Keeping Engine Cool With AC (SOLVED UPDATE 7/17/25)

[Yeller]

210 is not hot, if it is not boiling it is not overheating. My 1 classic with AC, 195 tstat. These readings are from the ECU. 185 at highway speeds. climbs to 215 sitting for 2 hours behind a wreck. 102 according to the weather app. AC is still keeping up and the mechanical fan can audibly be heard, when typically, it is silent. Everyone wants their cooling to be at tstat temp, all the time, it's a dream and not reality, the key is does it actually ever overheat, not just be at a higher temperature. If the AC is staying cool, you have enough airflow, however if there is insufficient capacity in the radiator, it may not keep up with the added heat from the condenser, when it does fine with the AC off. Engine tune can have a huge effect on this as well.

 

[Timmy390]

A quick update. I added some VP Racing "cool down" just out of curiosity (similar to water wetter), 2 bottles and it did in fact lower the operating temp under most conditions. I drove the Bronco to Dallas, Oregon with the AC cranked. This drive is mostly back roads driving 45-55 mph, and the temp stayed around 195 consistently, outside temp was 97 degrees.

I did find that the temp crept up while driving in stop and go traffic. Saw temps around 205-210. If I was able to get up to any speed consistently in town, the temp would hover around 200.

I think I am going to try the two small fans mounted to the condenser and see what happens. They aren't horribly expensive, and keeping the condenser cool with enough airflow seems to be the ticket. I will report back in a few days

With a 192 stat this seems VERY normal. I would run it.

I will also mention EFI likes 210ish. Most modern cars run 210 hence the use of 190 plus stats for OEM.

Tim

 

[fishinman78]

210 is not hot, if it is not boiling it is not overheating. My 1 classic with AC, 195 tstat. These readings are from the ECU. 185 at highway speeds. climbs to 215 sitting for 2 hours behind a wreck. 102 according to the weather app. AC is still keeping up and the mechanical fan can audibly be heard, when typically, it is silent. Everyone wants their cooling to be at tstat temp, all the time, it's a dream and not reality, the key is does it actually ever overheat, not just be at a higher temperature. If the AC is staying cool, you have enough airflow, however if there is insufficient capacity in the radiator, it may not keep up with the added heat from the condenser, when it does fine with the AC off. Engine tune can have a huge effect on this as well.

My big concern is it wont stay at 210 or even 215 at extended idle. I shut it off at 221 and climbing. If it would stay at 215 at idle I would be happy

 

[fishinman78]

With a 192 stat this seems VERY normal. I would run it.

I will also mention EFI likes 210ish. Most modern cars run 210 hence the use of 190 plus stats for OEM.

Tim

As long as I can keep the idling to a minimum and not sit in one place too long it seem fine. I would have concern if I ever had to site for more than 5 minutes. It creeps up quickly with extended sitting hence wanting to give the small fans a try, more air flow at idle, and a cooler condenser

 

[Yeller]

I wouldn't be concerned even at 220, but that is me, I get not wanting to damage anything either, and it continuing to climb is an issue.

I just reread this thread, couple of more things to ponder. I see metal explorer fan, which is as good as it gets IF the clutch is working properly, they do wear out and suffer from the same quality control issues as the rest of our "new" parts, so I wouldn't rule that out. The other is the inner fender screens, they do help, our beloved trucks suffer from tight engine compartments and sometimes they need some help getting air out of the engine bay, I also get not being excited about installing them. I'd save it for last as well.

I will share a heating story that freaked me out and caused a lot of heart burn for nothing. I had an engine that I put TBI on, that I had run for a few months carbed until I got the TBI finished up. it never broke 200. I put the TBI on and the first long grade I pulled the temp jumped to 230, this was with a manual gauge, I panicked shut it down and decided to go back down the grade to town. Parts store was closed, so I ran some screws through the clutch to make it direct drive, made sure it was full of coolant and drove it around some to make sure the tstat was working. Went back up the grade, immediately hit 230 again. pushed on to the top, stayed at 230. The summarization was that the TBI leaned out the mixture and adjusted the timing enough to make the engine make more heat. It never boiled and never exceeded 230 but it always made you think. Sometimes we need to push what we feel are the limits before finding what is too far. The hard part is doing that in a controlled environment that doesn't leave us walking or allow us to push too far and damage something.

