A/C may be causing slightly over heat condition.

[98EdBomber]

Recently replaced the thermostat housing because it was leaking. I have driven it for 2 days and no leaks. Thermostat new as well. It will start and run fine in the morning and heat up normally and stay in the "middle" of the temp gauge.

Within the last two days it has been 105* F and this is when the problem occurs.

During the morning commute it was only around 78*F and I had the A/C on HIGH the entire trip just to test it (even though i didnt need the A/C). The commute is about 30 minutes or so. While A/C on HIGH, I had no problem whatsoever the entire trip.

In the late afternoon (4pm) it was 105*F and about 25 minutes into the trip with the A/C on HIGH, the engine temp SLIGHLTY raises just past halfway and the engine idles at around 1200 rpms or so and the idle is definitely a little shaky. Normally at around 750 rpm. Mind you, this only happens when I end up in stop and go traffic or sit at a stop light for a while. The temp will go back down when I start driving again and the idle sometimes goes back down if I drive for a while. Then if the compressor is still on, the problem will come right back. If I drive with the compressor OFF, it never overheats or raises idle. Purrs like a kitten actually.

Also, in the morning the rpm doesnt increase much with the A/C on High. I can hear the engine rumble a little when it turns on and it adjusts the idle and settles down a bit. But the idle definitely is a little rough when the A/C is ON. With the compressor OFF, the idle is pretty smooth.

When the compressor is engaged, the plate clicks but it sounds like the bearing is going out. Makes a dull grinding sound. Just had the A/C freon recharged last month with exactly 30 oz. This issue has all of a sudden started when it got over 100*F.

Could a bad A/C bearing be causing this odd over heat/high idle condition or is it something else in the cooling system?

Hopefully someone has had this issue before. Thanks for all the help if you can.

T-

EDIT: I have an OBDII scan tool that has live data. If I hook it up while this condition is occurring, is there any information that could help point to the problem?

 

[koda2000]

my thoughts... any additional load on an engine (especially when it's very hot outside) will cause the engine temp to increase. the a/c compressor puts an extra load on the engine, that's why the PCM increases the idle speed when the compressor engages. you say you had the a/c system recharged and it took 30 oz of refrigerant. was this done by a qualified a/c tech using gauges? if the system was overcharged it might put an extra load on the engine, although i would think the HIGH pressure switch would cause the clutch to disengage. you also say it starts running hot while stopped. this could be a cooling fan clutch issue. if the fan clutch is worn out it wont cool the rad and a/c condenser while stopped. also check to make sure the a/c condenser isn't clogged with bugs and/or leaves. as far as the rough idle, that could be a tune up issue which is only showing up when the load is on the engine. if the a/c clutch bearing is going it could be causing extra resistance but only while the clutch disengaged. i changed an a/c clutch on one of my 2000 5.0 Mountaineers last year (the hub rattled while disengaged) it includes the new bearing. it was pretty easy to change the clutch, although i had to go back and readjust the air-gap after a couple of days.

you might want to have the refrigerant pressure checked when it's hot out. if you want to change the a/c clutch i can give you the benefit of my experience doing this.

 

[98EdBomber]

Ive had this vehicle since it was new and Ive ran the AC every summer and never had this overheat issue.

I had the AC charged by a qualified shop with gauges and they weighed the freon.

The idle rpm doesnt normally increase when clutch engages. It will normaly stay around 750 rpm with ac on high. Only until I drive for about a half hour in the heat.

Thought it was the fan clutch as well so i just replaced it the other day. And besides I think it needed to be replaced anyways because it was starting to hum pretty bad. Now the hum is gone. Same overheat problem occurred after replacement. The mechanical fan comes on with the AC.

I only hear the grinding AC compressor when it is engaged. It doesnt grind when the AC is OFF. The system is leak free and does blow cold air in fact.

Condenser fins are not blocked with debri or deformed.

I think its maybe the radiator or the AC condenser is blocked internally somehow and heating up and the residual heat is affecting the radiator but thats just a guess. Its a stock radiator from when it was new in 1998 so I guess its due for replacement anyways. I ordered a new rad tonight.

 

[my98nnj]

Definitely check the fan clutch as mentioned above.
When you replaced the t-stat, was the system drained send refilled with new coolant? And was the coolant mixed correctly (50/50) or was premix used?

Reason I ask, straight coolant isn't very good at transferring heat.

 

[98EdBomber]

Definitely check the fan clutch as mentioned above.
When you replaced the t-stat, was the system drained send refilled with new coolant? And was the coolant mixed correctly (50/50) or was premix used?

Reason I ask, straight coolant isn't very good at transferring heat.

Yes. Replaced fan clutch two days ago. Yes and yes with distilled water.

