help you can offer.

tblt44

The later C4's have the relays to the left of the radiater.I have 3 on my 95 the top one is thr fan relay with the A/C the other 2 are for each fan

rodj

At what temp ? stock fan doesn't run until 225F+
Which temp switch did you check?
Common for lots of crap to get sucked up into front of C4 radiator restricting low speed air flow
Year model?
RHD? (stuff gets moved all over the place with conversion)

Aussi-66

Hi guys thanks for your answers, yes the car is a right hand drive conversion so stuff could be anywhere, that said it is a very nice conversion some of them are really rough. I have attempted to attach photos of the engine bay and the left side of the fire wall. From the engine bay shot you may be able to see that the car is fitted with only one fan even though the car has AC. The thermoswitch I tested was located towards the top right hand side of the radiator. The relays are located in the bottom left hand corner of the engine bay picture and there is a close up of them in the second photo. The two relays on the common bracket attached to the fire wall have the same number.
Given that the car is a right hand conversion all bets may be off, many thanks for your time and effort.

http://smg.photobucket.com/albums/v6...eenginebay.jpg, http://smg.photobucket.com/albums/v6...hefirewall.jpg

86PACER

The fan relay is the squared one with the 10038311 part number on it. It's a simple relay. Should be 4 terminals. When voltage goes across it's coil (one side voltage from computer, one side ground), the other two terminals pull closed which completes a seperate voltage path to the fan motor to spin it. I've have this relay go bad on me before.

By factory the fan is programed to kick on at about 228 degrees.

AGENT 86

The pair of relays are probably fuel and OD, the relay on inner fender, below those two, is most likely the fan relay.
The switch you tested, is most likely to be the "low coolant level" switch.
The computer controls the fan relay. It gets it's info from the coolant temp sensor at front of intake.
Not sure what year that is, but my 86 has a fan fuse in main panel. It powers primary side of coil. Fan power, should come straight from battery, through fusible link, and then into secondary side of relay.
Could be the fuse or the fusible link, that is stopping fan operation.
Testing the relay terminals, should clear some of the fog.


http://members.shaw.ca/corvette86/Co...%20Control.pdf

Aussi-66

Guys thanks for the excellent information it got me going

gwagg

So what temp does the secondary fan kick on?

WVZR-1

This six year old thread is of no value to you I'd say!

I'd suggest you start a "new thread" mentioning the year and what your issues are. There's much information that is year specific and your question is one that is related to year specific and dependent upon circumstances of the controlled device.

1993C4LT1

236

FOURSPEEDVETTE

236 degrees is the secondary fan turn on point. Good question no matter how old the thread may be though.

WVZR-1

Year matters - the most recent poster mentioned none and your 236° I doubt is correct for all years. Show me maybe.

***I agree that it should certainly be "running" but turn on? Then there's of course the +/- tolerance/variation of the ECT sensor to consider maybe.

FOURSPEEDVETTE

On a 1985 C4, the secondary fan (if you have the heavy duty cooling system option) is designed to kick on at 236 degrees. It is not running until that point. The main fan kicks on at 228 degrees. I am not sure about other years of the C4.

WVZR-1

I believe we all could agree that at 236° AUX or high speed, secondary should be running but the most recent inquired post seems to likely have a later C4 (his avatar) where the fans are PCM/ECM controlled and there's certainly different #'s for most years and various commanded temps etc.

gwagg

Thank you, It's 94 base

WVZR-1

'94 COOLANT FAN CONTROL is in this single post from the FSM

https://www.corvetteforum.com/forums...post1591813543

gwagg

Thank you that is very interesting, man these cars get hot!