Engine cooling fans operation question

[buickguy62]

Hi,

Learning about my new Reatta--do both cooling fans come on at same time or are they staged? On mine, as the temp increases, only the front (push) fan comes on, runs for a few minutes and shuts off when the water temp decreases. Ambient is fairly low today, about 70 degress F, so if the fans are staged, I wouldn't expect the second fan to cycle. If they are not staged, ie, programmed to run in parallel, then I have an issue.

Thanks in advance

[Guest Mc_Reatta]

Both fans should be running at the same time.

They are wired in series at low speed so they split the battery voltage and run at reduced speed.

When commanded on high speed, they are each wired directly to battery voltage and will run at full speed.

You can check for a relay or fan problem by using diagnostics.

Go into ECM Override mode and turn on the two coolant fan signals and watch what goes on with the fans. (ES07 and 08)

Go to Ronnie's site if you don't know how.

http://reattaowner.com/roj/repair-information/computer-diagnostic-codes/computer-diagnostic-instructions-19881989#pg-1

If both fans run in high speed mode but not low speed mode it's probably the low speed relay. If they both run in low speed mode but one or the other doesn't run in high speed, it's one of the high speed relays. If they don't run in low speed mode and only one runs in high speed mode, the problem is probably the fan that doesn't run.

[buickguy62]

Thanks for the quick reply, I'll check them out.

[buickguy62]

Turns out I have a bad drivers side (pull) fan motor, no continunity thru the motor, I see The Reatta Store (is that Ronnie's site?) has just what I need, so I'll order one from him.

Thanks for all your help.

Tom

[Ronnie]

Hi,

Learning about my new Reatta--do both cooling fans come on at same time or are they staged? On mine, as the temp increases, only the front (push) fan comes on, runs for a few minutes and shuts off when the water temp decreases. Ambient is fairly low today, about 70 degress F, so if the fans are staged, I wouldn't expect the second fan to cycle. If they are not staged, ie, programmed to run in parallel, then I have an issue.

Thanks in advance

What model is your Reatta? Fans on '88 models are wired differently from the later models.

[Ronnie]

Turns out I have a bad drivers side (pull) fan motor, no continunity thru the motor, I see The Reatta Store (is that Ronnie's site?) has just what I need, so I'll order one from him.

Thanks for all your help.

Tom

Thanks! Fan motors are the same for all years.

[Guest Mc_Reatta]

Thanks! Fan motors are the same for all years.

Negatory. Puller fan motor was swapped for a higher output one in 89 on along with the wiring changes.

[Ronnie]

Negatory. Puller fan motor was swapped for a higher output one in 89 on along with the wiring changes.

Are you saying the puller fan motor listed in the Reatta Store won't fit 1988-1991 models?

[buickguy62]

Mine in question is a '90.

Tom

[TexasJohn55]

Does the air conditioner have any control over the cooling fans logic?

[Guest Mc_Reatta]

Ronnie, trying to find the answer to your question sent me on a wild goose chase I really wish I could have avoided. The 89 FSM states that the cooling fans are new for 89 and are a 150 watt puller fan and an 80 watt pusher fan.

The PNs are 22087669 for the pusher fan for all years, while the 88 puller fan is 22074968 and changed to 22081940 for 89-91.

The PN for 88 falls off the face of the earth, so there is no exact replacement for the OEM 88 fan motor. There is no reason to cry about this as the fan from the later cars fits in just fine and results in raising the performance beyond what the stock one gave.

The PN for the later (89-91) puller fan was superceded by PN 22137318.

Now as to confirming the fans in your store. Turned out it comes down to trusting the site on their claim that they meet or exceed OEM specs and they are claimed as replacements for many vehicles.

Going to the manufacturer's sites didn't help as they don't publish the electrical specs for their products. Now the ACDelco site did post crossover info to GM PNs, and the motor in your store did not cross to either of the PNs I found for the Reatta. They did list a cross for the newer PN for our car and it was 15-8498.

Going to RockAuto, they list all your motors as well as several more, including that ACDelco 15-8498. In their listing for it, the say it is a 150 watt motor. No other part site I searched gave any wattage numbers for any of the fan motors that they list as replacements for the Reatta other than this RA entry.

So you pay your money and take your chances. A lot of motors are listed as replacements for all years of the Reatta. I'm pretty sure they will

fit, plug and play fine. But the only one that has a pedigree that traces back to the PN in the later Reattas is the ACDelco 15-8498. But other than a comment found on RockAuto for this one, there is no proof that any of them are 150 watt motors.