 

[Sedition]

OK sometimes with a new fan clutch you have to unhook the bi-metal spring and exercise the engaging mechanism back and forward from limit to limit about 50 times to free it up enough so the spring will be able to turn it on its own with temperature change.

I have a thread about this somewhere, I'll have to try and find it.

Also, when your Ex is revving at 1200rpm, that's the engine trying to cool its self down with the fan. If you cant hear the fan roaring while your revving at 1200rpm (even with the window up) then that's a classic sign of an inoperable fan clutch. It's easy to fix, just a pain to take off and put back on.

 

[Turdle]

Could also be an issue with contamination build up in the radiator, or, a leaky radiator cap.

 

[Sedition]

OK, here's my thread about it.

New Fan Clutch Not Working

 

[98EdBomber]

Could also be an issue with contamination build up in the radiator, or, a leaky radiator cap.

Hmmm. I agree about the radiator. The rad cap...so im assuming when it gets extremely hot the cap would open too easily if its faulty? Or maybe i dont know exactly how the rad cap is supposed to deal with extreme hot temps.

Oh and also I have not noticed the overflow tank losing any coolant since i repaired the thermo housing. So I doubt it is boiling over.

 

[98EdBomber]

OK, here's my thread about it.

New Fan Clutch Not Working

It engages when i open the hood after getting home. IAT was about 118* that was read on the scan tool. So I assume its working properly.

 

[98EdBomber]

OK sometimes with a new fan clutch you have to unhook the bi-metal spring and exercise the engaging mechanism back and forward from limit to limit about 50 times to free it up enough so the spring will be able to turn it on its own with temperature change.

I have a thread about this somewhere, I'll have to try and find it.

Also, when your Ex is revving at 1200rpm, that's the engine trying to cool its self down with the fan. If you cant hear the fan roaring while your revving at 1200rpm (even with the window up) then that's a classic sign of an inoperable fan clutch. It's easy to fix, just a pain to take off and put back on.

If I pull over and open the hood when its overheating and revving high, what should I look for? Is it functional as long as its spinning? Id think if it failed it wouldnt spin at all?

 

[Sedition]

What your looking for, or rather listening for, is noise. When the fan clutch engages you will hear it ROAR. If you think you 'might' hear it roaring then its not roaring, this is one noisy fan when it gets going.

When the fan clutch is in the disengaged position it will still spin and spin quite fast. but it won't make that distinctive "ROARing" noise it makes when cooling the radiator.

 

[Sedition]

It engages when i open the hood after getting home. IAT was about 118* that was read on the scan tool. So I assume its working properly.

It probably won't engage until the coolant sensor temp hits 190*F or above.

The IAT is irrelevant when it comes to the functioning of the cooling system.

This is how the cooling system works in a nut shell:
The thermostat opens at 190*F and pushes that hot water into the radiator. The radiator then becomes hot and the small amount of air pulled through the radiator by the fan, in the disengaged mode, then heats the spring on the fan clutch. This engages the fan clutch and pulls massive amounts of air through the radiator core, causing a load roaring sound in the process.

If your still unsure then let me know and I will attempt to record my fan Roaring with my phone and post it on here so you will know exactly what to listen for.

It's the middle of winter and 9:30 at night here in Australia but I can guarantee you that my cooling fan will still Roar regardless.

 

[Sedition]

Healthy fan noise in cold weather 45*F

I thought I'd make this video anyway for the good of this forum.

So I warmed up my Explorer and found a quiet spot to put Park it and rev the engine @ 2500 rpm for 2 mins. For the entire video the engine was steady at 2500 rpm it is just the fan speed that's changing.

For the first 10 seconds or so the fan is quiet then it begins to kick in. Now, because it's so cold here, the fan only kicks in slightly but you can still hear it roaring in the back ground. On two occasions the fan clutch grabs fully but only for a second or so and you can really hear it ROAR! This happens in the middle of the video (around 1min 8sec) and again towards the end of the video (around 1min 55sec) then it cuts right out again.

https://www.youtube.com/watch?v=lw7JwaGsvSk

I apologize for the crappy sound quality but it is all I have available to me at this time.

 

[98EdBomber]

I thought I'd make this video anyway for the good of this forum.

So I warmed up my Explorer and found a quiet spot to put Park it and rev the engine @ 2500 rpm for 2 mins. For the entire video the engine was steady at 2500 rpm it is just the fan speed that's changing.

For the first 10 seconds or so the fan is quiet then it begins to kick in. Now, because it's so cold here, the fan only kicks in slightly but you can still hear it roaring in the back ground. On two occasions the fan clutch grabs fully but only for a second or so and you can really hear it ROAR! This happens in the middle of the video (around 1min 8sec) and again towards the end of the video (around 1min 55sec) then it cuts right out again.

https://www.youtube.com/watch?v=lw7JwaGsvSk

I apologize for the crappy sound quality but it is all I have available to me at this time.

