Stabilizing Cooling Temps With A/C Fan???

[cfiiman]

Hey everyone,

I have a question and I have searched for an answer and can't find consensus so thought I'd post. I read in a thread about turning on the A/C (since it runs the fan) to stabilize your temps in traffic. Now this seems strange to me b/c the a/c should raise your temps but I guess since the fan comes on it "could be" a wash I would think this would only be true on a mild day, say 70* or so, just a guess here I have no idea. It was low 50's and sunny yesterday so I decided to test my theory after a long drive when I got back to my driveway. My car always runs at 190* unless I'm in traffic, then it goes up and the fan kicks on even on cold days. Anyway, I kicked the a/c on and let her run and the temp did indeed stay around 195 or so (again, normally it would've rose with no airflow to when the fan normally kicks on around 220-225* I think), but again it was only 50'ish outside which I'm sure substantially helped. So at what point does the a/c add more heat than the fan can remove? Obviously with my test it helps on a 50'ish day, but do any of you see cooling effects in anything higher, say 70 to 80 or even 90 or is that when turning the a/c on will add heat to the system. I'm planning on getting the ROE fan kit but if just turning the a/c on will do the same thing say at below 85 or even 90*, then I probably will just use that b/c I rarely drive a vert in really hot weather, just too damn uncomfortable lol. Thanks for any thoughts.

 

[plumcrazy]

i think the roe battery drain kit only turns the fan on AFTER the car is shut off. to help it cool then, not during driving. might wanna search dave666 's posts for more info on cooling

 

[cfiiman]

Plum, I did that was one of the threads I looked at. And I think you are mistaken on the fan kit, you set the temp and it comes on while driving and also when you shut the car off (which I don't like the fact it does it with the car off b/c of the "drain" you mentioned.

 

[LifeIsGood]

From Sean's website...

NEW! Now features full adjustability to activate your radiator fan at any temperature you desire while the engine is running! When you shut your Viper's engine off, the radiator fan stops running, no matter how hot the engine may be. Our kit automatically combats heat soak by cycling the radiator fan on as needed. A natural flow is created when the cooler water in the radiator sinks and is replaced by hot water through the upper radiator hose. All components needed for installation are included. Installation is easy! Done with simple hand tools in less than 30 minutes! No cutting, drilling or soldering required. All high quality components including fused relay and stainless steel sealed temperature sensor. Helps protect your investment! 12 month warranty, 30 day money back satisfaction guarantee. Fits 1996-2002 GTS and 1996-2002 RT/10 models

Plum...you're going to have to stop telling stories. Seriously, I've never had a battery issue while using the fan control kit (it's been on my viper for 2 years), but I do use a trickle charger. I know that the fan comes on and runs only a few times after I shut the engine off.

 

[cfiiman]

Ok before this turns into a thread on the ROE kit, I really am only wondering peoples experience using the AC option on their car and at what point, if any, they have found it effective or not effective in controlling higher temps on the gauge, thanks!!!

 

[plumcrazy]

thats a new feature ? i dont remember the one i had years ago being adj like that.

IIRC, dave found a much better way to connect it. maybe it was better connectors ?

FYI, an SCT tune can change the temps too.

 

[LifeIsGood]

I'm not an expert, but some may need more info...what viper model/year/mods...the answers to these questions will probably make a difference in the answer to your question.

 

[mjorgensen Woodhouse]

I have always used the A/C on high to cool my cars after a session at the track or after an autocross run, works very well IMO.

 

[cfiiman]

Sorry Stock 94, have no problems with cooling, seems normal from who I talk to and read, while there is flow it stays on 190, in traffic it cycles through the "goes up, fan kicks on, goes down" kinda thing, I was just interested when I tested it yesterday in the driveway and it stabilized it at 190 b/c the fan was on.

 

[cfiiman]

I have always used the A/C on high to cool my cars after a session at the track or after an autocross run, works very well IMO.

Great to know! What are the temps when you are doing that? And does it actually bring it down, or just stabilize it where it is at or

 

[mjorgensen Woodhouse]

I generally get a 10-15 degree drop from where it is quickly and then stabilizes after that. Gen2 cars have always run hotter though so 215-220 is nothing in my book. If you are really concerned about a temp then do A/C and full hot temp control. You will get the fan on and the heater core dissipating heat also. Not so comfortable when it is really hot out, but if you need to you can do it to cool things down.

