Overheating at idle with AC on.

[DWilliam]

2002 sr5, 145k miles. Let me preface this by saying about 1000 miles ago my head gaskets blew. It was fixed by a reputable shop and then I moved states.

I’ve had check engine codes (p0171, p0300/301) for a while now, I’m assuming it’s my injectors. Haven’t got around to replacing. I can smell fuel though not only after I pump gas, but also slightly after driving. I previously had evap codes that went away when I replaced evap valves, but I’m wondering if my canister is bad too.

Now it overheats while I’m idling with the AC on, even when in the shade. After about 10 minutes the temp gauge will slowly rise all the way to the red before I shut it off. It’s fine if I start driving and get some air moving.

Any ideas? I’m literally about to drive this thing off a cliff.

 

[AuSeeker]

2002 sr5, 145k miles. Let me preface this by saying about 1000 miles ago my head gaskets blew. It was fixed by a reputable shop and then I moved states.

I’ve had check engine codes (p0171, p0300/301) for a while now, I’m assuming it’s my injectors. Haven’t got around to replacing. I can smell fuel though not only after I pump gas, but also slightly after driving. I previously had evap codes that went away when I replaced evap valves, but I’m wondering if my canister is bad too.

Now it overheats while I’m idling with the AC on, even when in the shade. After about 10 minutes the temp gauge will slowly rise all the way to the red before I shut it off. It’s done if I start driving and get some air moving.

Any ideas? I’m literally about to drive this thing off a cliff.

It's possible that when they did the head gasket the thermostat is installed incorrectly with the "jiggle valve" in the wrong position and not allowing all the air to burp out of the system, or either it just may need to be burped to get any remaining air out.

Also check the radiator to see if any debris is blocking air flow, you may need to remove the radiator to get at any debris that is on the AC condenser/front side of it, which is usually where it gets clogged up and not visible.

 

[DWilliam]

It's possible that when they did the head gasket the thermostat is installed incorrectly with the "jiggle valve" in the wrong position and not allowing all the air to burp out of the system, or either it just may need to be burped to get any remaining air out.

Also check the radiator to see if any debris is blocking air flow, you may need to remove the radiator to get at any debris that is on the AC condenser/front side of it, which is usually where it gets clogged up and not visible.

Thanks. But once I start driving and get air moving the temps go back to normal. If you still think thermostat, is that a difficult replacement?

 

[dorton]

Sounds like fan clutch isn’t locking up.

 

[AuSeeker]

Thanks. But once I start driving and get air moving the temps go back to normal. If you still think thermostat, is that a difficult replacement?

When you get more RPMs you also get more air moving, you also get more coolant moving, so it could still be either of what I mentioned above, but as mentioned by [MENTION=82455]dorton[/MENTION] , it could also be the fan clutch not working correctly by not engaging and spinning fast enough at idle but spins faster with more RPMs and moves more air.

I would start by checking for air in the cooling system by removing the radiator cap (not the reservoir cap) when the engine is cold and see if it's full of coolant, if it's low fill it with the proper coolant that is in it now (if you don't have any coolant use distilled water) and replace the cap and see how it does by driving it until it gets up to operating temperature.

(DO NOT remove the cap after you have started the engine until it's been off and had time to completely cool down or you risk getting scalded!!)

If it still overheats let it cool completely and check the coolant level in the radiator, if it's low again you definitely have air trapped in the system so repeat the above steps and try again and keep repeating this until it's still full after cooling down, if this works you're done and have fixed the issue, if it's full and still is overheating then you have other issues.

You don't sound like you can do any troubleshooting or work on it yourself so at this point you need to find someone you trust to check the fan clutch, or thermostat and or radiator for debris blocking air flow.

 

[DWilliam]

When you get more RPMs you also get more air moving, you also get more coolant moving, so it could still be either of what I mentioned above, but as mentioned by [MENTION=82455]dorton[/MENTION] , it could also be the fan clutch not working correctly by not engaging and spinning fast enough at idle but spins faster with more RPMs and moves more air.

I would start by checking for air in the cooling system by removing the radiator cap (not the reservoir cap) when the engine is cold and see if it's full of coolant, if it's low fill it with the proper coolant that is in it now (if you don't have any coolant use distilled water) and replace the cap and see how it does by driving it until it gets up to operating temperature.

(DO NOT remove the cap after you have started the engine until it's been off and had time to completely cool down or you risk getting scalded!!)

If it still overheats let it cool completely and check the coolant level in the radiator, if it's low again you definitely have air trapped in the system so repeat the above steps and try again and keep repeating this until it's still full after cooling down, if this works you're done and have fixed the issue, if it's full and still is overheating then you have other issues.

You don't sound like you can do any troubleshooting or work on it yourself so at this point you need to find someone you trust to check the fan clutch, or thermostat and or radiator for debris blocking air flow.

Thanks. Coolant was a little low so I topped it off. New fan clutch is on the way. Timmy’s video looked straight forward so I’ll take care of it next weekend.

 

[brillo_76]

Sounds like fan clutch isn’t locking up.

Agree. If everything else is checking out ok.. The fan clutch sounds like it is not enabling when sitting idle like its supposed too.

