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Not a smart way of checking my fan relays...please HELP!!!
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Ed007
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Nov 13, 2008, 4:38 PM
Post #1 of 10
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Not a smart way of checking my fan relays...please HELP!!!
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Hello,
I have a Chevy Lumina 1997, 3.1 with 145,000mils.
I have been having trouble with my Lumina heating up for a while now. About a month ago I changed the thermostat and flushed the cooling system. That helped for a while, but eventually it started heating up again. I realized that the cooling fan would not come on till the heating gage was all they way on RED. So I came to the conclusion that for some reason the fan would not cool the engine, until dangerously HOT. Today I tried to check the relays to see if i can find the problem. I checked (Fan Cont #1) by removing the relay and creating a connection by placing 2 (V) shaped metal wires and both fans started working. I repeated the process on (Fan Cont # 2), but unlike the first time there was a spark and when i tried to start the car and it would not start. I realize i must have caused an electrical short some where, but i'm not sure where to start. Please help .!!!!
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way2old
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/ Moderator
Nov 13, 2008, 4:50 PM
Post #2 of 10
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Re: Not a smart way of checking my fan relays...please HELP!!!
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Check all your fuses first.
Being way2old is why I need help from younger minds
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Loren Champlain Sr
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Nov 13, 2008, 4:56 PM
Post #3 of 10
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Re: Not a smart way of checking my fan relays...please HELP!!!
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1st, If the fan comes on when "It's dangerously hot", that tells me that the cooling fan motor and the relay is okay.
I'd check the coolant fan switch. Some, are PCM controlled, but have a switch that commands the fan to turn on at a specific value, even if PCM controlled. Many coolant fans don't come on until 234F! Hopefully, you've just blown a fuse or a relay. Most GM relays are interchangable. You could take the A/C relay and plug it into the fuel pump relay socket, ect. But, I'd check the fuses, first. You may have an electrical distrubution box under the hood and additional fuses under the dash. As you've probably learned, it's not a good idea to "jump" across terminals.
Good luck.
Loren
SW Washington
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Ed007
New User
Nov 13, 2008, 6:25 PM
Post #4 of 10
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Re: Not a smart way of checking my fan relays...please HELP!!!
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Thank you very much for responding to my question/SOS !!
I checked the fuses and found a blown one . I replaced it and car starts with no problems. But I still have the problem of cooling fan not starting till gage on RED and HOT warning light comes on..then the gage slowly starts coming back down to middle area. I'm very interested to learn more about “Coolant fan switch and PCM” you wrote about. Now I'm still a novice when it comes to fixing my own car, but I'm trying and very motivated to learn and my wallet appreciates it too. Can you please elaborate on PCM and Coolant fan Switch or maybe you can directed my to a website. I very much appreciate you help and advice and I'll make sure to pay it forward .
Thanks again !!
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way2old
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Nov 13, 2008, 6:34 PM
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Re: Not a smart way of checking my fan relays...please HELP!!!
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Another thing to consider is if the gauge is reading right. You need to confirm the gauge is correct before you go much farther. See if you can get your hands on an infrared thermometer and check engine temperature against what the gauge is reading. As noted above, the fans come on at different temps. Most will come on around the 220 to 225 range. Good luck.
Being way2old is why I need help from younger minds
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Loren Champlain Sr
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Nov 13, 2008, 6:40 PM
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Re: Not a smart way of checking my fan relays...please HELP!!!
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Glad to hear it was just a fuse! The PCM is the computer. The coolant fan switch is usually mounted near the thermostat housing. But, the problem you are describing sounds like a possible sticky thermostat. By the time the coolant fan switch "sees" the problem and turns on the fan, the engine is already HOT. I haven't learned how to post a picture of the coolant fan switch, but Tom G. knows how. Hopefully, he'll see the post and show you what it looks like, but I'd be real suspicious of the thermostat.
Loren
SW Washington
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 13, 2008, 9:25 PM
Post #7 of 10
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Re: Not a smart way of checking my fan relays...please HELP!!!
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Kitty thinks it looks like this one so if this
is wrong it's her fault!
As way2old mentioned testing actual temp with infrafed thermometer would help a lot to verify the actual temp. Check right at thermostat housing when fully warmed up and the temp should be and stay close to the thermostat's rating ~ 195F +/-
Arggh ! Fan will come on later than the t-stat's temp rating. PCM is likely reading ohms from this sucker to make the call. Don't be jumping three wire switches!