Great to know! What are the temps when you are doing that? And does it actually bring it down, or just stabilize it where it is at or

 

[X-Metal]

what mark said.
plus you could aways add a switch with a relay to allow you to turn on the fan whenever you want. then you wouldnt have the heat from the ac condensor soaking into the radiator.

 

[cfiiman]

I generally get a 10-15 degree drop from where it is quickly and then stabilizes after that. Gen2 cars have always run hotter though so 215-220 is nothing in my book. If you are really concerned about a temp then do A/C and full hot temp control. You will get the fan on and the heater core dissipating heat also. Not so comfortable when it is really hot out, but if you need to you can do it to cool things down.

Great info, this is exactly what I was looking for. One last question for you, you say you get a drop, then stabilize, where is the stabilizing point temperature wise? I'm sure it is different with different ambient air temps but in general, are we talking 100* days, or 90 or 80 etc. and does it stabilize around 200 or 210 or? Thanks so much for the info/help!

what mark said.
plus you could aways add a switch with a relay to allow you to turn on the fan whenever you want. then you wouldnt have the heat from the ac condensor soaking into the radiator.

Right, when you say "add a switch" are you talking about the ROE unit or just putting something in line your self that is manually activated inside the cockpit?

 

[cfiiman]

double post sorry, see above.

 

[X-Metal]

Great info, this is exactly what I was looking for. One last question for you, you say you get a drop, then stabilize, where is the stabilizing point temperature wise? I'm sure it is different with different ambient air temps but in general, are we talking 100* days, or 90 or 80 etc. and does it stabilize around 200 or 210 or? Thanks so much for the info/help!

also put a cooler tstat into it. for less than 50 bucks, it makes a HUGE difference.
i keep them in stock as one of the first mods i do

 

[cfiiman]

From everything I've read, doesn't the thermostat make 0 difference on the "running temps"? I know it will help as far as time getting to a given point but open is open isn't it?

 

[FrgMstr]

thats a new feature ? i dont remember the one i had years ago being adj like that.

I suggest you learn how to use the Search function properly before sounding off next time. Just kidding. Had to say it after seeing the recent public floggings.

 

[fqberful]

From everything I've read, doesn't the thermostat make 0 difference on the "running temps"? I know it will help as far as time getting to a given point but open is open isn't it?

When you change the TStat to a lower temp, you need to change the fan temps as well and then the water will control at a lower temp.

--FQB

 

[cfiiman]

When you change the TStat to a lower temp, you need to change the fan temps as well and then the water will control at a lower temp.

--FQB

Ahhh I see.

 

[LifeIsGood]

Now that's funny.

thats a new feature ? i dont remember the one i had years ago being adj like that.

I suggest you learn how to use the Search function properly before sounding off next time. Just kidding. Had to say it after seeing the recent public floggings.

 

[dave6666]

My playground is 110 degrees. Oh I'm sorry, 111

I redesigned my cooling system with 3 fans and a control system that no longer uses the factory thermostat. I did a very detailed writeup on it if anyone is interested. $250 mod for the fans and controls.

The temp of my car goes up with the AC on. Nothing like prewarming the 110 degree air with the condensor coils at 175 degrees LOL

Oops, I meant 111 degrees

You must be registered for see images

 

[dave6666]

also put a cooler tstat into it. for less than 50 bucks, it makes a HUGE difference.
i keep them in stock as one of the first mods i do

Won't make a bit of difference in Texas stuck in traffic where the pavement temps are in excess of 150 degrees. You need air moving not a thermostat change to cool the car under those conditions.

