Cooling the LT1 with AC.

[dhen]

I have a minor cooling problem. The way my car's AC is set up, it's either on full blast or not at all. Now here in Texas, that's not a problem when I'm driving down the highway, but when I'm sitting traffic on a hot day, my temperature will start to rise and if I don't turn off the AC after a while the coolant will start to spill out and eventually the engine will overheat.

If I leave the AC off, the car can idle all day long.

It's not really feasible for me to get the AC to work right, as I'd have to pay someone to try to get the Jag. climate control to work with the LT1 system properly. I imagine that this would cost hundreds and I kind of like my ice cold AC. (It blows 40 degrees - very nice.)

I have a stock Camaro radiator (new), iron heads, ceramic coated headers, stock Camaro fans, and an oil cooler. The problem is obviously when there's no air flowing through the engine bay. The engine is used (80,000 mi), so it's possible that there is gunk in there, but since it works fine without the AC, I don't think that's my issue.

What would you guys recommend so I can keep my ice cold AC and sit in traffic, which unfortunately I have to do a lot. I know that iron heads hold heat in more, but I don't think they do this enough to cause this.

This radiator would probably fix my problem, but at $500, it better:
http://www.summitracing.com/parts/BCI-60028/

Any ideas?

Edit:

Is this hose to the throttle body absolutely necessary? I can find some affordable aftermarket radiators if I don't have to use it.

http://img703.imageshack.us/img703/52/hoseh.jpg (http://img703.imageshack.us/i/hoseh.jpg/)

[95formula383lt1]

no u can run that hose straight to the rad an cap the tb. i recently had the same issue with my car getting hot with the ac on it would creep up on 210 and 220 i replaced the temp gauge sender and bled the system and have had no issue since stays right at 180 all day long. doubt your issue is the same but never hurts to check into it.

[Tarheel'Z']

wierd since my car runs cooler when the air is on,,i assumed it was due to the condenser fan running,,my car will get warmer when sitting in traffic and if i cut air on i can watch the guage go back down,,
are you sure your fans are functioning correctly?

[dhen]

I bled the system and the fans are working correctly. Search on eBay, it seems that big block Chevy radiators are the same height and width as LT1 radiators.

These are cheap. Any thoughts?

http://cgi.ebay.com/ebaymotors/HP-Aluminum-Radiator-Small-Big-Block-Chevy-sb-sbc-31-/200577261383?pt=Motors_Car_Truck_Parts_Accessories&hash=item2eb3561f47

http://cgi.ebay.com/ebaymotors/2-Row-Aluminum-Radiator-67-69-Camaro-Firebird-Big-Block-/150525859528?pt=Motors_Car_Truck_Parts_Accessories&hash=item230c0a56c8

[Tarheel'Z']

im not understanding what the ac has to do with the radiator?

i could undersdtand it if you said simply the car was overheating but you said it only happens when the air is on right?

you kinda contradict yourself a little as you say the car will idle all day without the ac on but then you say the problem is obviously no air flowing through engine bay,,so how does it idle all day?

[black heartbeat]

the ac doesn't have anything to do with the radiator besides the fact that the condenser is in front of it and whether its on or not wouldnt have an effect on its operation....so I'm very confused. If anything i would think that the cold lines would....well cool the engine down lol. It honestly makes me think that you have low or bad coolant. Are there any whines the engine makes? maybe the compressor is somehow putting strain on the waterpump when it kicks on or something?

[dhen]

I'm not sure what to say. It's a known fact that air conditioning causes the engine to work harder and hotter. The condenser in front gives off heat and if your cooling system is marginal this can cause problems. According to the guy who sold me the kit that I used to do the swap, there's a high/low pressure sensor on the LT1 A/C system that tells the PCM when to shut the compressor off because the pressure is too high and is causing the condenser to give off more heat than is necessary. My setup doesn't have it and so it runs full blast. Setting it up to work properly would be a real PITA and since I can't do it myself would also be expensive.

When you're driving down the road there are positive and negative air flow issues at work that move air out of the engine bay. When you're parked, especially when running A/C, this really works your cooling system hard. Since my car is kind of DIY, this can cause problems that you wouldn't have in an F-body LT1.

