LSx coupe running too hot w/AC on. Any tips?

[dville_gt]

I am already running the larger LT1 radiator w/the factory dual fan setup (supposed to push 8500cfm w/both on). The car just slowly but surely rises up to about 225* when cruising around and will eventually go over 230 if you get into stop and go driving. Right when I turn the A/C on the temps start rising, car is fine A/C off.

Did the Mustangs have a factory air deflector for the radiator? Mine doesn't have one, anyone got one laying around? Only problem with this theory is that I can't imagine an air deflector helping much at idle.

I am sure my uncoated 1 7/8th long tubes are not helping anything, but with a cowl hood I'd think it would at least give the hot air somewhere to go.

I assume if the air defector doesn't solve it the only other thing I can think of to solve a car that is getting too hot even at speed would be a larger radiator. There is one on eBay that has good reviews for about $240, but I'd rather exhaust other options before I do that.

[XR_1]

First thing is replacing your radiator cap and switching to a true 160-180 thermostat.

I don't run a thermostat but do run a restrictor (I just cut the back and spring off the thermostat)
I also made the hole on the bottom of the bumper bigger (I will post pics later) and I added a mach chin spoiler (more for aero)
Last thing I will do but havent had a chance to do is open up the hole on the cowl hood (I have a Cervinis and it has a tiny hole)

Before this I normally ran 220 and then 230 when I pushed it alot
Now it runs at 200* in todays weather

Maybe this things will help, Good luck

[dville_gt]

Thanks XR_1, good tips.

Can an overcharged A/C system cause a car to overheat?

[Baron Von Crowder]

Obviously, check both fans to make sure they are both on with the a/c running. I had one doing something similar, and the alternator wasn't putting out enough at idle to run the fans full speed. Something to think about, if its 105* in the shade, its 120+ in the sun. I hopped in the racecar to move it the other day and the coolant temp was 130 before I fired it up. Can't get as much cooling pulling hot air through the radiator.

[Denny]

I'm not sure exactly the temp range, but all my LSx cars have run hotter than anything else. I was thinking like 205 or 210ish, though.

[dville_gt]

Obviously, check both fans to make sure they are both on with the a/c running. I had one doing something similar, and the alternator wasn't putting out enough at idle to run the fans full speed. Something to think about, if its 105* in the shade, its 120+ in the sun. I hopped in the racecar to move it the other day and the coolant temp was 130 before I fired it up. Can't get as much cooling pulling hot air through the radiator.

Ya, both the fans are pulling through the radiator, I have both set to be on all the time w/ac on (up to 40mph then they cut off). Car has a 140amp alternator and the voltage stays steady at around 13.8v no matter what I have on/off.

I agree about it just being hot as hell, the times when it is getting hot are typically around 4-5pm when it is the hottest part of the day. My IAT's before I even started the car (sitting in the garage) were 107* (eventually rising to 140* before the end of my trip and this measurement is inside the drivers fenderwell). I'd just really like to get the car to be trustworthy at any temperature. It hasn't ever "over heated", but I don't like worrying at all.

I'm not sure exactly the temp range, but all my LSx cars have run hotter than anything else. I was thinking like 205 or 210ish, though.

Ya, I just hate being nervous about anything. I like to build them where they can be trusted to sit and idle in the heat w/the a/c on. Car is trustworthy with the A/C off.



So does anyone think that an overcharged A/C system could cause enough heat in the condenser to overheat the car?

Also, anyone got an air deflector for a fox?

[dville_gt]

What do you guys think about this?

High Discharge Temperature
Too much freon in the system will backup and flood the inside of the condenser surface area, leading to temperatures typically over 240 degrees. The flooding reduces the condenser capacity, and since the liquid can not be cooled because of the smaller area, the heat and head pressure rises. Too much liquid freon that collects in the bottom of the compressor will also cause high sub-cooling.

Reason I ask is because I had to add some freon to my system w/out a manifold set, reason being my PCM didn't command the fans on w/the ac (stupid tune wanted to see a/c pressure rather then a/c command). Anyways, this caused my highside to go way to high and it vented some freon. This made the system start to cycle a bit so I had a can sitting around and added it to the low side. I think I might have overcharged the system as it is "cool" but not super cold and the car is getting hot.

Going to have to get with Buick355 soon anyways since my daily driver just crapped its compressor on me so maybe I'll bring the coupe back by and see how overcharged the system is.

[Lason]

Did you pull a vacume before you filled the system originally?

[dville_gt]

Did you pull a vacume before you filled the system originally?

Ya, the system was charged correctly initially, it just vented off some freon when the fans failed to come on and I added some via a can. Unfortunately I don't have a manifold gauge set so I just went off of the low side pressure (I know, I know, this is stupid). I am afraid I might have over-filled it and this is causing the additional heat that is leading to me seeing ECT's going straight up when the A/C is on.

[shumpertdavid]

I don't think being a little overcharged will add too much to your engine temps. I've pulled as much as 2 lbs extra out of an ac system without any overheating problems. The only issue was lack of cold air. I'd venture to say you'll need more radiator and a cooler thermostat as Xr-1 advised. Was the radiator you put in new or used? If used it could have some blockage in it.

[dville_gt]

I don't think being a little overcharged will add too much to your engine temps. I've pulled as much as 2 lbs extra out of an ac system without any overheating problems. The only issue was lack of cold air. I'd venture to say you'll need more radiator and a cooler thermostat as Xr-1 advised. Was the radiator you put in new or used? If used it could have some blockage in it.

Used. I've always understood that cooler thermostats actually decrease the cooling abilities as they do not allow the coolant to stay in the radiator long enough. I guess this is a moot point since the factory t-stat opens at 186* thus is staying open the entire time anyways.

As for the radiator it was used, it is the wider LT1 style and I do not see any gunk or blockage when I look down the side tank (not that is any real indication).

I've never had a car that A/C makes such a huge impact on, when I go through my data logs I can see exactly when I turned on the a/c as the temps just start to steadily rise 1 degree at a time right after I turn the a/c on.

[Denny]

Well, if you get a front air deflector, you'll probably drop it back into the range I said my LSx-based vehicles have run. It might be as simple as that.

[dville_gt]

Ya, I was hoping someone might have one that they took off or something, I guess I'll have to just shell out the $45 to LMR and buy a new one. Just doesn't seem likely to help at idle.

[jw33]

Are the fans sealed up aganst the radiator so that all the air is pulled through the core? Assuming you have the tune in the ballpark I don't see why it's running hot. My car actually ran too cold and I had to dial back the fans even in the summer, but mine doesn't have A/C either. I'm sure you've already said somewhere, but what thermostat, radiator cap, and coolant are you running?

[dville_gt]

Are the fans sealed up aganst the radiator so that all the air is pulled through the core? Assuming you have the tune in the ballpark I don't see why it's running hot. My car actually ran too cold and I had to dial back the fans even in the summer, but mine doesn't have A/C either. I'm sure you've already said somewhere, but what thermostat, radiator cap, and coolant are you running?

Fans are sealed up good to the radiator, I've gotten the tune pretty much perfect averaging 1-2% AFR error (on the rich side of stoich). I have both the fans set to run full time up to 45mph.

Stock 186* thermo, stock lt1/ls1 gm radiator cap (believe it is set for around 18psi stock), running regular ethylene glycol green stuff 50/50 with distilled water.