PS: I did replace the clutch the next day after the parts store opened.

 

[ntsqd]

The way that it was put to me a long time ago is that roughly 1/3 of the energy in the fuel is used to move the vehicle, 1/3 is dumped by the radiator, and 1/3 goes into the engine oil. What does every ~80's or later model Trailer Towing or HD use package include? An engine oil cooler. I'd avoid using the liquid to liquid cooler from an EFI 460, Explorer, or one of the later FSB's because that just puts more load on the radiator. Spend the money on good hoses and fittings and a liquid to air cooler. BAT-Mocal and Setrab would be the two cooler brands that I'd look at. Unless you stumble onto a Harrison at a price that mere mortals can pay. Long, out of Canada, used to be sold by some of the roundy-racer suppliers, and are pretty good too. Engines with good oil coolers on them seem to get more life out of the oil. If you're in country that can get cold you may want to look at including the BAT-Mocal oil t-stat in the cooler system. It by-passes the cooler until the oil reaches 160°F. Can find it on Summit.

The guy two houses down the street bought a used Volvo Class 8 OTR truck to pull his triple axle ginormous toy hauler with. One day he had the hood open checking things, so I had a good look at it. Two things that I noticed; the mechanical fan clutch was air actuated and controlled by the ECU, and the fan shroud was attached to the engine with a rubber bellows seal between it and the radiator. Some things to think on..... Before y'all get jealous, his concrete driveway used to hate that truck, but now has fracturedly accepted it.

 

[Yeller]

using an oil cooler was something we learned doing endurance racing was required, it helped with heat mitigation a lot. If I ran sand more in my Bronco it would have one. I actually have one to install and just never have, that will be version 3.0 LOL .

 

[fishinman78]

The way that it was put to me a long time ago is that roughly 1/3 of the energy in the fuel is used to move the vehicle, 1/3 is dumped by the radiator, and 1/3 goes into the engine oil. What does every ~80's or later model Trailer Towing or HD use package include? An engine oil cooler. I'd avoid using the liquid to liquid cooler from an EFI 460, Explorer, or one of the later FSB's because that just puts more load on the radiator. Spend the money on good hoses and fittings and a liquid to air cooler. BAT-Mocal and Setrab would be the two cooler brands that I'd look at. Unless you stumble onto a Harrison at a price that mere mortals can pay. Long, out of Canada, used to be sold by some of the roundy-racer suppliers, and are pretty good too. Engines with good oil coolers on them seem to get more life out of the oil. If you're in country that can get cold you may want to look at including the BAT-Mocal oil t-stat in the cooler system. It by-passes the cooler until the oil reaches 160°F. Can find it on Summit.

The guy two houses down the street bought a used Volvo Class 8 OTR truck to pull his triple axle ginormous toy hauler with. One day he had the hood open checking things, so I had a good look at it. Two things that I noticed; the mechanical fan clutch was air actuated and controlled by the ECU, and the fan shroud was attached to the engine with a rubber bellows seal between it and the radiator. Some things to think on..... Before y'all get jealous, his concrete driveway used to hate that truck, but now has fracturedly accepted it.

Are you talking about something with a fan mounted remotely or something that would mount below the grill by the crossmember?? I'm running out of room in front of the radiator with the condenser there.

 

[ntsqd]

Put it anywhere it will fit if you can get airflow thru it. I've seen some ATF coolers laid flat under the mech fan. No idea how well that works, but if it does then that's an option.
A separate electric fan is another option. I'd put a electric fan on a thermo-switch that has it's sensing nose in the oil itself. I'd choose one with an on temp in the 180°-200¯F range.

 

[pbwcr]

Fishenman 78,

IMO, your biggest issue is a poor choice of fan/clutch.

With great success I went with the Explorer fan and a different clutch

Tons of EB links using explorer setup. It all started with my research done on the Jeep forum. Since I had a TJ and an EB it all came together. 72 EB with Mustang motor and Explorer front dress.

