Cooling fan

[Easter]

Cooling fan don't come on when engine gets hot. It blows fuse to air pump kicks check engine light on and raised from by 200. I've checked all power connectors and have power. Changed relay, thermostat, temp sensor, tested fan everything has power and fan works but will not come on. Any ideas would be a big help to a desperate man. Thanks in advance.

 

[bruceb]

Need Make, Model, Engine of vehicle in question. Most cars have 2 temperature sensors .. One for the Gauge and engine computer data input. And another one that just turns on the fans when the sensor gets to its designed temperature. Or on some cars, the computer outputs a signal to the fan relay to tell it to come on. In that case it could be as easy as a bad wire (open or corroded) or since you say the Fuse is blowing out, a wire could be frayed and grounding out the circuit. I would start with a very careful check of the wiring to the fan relay and the fan.

 

[Easter]

Need Make, Model, Engine of vehicle in question. Most cars have 2 temperature sensors .. One for the Gauge and engine computer data input. And another one that just turns on the fans when the sensor gets to its designed temperature. Or on some cars, the computer outputs a signal to the fan relay to tell it to come on. In that case it could be as easy as a bad wire (open or corroded) or since you say the Fuse is blowing out, a wire could be frayed and grounding out the circuit. I would start with a very careful check of the wiring to the fan relay and the fan.

It

 

[Easter]

It is a 95camaro 3.4v6 I've checked all electrical plugs and have power to all.

 

[bruceb]

Your car has a sensor under the upper intake manifold which controls the fan. See this link for more info:
https://camaroforums.com/forum/93-02-v6-tech-14/3-4l-v6-electric-fan-not-kicking-58965/

 

[Easter]

I changed that sensor under intake already. Can't try as cause pump runs but clutch don't lick in and out so I don't know if that method would tell me anything. Right now when I turn as on, fan does not run

 

[Easter]

I meant ac

 

[bruceb]

Does the car overheat ? Normal temp for the fan to come on is 220°F if the AC is not turned on. If the AC is on, the fan should be on all the time. The computer may need to see that the AC has Freon in it before it will turn on the fan in AC mode.

 

[C1]

???????

https://www.justanswer.com/chevy/4ep29-1995-chevy-camero-3-4-v6-its-heating.html

 

[Easter]

Does the car overheat ? Normal temp for the fan to come on is 220°F if the AC is not turned on. If the AC is on, the fan should be on all the time. The computer may need to see that the AC has Freon in it before it will turn on the fan in AC mode.

 

[Easter]

O don't run it long enough to overheat. I ran it for half hour and temp have was quarter way from red line which is way higher than it normally runs so I shut it down at that point in fear of wrapping the heads. I didn't have this problem when I put it up for winter but when I go to get it out this spring it's doing this. Thanks for the prints. I'll try to make heads or tails out of it. Looks confusing. I'm not good with electrical. Thanks...

 

[Easter]

Ok, my relay numbers don't match up to drawing. It says use jumper wire on 1 and 4 and fan should run. I jumped 1 and 3 and fan ran great. So it says bad relay or bad connection at relay. I just put new relay in. How do I check connection at relay. Thanks.

 

[bruceb]

The prints came from camaroforum.com .. the post it is from is in my response. The rest is just a very simple flow chart. Start at the top and depending on the result, it tells you what to check next .. Worst case you may need an auto tech who specializes in the electrical wiring of cars.

 

[bruceb]

You would use a Digital Multimeter to check or voltages.. If your relay does not match the diagram, it is probably the wrong relay. Perhaps it was switch with another one to isolate another problem. Pins 01 & 04 take the +12V and send it the fan (they are the Normally Open relay contacts) Pins 02 & 05 are the Relay Coil which the computer or sensor tells to operate and close the contacts

 

[Easter]

It says I have bad relay or bad relay connection. So I went and bought another relay and cleaned contacts. Still nothing. So I took fuse box off to inspect wired underneath. The power wire going to that relay had insulation off to bare wire in one little spot. Taped it up. Still don't work. Followed wires thru harness and saw nothing else wrong. Every time it gets to point where fan should be kicking in, check engine light comes on instead. Bout to pull my hair out.lol...

 

[bruceb]

Recheck all the fuses. And just because you found 1 wire with bad insulation, does not mean that is the only problem. Perhaps that wire now has an OPEN CIRCUIT between where the insulation was bad and where ever it is coming from or going to. You need to trace it out to find it.

 

[boomerang]

Why is he not being asked for the codes associated with the CEL? I'm also wondering why no concern for him stating in his first post that a fuse related to the air pump blows?

In this car the ECM controls the operation of the fan but there is no feedback on whether the fan comes on or not. The code(s) being set are not fan related and are key to this repair. IMO...

To the OP: What work if any was performed prior to this problem? Is the fuse that blows dedicated solely to the air pump or are other items fed from it? Your owners manual may give you this information or the cover over the fuse block may.

bruceb, it appears you have the manual in your possession. What circuits are fed from that fuse?

 

[bruceb]

I do not have the manual -- I got those schematics from a post at the camaroforums.com which I linked to above.
I usually try to make sure I tell where the info comes from if someone else posted it.

This site has the manual .. either create an account or use Facebook for a 30 day trial.
https://www.scribd.com/doc/309745342/1995-Chevrolet-Camaro-Pontiac-Firebird-Service-Manual-Volume-1

 

[Easter]

Recheck all the fuses. And just because you found 1 wire with bad insulation, does not mean that is the only problem. Perhaps that wire now has an OPEN CIRCUIT between where the insulation was bad and where ever it is coming from or going to. You need to trace it out to find it.

Thank you. I'll try that

 

[Easter]

Well bruce, I want to thank you for all your help. I finally got cooling fan working. I ended up finding 3 open circuits and a disconnected vacuum line. The one open was on plug going to computer. Thanks so much for your help. Your awesome.

 

[bruceb]

Glad you fixed it without the help of a $125 per hour mechanic, who would have probably spent about 2-3 hours on it.