I may not be calling it the right thing, Im not sure I mean the pcm.

Basically testing what they are in these videos:



Unless Im looking at the wrong thing, its been raining all day here so I havent been able to do much with it yet or really get in there. After I take my son to boyscouts Im going to pull it in the Garage and work on it tonight. Ill try to get some pictures of the parts Im talking about.

The part they are testing in the videos runs to a "relay" if Im calling it correctly that is behind the left headlamp. I have followed the connector and the wires from the fan to the box behind the left head lamp.

If you could provide me with the technical name for that box so i can call it correctly I would appreciate it. I believe it may be the cooling fan relay or the radiator fan relay. If im way off base here please feel free to educate me, I just havent seen anywhere else call it the PCM which is why I may be getting confused. I like to learn and know for the future.

 

It's the relay. The point of jumping it is to take it out of the circuit. If the fans then work, you know that the fan motors and fuse(s) are good. You've already tested the motors and the relays with the tests you posted above. The fans worked and the relays did too.
A possible cause of "boiling" is a blown head gasket. Let's rule out everything cheap (like a radiator cap) before we look for big trouble.

 

I flushed the radiator again and got a new radiator cap and it seems to have did the trick!

No more coolant spewing out of the reservoir and the fan cut on all on its own with the car hit the half way mark on the temp gage.

Thanks again to everyone here for all of your help! I love my sebring so Im sure I will be back in the future. I need to tackle the AC Blower Motor on it next

 

Greetings.

We've got the same engine (2001 Sebring convertible 2.7). Same "symptoms" and "fixes" performed.
We've ALSO got a blown head gasket (99.9% certain about that).

HOWEVER, we've been limping along for 2,000 miles. We'll continue to limp unless/until $$$ materialize.

BUT HERE'S THE QUESTION:

Cooling fans are "intermittent." Neighbor guy replaced ENTIRE relay box & wiring harness. (Neighbor guy didn't think about PCM?) Neighbor used "Blue Devil" which worked - for a few weeks- in fixing blown gasket.

It seems very likely (to me) that the PCM isn't acting right.

-OR-

Or what? ... When I remove the low/high cooling fan relays, SOMETIMES it goes to "fail safe" mode, i.e., sometimes the fan(s) come on, other times, NOT. Turning on the AC (with the car cold, right?) SHOULD activate cooling fan, but does NOT. (NOTE: Air bleed assembly was also recently replaced - so the sender on it is not suspected.)

THEREFORE: If (IF) wiring is correct, PCM is B-A-D?? PCM costs $100, but I'm STRONGLY inclined to replace it myself, so AT LEAST the cooling fans work!!

SO ... is it 100% true that if wiring AND relays are both good, then "non-standard" functioning of fans is CAUSED by bad PCM? By that I mean, will a broken PCM actually "cause" the cooling fans to "act-up"? ... We're assuming the fan wiring/motors are OK. I'm not a mechanic, but when I pulled the high/low speed relay, the fans came on, THE FIRST TIME.
I repeated the fail safe mode test - the next day...then no dice, no fan(s)! Jeez...VERY unpredictable ... which is why I say "cooling fans are intermittent."

One last thing, on the AC-heater "control head/module" blows ONLY on settings 3-4. I don't ever hear any blower motor when set to 1-2. Does that also have anything to do w/ PCM? [You'll love this: she ALSO had the heater-AC control replaced last year.]

Best,
Paul

 

Way back at the beginning of this thread we pointed out that the fans are not supposed to work all the time. They only come on under certain conditions as determined by the powertrain control module (PCM also known as the engine computer). They are SUPPOSED TO BE INTERMITTENT.

"Turning on the AC (with the car cold, right?) SHOULD activate cooling fan, but does NOT." Wrong. Cold engine, A/C on does not activate the fans. You still need certain temperatures and/or certain A/C pressures.

You haven't mentioned any overheating. If it's not overheating, then leave it alone. With all due respect, I don't think your neighbor guy knows what he is doing.

That head gasket isn't going to either fix itself or go away. It can lead to major problems like coolant in the oil, ruined catalytic converter, hydrostatic lock, blown engine.

 

My apologies, symptoms are same, but alot of info to digest. I thought a lot about this, and ASSUMED the A/C would (or should) activate cooling fans. Poor assumption. But I'd almost swear I saw somewhere that the AC turned on activates fans...hence the "?". When hot, "yes" is probably correct? ... Just no AC activation on a cold engine?

Anyway, that's all somewhat superfluous.

Question remains exactly the same: Will a bad PCM disturb/interrupt/perturb the performance of the high/low speed radiator fan relay?

True, blown head gasket disturbs the whole cooling performance by pumping hot gas into coolant, but it will blow again (if fixed w/o ALSO fixing the cooling fan performance). Or, it could get worse before it limps to the stable and back. If she worked at home, she wouldn't have to limp. Hence she'd have $$$. Head bone connected to the neck bone...

The water pump is probably going, (80-90,000?), and the head gasket is gone. That's around $$$ (total) fix, if I'm not mistaken (water pump + head gasket). If she can limp back & forth (for her $100 in parts and my 1/2 hour labor replacing PCM) to work then someday she can afford to hire a cab or buy a used car? She's been limping 1000+ miles, w/ heater turned "on" to help dissipate heat. Why not limp another 1,000? She changed the oil last week, HOPING it won't break down and turn to sludge before...well...crank/rod bearings go? Heck, I dunno, I never got past Auto-II in high school.

Like I say, what she'd be able to afford this week is a new PCM - if it will cause the fans to run properly?

Yes, the neighbor was shooting in the dark a bit, but apparently he seemed real anxious to play Mr. Fix It. I advised against it, but who am I? I'm learning this engine needs very regular (and possibly synthetic) oil changes due to small capacity and tight tubes (the areas the engine oil passes through but can't recall the name). But she bought it w/ 65,000 miles for $6,000, and now that's kinda starting to smart. It was a beautiful convertible until the head gasket went. I'm assuming repairing the head gasket is $$$$? Three digits is ouch, but four digits is...ARGH!

Another way to look at it is this: it has beautiful leather upholstery, both front seats and rear. If I knew somebody that'd buy it for a rebuild, the engine still has POWER. I'm assuming it has sludge/gunk stuck in the heads?

My apologies for the sob story, but this is a sticky wicket.

Best Regards,
Paul

 

PS: it is true that turning on the AC causes the cooling fans to come on when engine is WARM/HOT, or, roughly 170-190F? I'd swear I read that...I could also be mistaken...But the main question is still:

Will a bad PCM cause cooling fans to quit working normally (provided the high/low relays are in good operating condition)?

 

My mistake again, dcotter, sorry 'bout that...yes, you're right, earlier in thread does describe (as you've also done I just realize - oops) AC activating fans intermittently...my reading needs to be more careful...Kind Regards