 

[X-Metal]

Won't make a bit of difference in Texas stuck in traffic where the pavement temps are in excess of 150 degrees. You need air moving not a thermostat change to cool the car under those conditions.

in traffic-not a lot no, but it will allow the water to reach the radiator 40 degrees faster which would allow the car to operate cooler and keep the tempature from escalating at a faster rate. which would you rather have on black top with the clock ticking? an engine who is starting off at 160 degrees or one that starts off at 195 degree?
ill take the 30 degree cooler one. it buys some time until you get the car moving again.
i deal with racing engines on a dailey basis. thats my career. so yes, i do KNOW that a cooler t-stat will allow the engine to run cooler. you are allowing the engine to disapate its heat energy at a faster/cooler rate.
and here where i live it does reach over 100 degrees dailey in the summer. and i spend a LOT of time road race courses where the black top is always 130 degrees plus. so anytime you can get water into the radiator quicker, it helps.

 

[cfiiman]

Well looks like I'll just have to test it out to see how it works at higher temps as they continue rising where I am towards spring. I don't like driving a car without a top (fun car) in oppresive heat so I don't really see 100* or even 90* as an issue, but in the 80's I'll be out and will be out at night so if kicking on the a/c will keep it at say below 200 or so I'm fine with that. I guess the real question is how often can you turn the compressor on without doing damage? I mean I know turning it off and on is not good for it so it would only be something I would turn on and leave on for the foreseeable traffic but just curious how long between turning it off is safe to turn a compressor back on, I've always used the 5 minute rule but don't know where I picked that up.

 

[Steve-Indy]

cfiiman, you may want to review this old thread concerning your HVAC controls and air flow (Gen I and II cars far different than Gen III and IV)...settings, cool air, hot air, heater core, water valve, etc:

http://forums.viperclub.org/rt-10-gts-discussions/620571-question-heat.html

There is far greater collective Viper experience in the above referenced thread than some...including a Chrysler employee who works with cooling systems.

 

[cfiiman]

cfiiman, you may want to review this old thread concerning your HVAC controls and air flow (Gen I and II cars far different than Gen III and IV)...settings, cool air, hot air, heater core, water valve, etc:

http://forums.viperclub.org/rt-10-gts-discussions/620571-question-heat.html

There is far greater collective Viper experience in the above referenced thread than some...including a Chrysler employee who works with cooling systems.

Steve, thanks, and nice read, I've been getting very familiar with the system. I'm still just wondering at what ambient air temp. the ac being on so the fan comes on is effective at stoping temperature increases. I know it is effective in the 50's hoping it would be for maybe 80's but having heard anything yet from anyone on that Basically is the ROE kit needed if the a/c can stabilize the temps below a certain ambient air temperature is the real question.

 

[vprtech]

I agree with dave6666 , the only way to effectively cool down then engine is to get more air flow through the radiator. We have a kit that adds two additional cooling fans in front of the A/C condenser to push the air through, in effect boosting the stock cooling fans capability. It makes a considerable difference. If you car is constantly running at 220 degrees and you have a 195 degree thermostat and decide to install a 170 degree thermostat , it's is not going to help as both thermostats are wide open, you have simply reached the limit of the cooling systems capability to transfer heat out of the engine. On other benefit to increasing air flow through the radiator, as dave6666 can probably confirm , is that it helps the A/C performance at low vehicle speeds as well.

- Chris

DC Performance: Proven Performance

 

[DarcShadow]

Just currious, why are you concerned? If you're just driving around town what exactly is your concern with the standard fan kicking on at higher temp then shutting off once it gets below the factory setting? If the fan shuts off on it's own clearly the system is designed to tolerate that temp. Running the AC just to cool the engine seems like a waste/strain on systems unecessarly. Now if you're at the track and pushing it hard I complety understand doing anything necessary to keep the car a cool as possible and prevent deep heat soak.

Not trying to start anything, just currious as to your reasoning for wanting a steady/constant engine temp.

 

[cfiiman]

Darcshadow, well, to be honest maybe I shouldn't be concerned, it has never gone into the "yellow" maybe it is just a confort thing. I certainly would like the car to stay below 200 when I stop but guess it is just a personal thing. I guess I get a bit of an "uneasy" feeling that as it creeps up just before the yellow that it will actually stop there. Guess honestly it just comes down to that I would like to control the temp a bit more by being able to kick the fan on early like with the ROE kit, but when I came across the thread talking about stabilizing by kicking on the a/c I guess I just went "hmmmm" if that makes sense.

 

[plumcrazy]

Now that's funny.

hurtful but hilarious