Here are research links to get started. I liked all the research leading to my final choice for the fan/clutch.

http://www.jeepforum.com/forum/f9/tj-radiator-fan-upgrade-info-2000-2006-tj-1237538/index41.html

[The Original] Mechanical Cooling Fan/Clutch Upgrade for 1993-1998 Jeep ZJ V8 | Jeep Enthusiast Forums (jeepforum.com)

Here is the basic ‘How To’ for the Explorer conversion using the correct fan.

https://classicbroncos.com/forums/showthread.php?t=287769

My final choice:

Hayden clutch 2794

Ford 11 blade 18” fan F87A-8600-EA = YA220

Details:

The shroud is important. I redesigned mine to get the proper spacing of the fan. I had a plastic one and used some fiberglass to get it correct. Others used an aluminum shroud one from one of the vendors. If you have heavy-duty motor mounts then the shroud has to be recentered to account for the slight motor lift.

My EB has a trans cooler in front of the stock copper radiator. No trans connection to the radiator. I added a thermostat bypass for that cooler because I live where it gets cold.

 

[73azbronco]

explorer serp, stock explorer steel fan, which means heavy duty clutch, stock explorer water pump, WH 2 inch BL fan shroud stock, fan is inside shroud about 3/4ths of fan depth. Keeps my 347 cool in stop and go traffic immediately after leaving freeway doing 65mph for 2 hours during 110deg day and 7% grade climb to a 7,500ft. Big gulp kept me cool.

Oh, manual nv4500. That probably does help a lot, but if or when I go to a 4r70 or such, I plan to use external mounted cooler with it's own fan and run it through radiator, to help warm it up when cold.

 

[fishinman78]

Fishenman 78,

IMO, your biggest issue is a poor choice of fan/clutch.

With great success I went with the Explorer fan and a different clutch

Tons of EB links using explorer setup. It all started with my research done on the Jeep forum. Since I had a TJ and an EB it all came together. 72 EB with Mustang motor and Explorer front dress.

Here are research links to get started. I liked all the research leading to my final choice for the fan/clutch.

http://www.jeepforum.com/forum/f9/tj-radiator-fan-upgrade-info-2000-2006-tj-1237538/index41.html

[The Original] Mechanical Cooling Fan/Clutch Upgrade for 1993-1998 Jeep ZJ V8 | Jeep Enthusiast Forums (jeepforum.com)

Here is the basic ‘How To’ for the Explorer conversion using the correct fan.

https://classicbroncos.com/forums/showthread.php?t=287769

My final choice:

Hayden clutch 2794

Ford 11 blade 18” fan F87A-8600-EA = YA220

Details:

The shroud is important. I redesigned mine to get the proper spacing of the fan. I had a plastic one and used some fiberglass to get it correct. Others used an aluminum shroud one from one of the vendors. If you have heavy-duty motor mounts then the shroud has to be recentered to account for the slight motor lift.

My EB has a trans cooler in front of the stock copper radiator. No trans connection to the radiator. I added a thermostat bypass for that cooler because I live where it gets cold.

I already have the full explorer serpentine with explorer metal clutch fan. Using the Hayden 2851 (same as 46049) Severe Duty Clutch with this fan and a Ron Davis a full circle aluminum shroud.

I may be wrong but I can't see the explorer plastic fan and clutch pulling much more air than the explorer metal fan and clutch.

Transmission cooler is remote mounted with a derale cooler and fan.

 

[73azbronco]

I already have the full explorer serpentine with explorer metal clutch fan. Using the Hayden 2851 (same as 46049) Severe Duty Clutch with this fan and a Ron Davis a full circle aluminum shroud.

I may be wrong but I can't see the explorer plastic fan and clutch pulling much more air than the explorer metal fan and clutch.

Transmission cooler is remote mounted with a derale cooler and fan.

accurate, metal fan is only one with heavy duty clutch, locking up over 90%, plastic fan has a clutch that locks to only about 80%

 

[fishinman78]

I wanted to circle back to this and give an update as I have solved my issue. The last straw was almost overheating while in a Dairy Queen drive through waiting for an ice cream. The Bronco hit 235 and I had to shut it down and wait for it to cool while eating my ice cream (not a bad way to kill the time I admit)

The explorer fan and clutch setup just weren't working at idle, So I started doing some research.