Edited October 1, 2013 by Mc_Reatta (see edit history)

[Guest Mc_Reatta]

Does the air conditioner have any control over the cooling fans logic?

Yes, the high side temp sensor readings are used to adjust the fan operation and speeds in addition to the coolant sensor readings. But I think they changed the programming to turn the cooling fans on low any time the AC is on, not just at the temp specified in the FSM.

[Ronnie]

Ronnie, trying to find the answer to your question sent me on a wild goose chase I really wish I could have avoided...

Thanks for taking the time to research the fan motors. I remember going thru something similar when trying to decide which fans I should list in The Reatta Store. I finally concluded that the Four Seasons brand of fans were a good choice when considering price and quality. I also concluded that the Four Seasons fans listed in The Reatta Store should fit all Reatta models. I was not aware of the changes you mentioned but I don't think they would matter as far as backwards comparability.

[Guest Mc_Reatta]

Ronnie, suggest you consider adding the AC Delco 15-8498 puller radiator fan to your store.

http://www.amazon.com/ACDelco-15-8498-Engine-Cooler-Motor/dp/B000C9G1U2/ref=sr_1_1?s=automotive&ie=UTF8&qid=1380643932&sr=1-1&keywords=15-8498

It costs more than the others, but it is the only one with a pedigree that can be traced it back to the original fan motor in the 89-91s.

Also, if you check the weight of the fans, you will see the AC Delco one you list only weighs 1.8 lbs, the 4 Seasons weighs 2.9 lbs, but the 15-8498 weighs 3.7 lbs. That leads me to suspect that it might have higher performance than the others.

That said, I don't think that the ones that you have listed wouldn't work fine in any Reatta, just that there could be a lesser level of performance than the 15-8498 might provide. It's too bad the manufacturers won't provide all the specifications to properly compare these fans.

[Guest Mc_Reatta]

Something you 88 owners might consider if you're concerned about keeping your cars running cooler.

You should have jumped the ballast resistor by now to run the puller fan at high speed all the time, as well as changing thermostats and considered having the fan turn on sooner.

But you might also check if you still have the original puller fan motor installed. (22074968)

You would probably benefit from installing a new higher wattage fan like they upgraded to in 89. I expect they found the first fan to be marginal in hot climates and upgraded it the next year.

Edited October 1, 2013 by Mc_Reatta (see edit history)

[Ronnie]

I have implemented all the suggestions you made and it make a huge difference in engine temperature. I have the jumper installed on the resistor, installed a 160* thermostat and installed a Hayden temperature control that will turn the fans on high when the temp gets to ~190* and then cycles them off again when the temp comes down to ~170* - even when sitting in bumper to bumper traffic on 90-100* days. On the highway the engine runs about 165-175* depending on the outside temperature.

[ssmithmiami]

I am interested in doing what you did in order to bring down the running temperature in my 89. It is fine on the highway, but as soon as I am in stop and go traffic (even at 20MPH) the temperature goes up to 200-205 degrees (and it is worse without the a/c on). I am not confortable with that and would prefer that it should stay between 186-195 degrees.

Where is the resistor onto which you installed the jumper? and how do I find a Hayden temperature control? Does this leave any of the fans running on high all the time? It seems like a relatively easy fix to running too hot.

I spoke with my mechanic about installing a relay, and he said the bad thing about that is that the fans stay on high all the time, which I do not want. I am also uncomfortable about removing the EPROM for reprogramming, the downtime involved, and the possibility of having it lost along the way.

I live in Miami so you can imagine how important it is to have the cooling system be efficient, and how quickly overheating can take place here.

Bottom line is, how can I find out more about this, then let my mechanic know?

[Guest Mc_Reatta]

I solved this problem a long while back with the development of a cheater cable that is plug and play to the car and runs the fans on high speed whenever the car would normally call for either low or high speed fans to come on. If you haven't yet figured it out yet, the low speed operating mode is just about useless, but high speed mode will keep the engine temp to within a few degrees of the thermostat's opening temp even sitting still, idling, with the AC on high. With a stock thermostat my temp peaks at 203 F at those conditions, and with a 185 stat it shows around 192 F then.

The fans will come on high when either the AC is turned on, or when the computer calls for low speed. They will turn off at speeds over 45 - 50 MPH when they are normally turned off as they are not needed due to sufficient air flow.

The 89 - 91s do not have the resistor that the 88s had so the route Ronnie took is unavailable to you in that regard. There are thermostats and relays already built into the car, so there is no need to add more. You can get the fans to run on high when they first are turned just by swapping two wires in a connector under the air cleaner box, but doing this will result in an E026 QDM Fault error code. This is benign, and you could run that way with the benefits of high speed fan operation, and no harm would result from doing so.