Ok wow I can definitely hear it kick in at midway there. That was loud.

I just replaced mine with a new fan clutch and have not really listened to it.

But I did hook up a scan tool on the way home today. It was 105*F ambient temps today. Im sure thats nothing for you Aussies!



Drive time = about 45 minutes. Little stop and go and mostly highway.

On initial start up it climbed to 192* and stayed steady so I assumed the t-stat opened. Now this was with the AC OFF. During stop and go it climbed to about 195-199*F ECT. So I turned the heater on full blast and sure enough even in stop and go traffic is ran smoothly at 192 -195 without a hiccup.

NOW, I turned the AC ON HIGH. On highway it climbed to about 207*F or so and stayed steady until about 20 minutes later when i ended up in stop and go traffic and the highest it peaked was a whopping 221*F but didnt go beyond that. Again I got near home and turned off the AC and it didnt quite get back down to 192*F but stayed around 201*F or so. But Im assuming if I continued to drive it would repeat the same numbers. So I ended the test there.

I think the fan clutch is engaging because when AC is OFF, it will stay at 195* or so without a problem. Even in stop and go traffic.

Not sure what this means but thats all I have for now.

 

[JimMadsen]

Just for giggles, have you tried burping the coolant again? I recently had spikes in my sedan in stop and go. This was months after I did a water pump change. I burped the system, did not see any bubbles, but could have missed it. I used a no spill funnel from napa which allows easy burping. But since I did that, no temp spikes. My coolant in the tank and the radiator was perfect before and after burping. Whatever air I had was trapped somewhere weird. It took me weeks to figure it out because I kept popping the top off and level was at the top.

I assume you are getting the same thing, stopped in traffic or going very slow and the needle starts rising past your comfort zone. Then give it some speed once out of traffic and comes right back down.

Just my opposing opinion to the clutch fan chorus.

 

[98EdBomber]

Just for giggles, have you tried burping the coolant again? I recently had spikes in my sedan in stop and go. This was months after I did a water pump change. I burped the system, did not see any bubbles, but could have missed it. I used a no spill funnel from napa which allows easy burping. But since I did that, no temp spikes. My coolant in the tank and the radiator was perfect before and after burping. Whatever air I had was trapped somewhere weird. It took me weeks to figure it out because I kept popping the top off and level was at the top.

I assume you are getting the same thing, stopped in traffic or going very slow and the needle starts rising past your comfort zone. Then give it some speed once out of traffic and comes right back down.

Just my opposing opinion to the clutch fan chorus.

Well I did have a minor leak in the thermostat housing and replaced it. Now no leaks. I did burp it over the next few days, but i will do it again tomorrow morning until it heats up with the heater on high and see what happens. Thanks for your advice.

 

[koda2000]

Well I did have a minor leak in the thermostat housing and replaced it. Now no leaks. I did burp it over the next few days, but i will do it again tomorrow morning until it heats up with the heater on high and see what happens. Thanks for your advice.

one burp should be sufficient. you burp it to get the air out of the water pump so that it will circulate the coolant. once you get it to circulate it will expel any remaining air into the overflow tank all by itself. you also might want to verify that your temp gauge is registering correctly. with the rad cap off, stick a meat thermometer into the coolant and run the engine. the coolant should be around 190-200 degrees F and as water doesn't boil until 212, running with the cap off shouldn't be a problem while you check. if you have one of those laser temp checkers, even easier.

 

[98EdBomber]

one burp should be sufficient. you burp it to get the air out of the water pump so that it will circulate the coolant. once you get it to circulate it will expel any remaining air into the overflow tank all by itself. you also might want to verify that your temp gauge is registering correctly. with the rad cap off, stick a meat thermometer into the coolant and run the engine. the coolant should be around 190-200 degrees F and as water doesn't boil until 212, running with the cap off shouldn't be a problem while you check. if you have one of those laser temp checkers, even easier.

I have an OBDII scan tool that reads coolant temp (ECT). Im assuming its accurate. With the AC OFF I get 192 usually and it stays pretty consistent with normal driving, even in stop and go. I installed a 192*F thermostat last week.

When the AC is ON is when the temps jump. But usually only when its 100+ outside and Im in stop and go traffic. I didnt have time to bleed today as I was busy all day. I might be able to do it tomorrow. I have AC compressor and drier that needs to be installed hopefully by this week when I get time.

And I ordered a radiator last week. A local mechanic thinks it may help with a new one. Its the original rad so thats almost 16 years. It probably would be a good idea to change it anyways as I plan on keeping the truck until the wheels fall off. Hopefully these things will help. Thanks for your input.

 

[JimMadsen]

And I ordered a radiator last week.

Which one did you order? Have to get one myself this week for my 00 Mounty v8 5.0.