Anyway, does anyone have any thoughts about the radiators I linked to and/or some other mods that would keep this thing cool in traffic? Removing the hood would solve the problem, as it would allow the hot air to escape, but that's obviously not an option.

The problem I'm having is only when I'm been sitting in traffic in mid-90s weather parked on hot asphalt for more than 20 minutes. It's not something that keeps me from enjoying my car 95% of the time.

[Tarheel'Z']

well known fact or not it doesnt happen on my car that way,,when i run my ac the condensor fan runs which also pulls air through the radiator which helps keep the motor cool,,,my issue is if you say its the ac making it hot how is a different radiator gonna help??
what are your rpm's at idle with air on? do they drop real low? maybe so low that the water pump isnt turning enough to keep up?

air flow issues when sitting still tell me theres a fan problem
air doesnt flow through an f-body sitting still either thats what the fans are for
other than that i dont have any thing to add that would help sorry

[Chris]

I don't know who tuned your pcm to not have low/high pressure switches, though the way a air conditioning unit works it by cycling through high/low pressure systems. That sensor isn't their for priority #1 seeing engine load. Your are building up tons of pressure leaving that pump running like that and I bet it wont be long until you blow a hose.

Are you running your fans while driving down the road?

[dhen]

The high/low pressure sensor wasn't installed by the guy that did the hardware for the A/C. As far as I know, it's not a tuning issue, but it was Salomon who did the tune.

I can't hear my fans when I'm actually driving, but my understanding is that they cut out at a certain MPH.

[Chris]

I am thinking its more of an issue with the pump staying on and putting a huge load on the motor because of the pressures you are creating in the Ac system.

[dhen]

I am thinking its more of an issue with the pump staying on and putting a huge load on the motor because of the pressures you are creating in the Ac system.

That's what the guy who sells the kit was saying. Do you think a bigger radiator would keep the temps down, though?

I understand that this isn't the proper way to fix it, but I'm on a budget and paying someone to solve it would really be expensive.

[Chris]

No, produce some lines that have the correct sensors in them so you dont end up blowing a compressor to piece or a line

[dhen]

I've been doing some more research since I've never messed with A/C before. It looks like the pressure sensor just screws in onto the Schrader valve on the dryer and has two wires that I could tap into the wires that come off of the compressor. Am I missing something here?

[95formula383lt1]

bigger rad would be no help.

[lt1-xjs]

That's what the guy who sells the kit was saying. Do you think a bigger radiator would keep the temps down, though?

I understand that this isn't the proper way to fix it, but I'm on a budget and paying someone to solve it would really be expensive.
Mine had a 31" x19" radiator from the start, it developed a leak so I replaced it with a Griffin race one. A 31" x 19" 1 1/4" two row rated for 400- 600 hp. I used half of the Jaguar shroud and installed a single 17" fan from a late 80's Camaro. Temps run 160*- 180*. It was only $350 made to my specs. If you have room go bigger.

[dhen]

If you have room go bigger.

That's what a British car mechanic here told me. Apparently, even BMWs and Land Rovers here have problems with our heat. They're just not designed for it.

I went with this bad boy:


http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=160568697342&ssPageName=STRK:MEWNX:IT

I did the math and it has just a fraction under twice as much cooling volume. I figure if it can cool a big block Chevy, it should do OK with my small block. Can't hurt anyway.

Something I just thought about today, but I wonder if my tune has something to do with my temps. It was tuned by Salomon to save on gas a little, which means it's a little lean.

I'll let you know what happens. Thanks to everyone who replied.

[Chris]

Does your air condition freeze you out of the car if you leave it on 24/7?

[dhen]

Does your air condition freeze you out of the car if you leave it on 24/7?

No. It always runs at 40 degrees Fahrenheit, but never freezes. I'm not sure what it's sensing, but the fact that it's so consistent tells me the PCM is involved. The only time it goes warmer is when the car starts to overheat.

The same mechanic I talked about earlier said his BMW will do this in traffic and he just ups the RPM to get the water to circulate more.