oneclean97z

so heres the situation, my fans run, constantly, even on a cold morning startup. ill start the car and around 5 or so seconds later the high speed fan kicks on, ad stays running! this is a no no b/c 1. i dont want them running out alot faster than they could by being constantly ran, and 2. i notice that when on highway for a lil bit it heats up more than it normally does when these fans are on. now for background info: i installed a 160 thermostat and manual fan switch about 2 years ago. its all been fine since, have even replaced the thermo with another 160 recently. i have always noticed that when going down highway for a lil bit i have to turn the fans off with the switch or else it starts getting hotter. so i have always turned them off and temp goes to where is usually is supposed to be (170 or so even at idle with fans being ON) well now the fans are ALWAYS running all of a sudden. so i thought maybe its something with the switch, so i disconnected the switch alltogether, still are always running even when cold.....weird huh? if anybody has any ideas or thoughts shoot them at me it would be much appreciated

my1994z28

Possibly the temp sensor in the water pump went bad?

RamAir95TA

1.) Is the SES light on? If the light is on, the PCM will automatically command the fans to run.

2.) Do you have scanning software, and how does the car run otherwise? Scan the PCM to see what temp the PCM is seeing via the sensor in the water pump. If it's faulty and always reading on the hot side the fans will stay on.

oneclean97z

the light is on and i believe for egr valve. i will re-scan it tomm at autozone. the car runs fine, a slight weird feeling at idle, which is prob that egr valve. hmmmmm, hopefully this is it. whats weird is the ses light has been on for about a year now, for that egr valve, but fans werent constantly running until but a few days ago. the very slight weird idle has also started within the past few days. ill keep this thread updated as i get it scanned and replace the egr. thanks.

Injuneer

May be a separate problem, but if the coolant temp starts to rise when you are on the freeway, the air dam under the front bumper may be missing.

You've also discovered the problem of continuing to drive with the SES light on for what you apparently already determined is an EGR problem. When a new problem crops up that would turn the SES light on, you have no way of knowing. Good idea to fix the problem when it occurs, and use the SES light the way it was intended. I'd guess you blew the fuse for the AIR pump, but as noted..... just a GUESS.

There are multiple codes on OBD-II for the EGR system.... and not all of them require valve replacement. Get the exact code(s) before you just assume you need to replace the valve.

deerslayinrenek

Just taking a shot here.....have the fans been rewired? Could they be pushing air instead of pulling air? That could be the over heating problem on the highway.......

oneclean97z

thanks for the input. injuneer, the air damn is still there, haven't made it to autozone yet but will get exact code number and go from there. air pump fuse? i will check but out of curiousity how would i of potentially blown it? is it b/c it is part of emission system along with egr? thanks again though.

deerslayinrenek, the fans are not rewired they blow the correct direction (towards engine)

Injuneer

AIR has nothing to do with EGR. Its a separate electric air pump that puts fresh air in the exhaust system on startup, to help the cats heat up faster. After 3 or 4 minutes it shuts off. The pump rusts because of exhaust gas that can leak back into the pump. Once the pump rusts, it gets hard to turn, and the amps required to run the pump increase. Eventually, the amp draw gets high enough to blow the fuse. There was a recall on 95-97 AIR pumps, because of the rust problem, and the wiring being inadequate.

Jimbosucks

in my 1994 Chevy Camaro Z28 LT1 the cooling fans are constantly running until the car shuts off how do I fix this problem to where it runs like the factory set it and where is the SES

Injuneer

SES = “SERVICE ENGINE SOON”. Those words are to the left of the tachometer, and directly above the voltage gauge and the oil pressure gauge. Those words light up for two reasons:

• - to indicate the PCM (engine management computer) has detected a problem that could cause damage to the engine or increase emissions.
• - the light should turn on for a few seconds when you turn the key to “run” to show that it is working, then turn off after a few seconds. If this doesn’t happen, the bulb could be burned out, the wiring could be damaged, or someone removed the bulb to cover up a problem.

For more info, there is a diagram of the dash panel on page 92 of the 1994 Camaro Owner's Manual. And the details of the SES light are shown on page 98. If you don’t have the Owner's Manual, you can view it and download it here:

https://my.chevrolet.com/content/dam...aro_owners.pdf

If the light stays on while driving, the PCM needs to be scanned for codes, to see what turned it on. To scan the PCM, you need to attach an OBD-1 scanner to the ALDL connector under the dash, near your right knee. It will give you a list of any codes, which you can look at here:

Courtesy of Shoebox

http://shbox.com/1/Dtcs.htm

There are several codes the can cause the PCM to run the fans constantly. You need the code to determine what needs to be fixed.

pontiacstogo

Fred - you're a star. Seems quite a few people join the forum with no introduction, then dig up an old post with a similar problem and tack on a question. You always provide a helpful response - kudos.