I came across a newly designed fan by vintage air. It is an 850 Watt PWM fan with integrated shroud that bolts right to the factory style radiator. After reading how it worked, I decided to give it a shot. The fan was non stock and built to order, so I ordered through Summit Racing with the required controller. I got the fan installed earlier this year but had not had a chance to fully test it. It was 99 degrees here yesterday so I thought it would be a perfect time to put it to the test. I cranked the AC to max and hopped on the freeway. I did a quick run up I-5 to get the temps up. I pulled a particularly long grade and exited the freeway at the top of the hill. When I took the exit the temp was at 215. As I begin to roll through town I could hear the fan going like crazy and was pleasantly surprised to see my coolant temps dropping. By the time I got home (about 3 miles from the freeway) my temp was 196. I parked the Bronco in the sun, shut the doors and let it idle. In the past it would have never stayed cool at this point, the temps would have just steadily increased until I had to shut it down. I was shocked to see the temp begin to drop! The fan continued to work away, and finally the temp stabilized at 192 and idled there for several minutes.

I could not be happier with how this fan works. It kept the temperature in check and the AC was cranking and cold the entire time!

Here is a link for anyone interested. The fan wasn't particularly cheap, but worth every penny to me!

https://store-xovjmui41g.mybigcommerce.com/content/280483.pdf

 

[Broncobowsher]

Yep, a really strong electric fan can work. 850 watt, that is big time amperage. Given a nominal 12V rating, thats 70 amps. Watch that charging system.

 

[toddz69]

I wanted to circle back to this and give an update as I have solved my issue. The last straw was almost overheating while in a Dairy Queen drive through waiting for an ice cream. The Bronco hit 235 and I had to shut it down and wait for it to cool while eating my ice cream (not a bad way to kill the time I admit)

The explorer fan and clutch setup just weren't working at idle, So I started doing some research.

I came across a newly designed fan by vintage air. It is an 850 Watt PWM fan with integrated shroud that bolts right to the factory style radiator. After reading how it worked, I decided to give it a shot. The fan was non stock and built to order, so I ordered through Summit Racing with the required controller. I got the fan installed earlier this year but had not had a chance to fully test it. It was 99 degrees here yesterday so I thought it would be a perfect time to put it to the test. I cranked the AC to max and hopped on the freeway. I did a quick run up I-5 to get the temps up. I pulled a particularly long grade and exited the freeway at the top of the hill. When I took the exit the temp was at 215. As I begin to roll through town I could hear the fan going like crazy and was pleasantly surprised to see my coolant temps dropping. By the time I got home (about 3 miles from the freeway) my temp was 196. I parked the Bronco in the sun, shut the doors and let it idle. In the past it would have never stayed cool at this point, the temps would have just steadily increased until I had to shut it down. I was shocked to see the temp begin to drop! The fan continued to work away, and finally the temp stabilized at 192 and idled there for several minutes.

I could not be happier with how this fan works. It kept the temperature in check and the AC was cranking and cold the entire time!

Here is a link for anyone interested. The fan wasn't particularly cheap, but worth every penny to me!

https://store-xovjmui41g.mybigcommerce.com/content/280483.pdf

Glad to hear that you've achieved satisfaction with this setup. Thanks for sharing that info with us - apparently that new item snuck in without any of us seeing it come to market (installation doc says 2022). I'm surprised none of the vendors have picked it up and I never saw any PR for it at SEMA, etc.

Todd Z.

 

[Grey owl]

He

Not sure how much it would help but you could drop the coolant/water to 50/50 mix instead. Water is much better at cooling than antifreeze.

He Is already using 75% water

 

[pbwcr]

Hi Fishinman,
Nice find for the fan
What do you use for the sensor temperature to operate the fan?

 

[73azbronco]

I wonder if this is the same fan used to help cool a jeep JT, the pickup with tow package. It is also rated at 850cfm, and JL guys will use it to add cooling power.

 

[fishinman78]

Hi Fishinman,
Nice find for the fan
What do you use for the sensor temperature to operate the fan?

A vintage air controller which comes with the sensor built in is required. They come in different temperatures based on the thermostat you are using.

https://store-xovjmui41g.mybigcommerce.com/content/113018.pdf