In order to prevent the QDM Fault, a bit of electric trickery is needed in addition to swapping those wires hence my calling the fix a cheater cable. It fakes out the ECM so it thinks the low speed fan relay is engaged when in reality it is not and the high speed relays are. I found this the least expensive and most convenient way to address this situation, unless you can self program the EPROM yourself, or need to have that done for other reasons and getting the fan temp modified is a freebie piggyback service.

[harry yarnell]

...and you did this how?

[TexasJohn55]

To ssmithmiami: If I were asked what max temp might be expected with a 195 stat, it would be a little higher than 205. Your system seems to be operating as designed and most folks would be tickled to have theirs run at 205 with ac in traffic. You are worrying about a non-existant problem. IMO.

[dship]

Both my 91 Reatta and my 92 Riviera have 195 thermostats....std for this era L27 3800. I did install new radiators in each when I acquired them and I do perform coolant flushes every 2 years as recommended. With the new radiators I get good coolant flow and the fans go on/off as originally designed. I've never had engine high temps in hot weather/stop n' go with the a/c on. The Riviera has the factory tranny oil cooler. I might consider installing one on the Reatta, though.

[Guest Corvanti]

i would love to see a "tutorial" on the fan(s) cheater wire on ROJ, or someone (Mc?) market one if it was reasonably priced.

"ssmithmiami": when was the last time you had a coolant system "flush"? i did so after i purchased mine 2 years ago and put in a 180 degree thermostat. the highest temp i've seen in the 2 summers since is 204F. i'll probably do another flush before summer when it gets as warm (and humid:() as y'all get there... if i had to do the thermostat again, i'd probably go with a 160 as i did with 2 of my Corvettes and my Studebaker Avanti.

on the other hand, i've seen several threads here saying up to 230F was reasonable for the 3.8L engine. another reason is i'd rather the tranny cooler without going to a add-on. (see a recent thread).

[TexasJohn55]

IMO, If the fans are working properly and stat has been changed but it overheats in traffic, buy a new radiator and be done with it! They are not that expensive and can be bought at local auto parts stores.

[Machiner 55]

IMO, If the fans are working properly and stat has been changed but it overheats in traffic, buy a new radiator and be done with it! They are not that expensive and can be bought at local auto parts stores.

I second that.

John F.

[Ronnie]

If you have a clogged radiator I agree that it should be changed, but ssmithmiami was asking how to cool his engine down from 205*. A new radiator won't make the engine run cooler than 205*, even if the fans are working properly, if you are stopped in traffic. GM designed the engine to run hot. The high speed fan, even when working properly, doesn't turn on until the temperature reaches about 230*. So if you are sitting in traffic the temperature is going to climb until the temperature gets high enough to make the fans run at high speed.

Changing to a 160-180* thermostat should be the first step but making modifications that make the fans turn on at a lower temperature is key to a cooler running engine. Mc_Reatta's modification is probably the best way to go if you don't want to have the computer chip reprogrammed. I added a Hayden fan control system to my car to make the fans run in high speed at ~190* and then cut off when the temperature drops to ~170*. It works well (with a 160* thermostat) but is much harder to install than what Mc_ is talking about.

[Guest Mc_Reatta]

Also need to consider other issues that come along with letting the engine and underhood temps to get well over 200 F

With no airflow over the condenser, the efficiency of the AC goes way down and the vent temp rises significantly so you will be feeling the heat too. Especially if you have converted to R134.

If your brake fluid is on the older side and contains a little too much moisture, and your accumulator is borderline your red light will be coming on and you will start losing power assist, just what you need when you're in stop and go traffic and the outside temp is over 100.

Think of the stress you're putting on those critical temperature sensitive ICMs, CPSs, and MAFs, not to mention all the other electronic and plastic components under the hood.

If you live in areas where you can consider installing a bypass pulley and belt and foregoing fixing your AC cause you don't use it very much, you won't understand what we in the sunbelt are talking about.

My AC is on 90% of the time I'm driving my Reatta year around. If my heater core where to spring a leak, I would not bother to replace it and I could count on one hand the number of times I might question that decision.

[ssmithmiami]

Thanks, everyone, for your input. Should I decide to swap wires under the air cleaner box (I have not lifted it yet to see the wires, probably this weekend) how do I know which wires to swap? How do I find this "plug and play cheater cable" and where do I connect it?

I just read through the service manual's coolant fan control and electrical system description in which it describes how it all works, but it does not give me an idea about which wires should be switched. Maybe I will know more once I look at them.

Thanks for all your advice in advance...