 

[diverscale]

if you can't hear your fan clutch woooooooof really hard when your engine is getting hot, you got your problem for sure.

If after that your problem persists, might be the thermostat, often seen them not opening up enough so you get your situation.

If you want to drive this one off a cliff for that kind of problem, good luck trouble shooting some "modern" 2020+ vehicle, you'll want to drive it down a volcano.

 

[JoeT4R]

Definitely sounds like a bad fan clutch to me! I replaced mine a few years ago with 300K plus on the original. Haven't had an issue since. I highly recommend an Aisin unit, they're inexpensive and can be had from RockAuto the last I saw

 

[TheFastChef]

if you can't hear your fan clutch woooooooof really hard when your engine is getting hot, you got your problem for sure.

If after that your problem persists, might be the thermostat, often seen them not opening up enough so you get your situation.

So, I have a similar issue: the car overheated while charging the AC, just at idle. Thought it was ok (not sure) as it got better when driving. Seemed fine with the AC on. But yesterday, it was raining, i was parked and had the ac on when suddenly it was steaming out from under the hood! I started driving, it immediately stopped and the temp dropped. Went home with no problem.

Thing is, I had a new radiator put in perhaps 3-4 years ago, and just 3000 miles ago I had a new crate motor put in. So its all new. Starter, alternator, almost everything.

So, tell me about how I would know its the clutch fan, as it spins at idle. I'm supposed to hear it make a sound, when? Its already spinning, so does it engage and start spinning......faster? Harder?
So I have a new water pump, and thermostat, so highly unlikely.
With a new motor, was there a new clutch fan? I don't even remember, i though it was the water pump on back.
I'm very disappointed, as you can imagine I spent a lot and its running smooth as silk, aside from this issue!!!!!!!!!!!!
The book says the radiator cap might not be pressurizing, and of course that not new. How can I tell? The book says "have it checked" but for what they cost, I'd just replace the cap.
Jiggle valve on the thermostat??? its been 3000 miles and its been fine, although I didn't realize they drained and never refilled the AC, so once we did that 2 weeks ago it overheated.

Any advice?

 

[TheFastChef]

It's possible that when they did the head gasket the thermostat is installed incorrectly with the "jiggle valve" in the wrong position and not allowing all the air to burp out of the system, or either it just may need to be burped to get any remaining air out.

Also check the radiator to see if any debris is blocking air flow, you may need to remove the radiator to get at any debris that is on the AC condenser/front side of it, which is usually where it gets clogged up and not visible.

I have a new motor with about 3k, so the "jiggle valve"? You mentioned
"any debris is blocking air flow, you may need to remove the radiator to get at any debris that is on the AC condenser/front side of it, which is usually where it gets clogged up and not visible"
Where is that? You mentioned the FRONT SIDE of the condenser. Do you mean internally? I have a new radiator (4 years) and there is nothing visable, no leaves no dirt, no debris. Unless you mean internal.
But no, there is nothing blocking the air flow, everything is very clean and like new.

 

[AuSeeker]

It's possible that when they did the head gasket the thermostat is installed incorrectly with the "jiggle valve" in the wrong position and not allowing all the air to burp out of the system, or either it just may need to be burped to get any remaining air out.

Also check the radiator to see if any debris is blocking air flow, you may need to remove the radiator to get at any debris that is on the AC condenser/front side of it, which is usually where it gets clogged up and not visible.

I have a new motor with about 3k, so the "jiggle valve"? You mentioned
"any debris is blocking air flow, you may need to remove the radiator to get at any debris that is on the AC condenser/front side of it, which is usually where it gets clogged up and not visible"
Where is that? You mentioned the FRONT SIDE of the condenser. Do you mean internally? I have a new radiator (4 years) and there is nothing visable, no leaves no dirt, no debris. Unless you mean internal.
But no, there is nothing blocking the air flow, everything is very clean and like new.

When I said "front side" it is referring to the front side of the radiator which you can't see because of the AC condenser is in front of the radiator so the radiator may need to be removed to see and clean the front of the radiator coils if needed.

Not sure if you're asking a question about the "jiggle valve" or not?

 

[phattyduck]

So, tell me about how I would know its the clutch fan, as it spins at idle. I'm supposed to hear it make a sound, when? Its already spinning, so does it engage and start spinning......faster? Harder?

Most of the time, the fan should be silent. If if the clutch is locked up (radiator or AC putting a lot of heat into the front heat exchangers), then when the engine is rev'd it will sound like a giant fan in the engine bay. You won't be able to tell a difference audibly at idle, but it does also change the fan speed even at idle.

A correctly working stock cooling system on the 3rd gen will keep it from overheating in basically any "daily driver" situation you can imagine.

-Charlie

 

[2TH4IST]

I'll chime in here. So back when I was welding up my front bumper I had found the ac condenser was rotted out. All the fins were falling off or plugging the natural air flow. Depending what your 4runner has seen that my be the case. These are 20+ year old rigs. After that amount of time stuff needs to be replaced, that includes, fan clutch, radiator, ac condenser, t-stat, coolant (correct type too).