For the past year and 1/2 Ive been running with my A/C on to keep the fan on... Ive gone thru 1 fan already and figured its time to fix the fan issue already. This is a list of things ive replaced to get the stock fan to work normal and is still not working unless I have a/c or heat ON.

1. Temp Sender
2. Fan switch between cylinders 8-6
3. Fan Switch Connecter
4. Fan Motor
5. Fan Relay on passanger side

STILL ONLY WORKS WITH A/C and HEAT ON WTF!!??

 

I may have found something... I tried to trace that single green wire on the Fan Switch and believe I discoved it goes to the outher side of the engine to another similar Switch screwed into the block located between the first two spark plugs... the switch seems similar except it has a nipple on the end and the single green wire has a connector that slides onto it...any idea what this sensor or switch is????.... I have a 305 TBI single fan.

 

I think I found IT!!...http://tpiparts.net/inc/sdetail/10956/783 I will replace it and see how it goes keep you posted!!

 

ok wait a minute. the sender that is on the drivers side is for the gauge in the dash.

the one on the pass side between the back plugs is for the fan.

unplug the one on the drivers side and see if the gauge quits working.

 

I actually think the one on the driver side is not for the gauge... the one for the gauge is atop the manifold... I think the one on the driverside is actually for the ECM

 

the one for the ecm is in the intake and has 2 wires going to it.

the one for the gauge is a single wire and it is in the drivers head.

the one for the fan is in the pass head towards the back and is also a single wire.

 

http://austinthirdgen.org/mkportal/m...ine_wiring.gif

 

http://www.austinthirdgen.org/mkport...uges_part1.gif

 

I was wrong... the Driver side sensor was the gauge sensor....what the hell is the coolant sensor on the manifold then??

 

I see your Schematic... where does the A/C control head and fan switch meet?

 

the a/c switch, fan temp switch, and control head switch all go to the fan relay on the same wire. dark green and white. take the dark green and white wire on the switch on the pass side and ground it. see if the fan comes on. if so the switch is bad. if not the wiring in between there is bad.

 

Then I should be able to do a continuity check between that Green/White wire on the relay and the wire to the Fan Switch correct? I removed the relay and the terminal inside looks like it had been burnt on the connector. I should be able to continuity check before and after the connecter to make sure the connector is good?

 

that is correct.

 

OK heres what ive done, I tried to ground that single fan switch by itself...notthing...checked continuity between that fan switch wire and the green/white terminal on the relay it had good continuity...bought a new relay and hooked it back up the the fan switch..notthing... tried to ground that wire again...notthing.. the problem is something else.

 

where is that generator thing I see on the schematics?...it seems far fetch to me that could be the issue?

 

NVM im an idiot that the altinator right?

 

I do not kno what else I can check. any imput?

 

Ground the lead at the relay and the fan should come on (with ignition in 'run'). Continuity check between that wire and the connector at the pass side head. If that's good make sure no one's installed teflon tape on the threads for the sender. It relies on contact to the head for a path to ground.

These switches seldom go bad but their relatively high turn-on temps often prompt premature replacement. Take it out and check it's continuity between the wire connector and the body of the switch while you heat it on the stove (in water). It should switch on around ~210 and off ~190.

 

if it is a factory switch it is suppose to come on at around 238*.

 

I double checked, I found a better ground and the fan kicked onwith the single wire. Its a new fan switch from NAPA... not sure if it has the stock rating or not... I let the temp run to about 245 and turned it off before it goes into red...no fan still...I guess it could be a faulty switch, the connector they sold me likes like it should be it but it slides on and off fairly easy The NAPA part number for that pigtail is S-550. I will try another Fan switch I suppose.

 

if you put on sealant on the threads it will not ground. it needs to be screwed in the head without tape or anything.

and do you have a way to check the temp besides the gauge in the dash.

 

yea its all Brass No anything on it. Its gotta be a faulty switch, theres no outher way.

 

yep if grounding that wire for it got the fan to come on then that system is good. do you have the stock thermostat in it?? if you want to go cooler you can get a different switch like a hypertec switch and a cooler thermo.

 

I have a 180* stat in there right now, I will look into that Fan Switch.. 236* seems a little hot for the fan to start working imo. Thanks I appreciate the help. I will keep ya posted after I get the new switch and install it.

 

yes sir to put in a 180 therm and rely on a 230 something fan turn on isnt going to help it any.

 

hypertech 4028 is the switch you need for the thermo you have.

 

Awesome thank you, I just ordered my 4028, cant wait to bolt it in and see what shes got.

 

good deal man. hope it works out for you.

this is the main reason i went to a flexalite fan controller.

 

I contiplated going that route, But I just wanted the stock setup to work. It will be even better with this switch. I didnt think about it but I should have cleaned the threads on the head with a battery terminal wire brush or something incase of any corrosion in there, it may not be getting a good ground. Maybe it happend for the better.

 

one92rs; you KNOW your smart. I've been doing this since the mid 80s and I can't remember the fan wiring that well. It is great watching the younger guys go through what I went through many years ago. We learned grounding the green wire on the relay to a switch inside and we thought we were genuises. That was about the time hypertech came out with the passenger side cylinder head switch.

 

im not that smart. just been thru these cars a few times. went from tbi to carb and back to tbi. i have also helped a buddy of mine who has put a tbi engine in a variety of cars and trucks. maybe being a mechanic for 25 years has helped a little as well. as far as young??? 43 years young. but i feel a lot older. i like to help people when i can.

 

just curious was this fixed/

 

Not yet, I orderd the part on memorial day weekend, according to the UPS tracker it should be here tomorrow. I wanted to ask you, I put that outher switch on TIGHT with no teflon or anything but it is leaking some collant, Is there anything I can put on the new one that might be conductive?

 

if it is still leaking put on some silicone or what i use is called pipe dope. or liquid thread sealant. but silicone will work also.

 

That stuff will withstand the temp? will it be ok to use on threads or should it be between the threads and the bolt head part?

 

take some silicone and put on the threads. not a whole lot. squeeze the tube and put a big dot on your finger. rub it on the threads near the bottom where it screws in the heads. just make sure the threads are dry.

 

Ok, I will keep ya posted how it goes.

 

The Fan switch was a Success, thank you One92RS. The fan kicks on at about 195* and off at 180*. The fan switch came with a new pig tail plug so I used that one insted of the one from NAPA that seemed to be a sloppy fit with excessive play. For sealant I ended up using some Indian Head Gasket sealant on the back 1/2 of the threads (hopefully it holds a good seal). I hope many with the same issues reads this and does things right the 1st time.

 

Ohhhhh...this must be why my fan isn't turning on now. I wrapped the new one with thread tape before installing!

Disregard.....It wasn't working because I didn't ground it after removing my AC unit. I had to run a wire from one of the harness to the firewall.....works now!