This car may also use A/C's HPCO (high pressure cut out) also with three wires to activate fan(s) also thru PCM,
T
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Loren Champlain Sr
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Nov 14, 2008, 4:36 PM
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Re: Not a smart way of checking my fan relays...please HELP!!!
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And, Tom comes through again! I'm impressed! LOL. I just saw an ad last week that you can buy a digital pyrometer for around $20. We paid A LOT more for the Snap-on one! Would be a good investment for DIYers.
btw, I love cats. Kitty looks like a good one! Lots better looking than her Daddy.
Loren
SW Washington
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Ed007
New User
Nov 14, 2008, 7:32 PM
Post #9 of 10
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Re: Not a smart way of checking my fan relays...please HELP!!!
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Hello all,
First let me just say thank you all for your help I really appreciate it. Okay, Way2old I changed the engine oil today and I saw that the oil was darker than usual and what little i saw of the inside of the engine when i moved the cap was brownish and dried up oil on the bottom of the cap. So i really do think that the car is getting hot..what i mean is that the gage is giving me the write temp reading (what do you think?). Unfortunately i need the car for work so i still have to drive it, I'm just extra careful with it. Landdchamploren, I changed to thermostat a few months back and whata tough job that was  ...its in a really tight spot. To say the the truth the thermostat has been in my mind lately. I bought it at Auto-Zone (i should have gotten it from Chevy dealer) and I'm thinking that it might open at different temp. than the original one (btw, I remember testing the original one and it opened fine) can that be putting the whole cooling system out of wack? I was thinking of going back to AutoZone and see if its on file what kind it was that i bought and research it. I wana replace the coolant fan switch next and see where that takes me.....Tom G. please forward my regards to Kitty for providing a pic of what it looks like.
This morning before going to work, I repeated the process of manually turning on the engine cooling fans (by crossing the first relay terminal, not the 2nd one that caused the fuse blow out) to keep the engine cool till i got to work (30miles from home). I know what you are thinking, but i'm worried the car might not be able to take this over heating for much longer. So..about half way to work I see the gage is slowly moving to the right where the RED is. When it reached the RED, I pulled in to a gas station, but before I could put the car in park the gage started going back to the left....I started driving again and about 5 miles from work it started pulling toward RED, I keep on driving Warning HOT light comes on for about 3 seconds and goes away and i'm still driving...gage starts pulling back all the way left (cool, it goes back a whole 3 quarters) just when I reach the parking lot and almost the same story on the way back to home.
I just thought I'd mention this and hopefully it will help in diagnosing this irritating issue.
Thanks again for all your help!!!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 14, 2008, 9:35 PM
Post #10 of 10
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Re: Not a smart way of checking my fan relays...please HELP!!!
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More suggestions/thoughts/question:
Is the radiator fan working yet and can it show HOT when it's on? If it can read normal when it's on then if you can't figure it out right away then make up a fused jumper wire direct to unplugged fan to force to stay on all the time if you must use the car for now. Run heater (better yet 'defroster') full blast and open windows if too hot for you too can both help AND you should feel the air temp comparative to gauge for a guess on gauge accuracy. When boiling hot the heater will quit - know that! Defrost request MAY force radiator fan to run - not sure for this car.
Is this truly full of coolant and staying that way? If no cap on radiator, when cold just squeeze upper rad hose - no bubble to recovery tank should be seen coming up - if so there's urgent need to find out - head gaskets can do that - sorry for the lousy possiblility but you need to know.
Oil sluge from heat: Maybe. Take a look if you can see thru fill cap as a better indicator. Clean cap and look for recurrance. Synthetic oils tolerate heat tons better than conventionals but not a cover for a problem.
I just think the gauge is telling the truth. Low coolant level could cause it to be late or erratic. Radiator could be inadequate, t-stat might be bad but it's rare with the symptoms so far to me.
Note: Cooling fan(s) really aren't necessary when moving along steadily at speeds over 35-40mph or so if air dams and shrouding is intact. Is radiator clean enough - leaves, bugs etc?
Other: Belt properly tight to turn water pump? Kinda must be or other probs would be happening. Water pumps are usually a cake walk on the 3.1s. Never heard of one yet not pumping but makes me wonder. Has been reported that some can corrode impellers causes low flow at lower rpms at first if so.
Kitty say "Hi" - Can you tell her owner isn't wrapped too tight?
T
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