A/C blows hot at higher engine temps

Sorry to start another thread on this guys but I have scoured the others and no ones problem sounds identical to mine. My average coolant temp day to day is about 184-186 degrees. On hotter days (100+ degrees in Texas) the temp will get as high as 220 degrees. Around 216 and up my A/C will begin blowing hot air. I’ve had the A/C checked and recharged at the dealership, I’ve personally replaced the thermostat, water pump and fan clutch. I’m at a loss for what it could be. Any help would be appreciated. Thanks.

 

Almost 40 degree variation? Wow. I thought mine was bad. On a cool morning, under normal driving, my temp stays in the 195-197 range. 100+ degree weather, or under heavier acceleration, I've seen as high as 203. But never outside of that range. Radiator maybe?

 

That was my suspicion, but I’ve flushed the coolant twice. Granted, not with distilled water but the coolant looked fairly clean both times. I’ve used the orielly premix coolant each time along with the special coolant funnel to check for air bubbles.

 

180* stat, that sounds about right

That's not right. Some rise is to be expected, but no where near that much.

Have you pressure tested the system? Not that you're having coolant loss, but just to see what it reads?

When it gets hot, have you turned on the heat full blast to see if the temp will drop by using this 'second radiator'?

Is the condensor and radiator clean on the outside, nothing jammed between them (mud, hay, etc) or in the fins?

Do things change between open air cruising speeds and stop/go driving?

IMHO the key here is to solve the cooling system situation (before you blow a headgasket) and then see what happens with the AC.

 

Yes sir I have tried the heater method and it slowly lowers the coolant temp. I’ve cleaned the coils on the exterior before. I have not done a pressure test, and I don’t seem to be losing coolant, no weird stuff in my oil or fouled plugs. I haven’t seen any signs to suggest a head gasket so far. Would the color change kit to detect exhaust leak be a viable option as well?

 

I should also add that this is really prominent at idle. I’m a homebuilding superintendent so I spend a lot of time in my “mobile office” a.k.a. My truck. Once I start driving, it will get the coolant back down in the 195-210 range and the AC will blow cool again.

 

Airflow maybe? Fan/shroud, anything blocking the radiator?

 

I don't suggest you have a blown head gasket. Yet. Just want to avoid that.

You might try pulling the tstat and see what happens. Not that you should stay that way, as the ECU wants temp to change fuel mix. But if it's easy for you to do, it's worth a shot. I know you said it was new, but improper placement, or even being bad out of the both are possible.

Can you see flow in the radiator when the cap is off (remove cap cold, then watch as it warms). This gives some comfort that the new water pump is pumping. And double checking that new fan clutch for engagement isn't a bad idea either.

I've also seen lower radiator hoses collapse at higher RPMs/flow, creating an almost instant restriction and heat rise. So do your hoses seem firm and pliable, but not mushy?

 

New info. Important. That screams fan. Forced air from driving makes things right, while idleing is dependent on the fan.

 

I used an OEM denso fan clutch. Are they likely to be bad out of the box? I will give it a couple tests to see if it is out, it didn’t occur to me to recheck that because it was new. Thank you for all your help so far sir.

 

Using the Zerex Asian stuff? Not sure it matters, remember there was some reason to use it, lol. Electric fans may help? Not sure if thats an option for our trucks or not. If it matters, mine is pretty shitty cooling at a standstill (not moving). Always has been.

 

Tomorrow morning before you start the engine for the first time, try spinning the fan blades by hand. If there's little movement, the clutch is likely OK. If it spins freely on a cold engine, it's likely tired.
Some people say a healthy fan clutch should roar when engaged. I've seen that happen on some european cars, but have yet to get a noticeable roar from my Tacoma or the wife 4Runner.

 

I will definitely give that a shot. I’ve never heard a roar either. I have a buddy whose F-150 sounds like a swamp boat when it engages.

 

My wifes old Explorer and parents F250 was like that. But i figured out it was those extra electric fan(s) making all the noise. We lack those on our Tacomas. Funny to note though, her 2019 Highlander does have the additional electric fans and cools hella better than my Tacoma ever did. Maybe i need to look into those damn fans, lol.

 

I’ve never even looked into them man. Didn’t think it was an option given how little room there is.

 

Mine has done this as well, while driving through the desert portion of I-8. Had to turn the A/C off actually to keep the engine temps from climbing any higher.

My best recommendation is the CSF Radiator upgrade, with a 170° t-stat. A better electric fan setup would also benefit the system. Simply put, your lack of airflow is over taxing that thin OEM radiator.

 

After leaving the grocery store awhile ago, I drove about 40 miles in the same kind of heat the OP describes. Engine definitely warmed up on return.
Hood up - rolled down the drivers side window- reached in to turn off ignition. Fan blades stopped on a dime.

So in the case of my '15 4.0L Tacoma, the fan blades have a great deal of resistance when spinning them when engine is cold and stop immediately when I shut off a fully warmed up motor.

 

Just for info.............

https://help.summitracing.com/app/answers/detail/a_id/5272/~/how-does-a-fan-clutch-work?

 

My 3.4 2000 4Runner roars when you start it.

 

Dude we’re in TX my truck struggles as well. Cruising home today the ac was cool but not cold everything Cooling and AC system is in good working order.