My 1987 is starting to overheat whenever I'm not in motion. If I'm waiting in a drive thru line or in a line of traffic, even for a short amount of time, the temperature starts rising on my Water and Oil. My husband put on a new thermostat, but that didn't do a thing! Also, my air conditioning will only blow cold air if the car is moving - when I'm stopped it will blow only hot air. Has anyone had this happen? Is it possible the two problems are related? Any help would be great. I've had this car for a long time and I love it, this is the first problems I've had and I'm hoping it won't be too difficult to correct. :confused:

 

Running hot in a vette is normal. What temperature thermostat did your husband put in?

What are your temps? do the fans come on at all at 225-230 coolant?

Best fixes:
160 thermostat, a bottle of Water Wetter in the radiator, radiator coolant flush, fan switch but i wouldnt wire the main fan to it, Reprogram the chip to make the fans come on sooner, clean the front of your radiator while its empty (this helps ALOT)

You do all that and your temps might not ever get above 210 again.

 

Thanks so much for your help! Not sure of the thermostat temperature, but I'll check. The fan comes on when the temperature gets about 240 to 245, my engine light came on once this weekend when it reached 261. As soon as I start moving, the temperature drops. Do you think this is affecting my A/C as well?

 

Take a look at the front of the radiator (thru the nose bottom), do you see a fan?

The (pri) fan at the rear of the radiator is controlled by the ECM (computer). The front (sec) fan is controlled by switch sensor in the cyl head, (stock~240'F).

From your description, you have a problem w/ the primary fan not coming on. This fan should be on very shortly after the compressor starts turning. If not, you have AC or fan problems. The primary fan should come on around 200'F. A new Tstat will not help an in-op fan.

I disagree that these cars run hot. Up your way, you should not see a problem. It is typical for the cavity between the AC condensor and the radiator to fill w/ road debris (leaves). Pop the top radiator shroud off and take a look.

Yes, it sounds like they are related. No air across the condensor, no cool air inside.

Fan does not come on,.... bad relay, bad fan, bad wiring, bad temp sensor.
I believe the fan relay is mounted to the dri side or the radiator. About the size of a couple golf *****.


[Modified by ZylaRace, 4:13 PM 6/10/2002]

 

240* is high for the main fan to turn on. My 89 would turn on about 220* with the stock chip in the ecm. The first check would be to see exactly when the main fan turns on. Then try with the AC on, the main fan should be on any time the AC is on (if freon is fully charged). Another check is to connect terminals A and B (above your knee when in the seat, top row farthest right two connectors) on the ALDL connector with a paper clip with key off, turn key on and fan should run. If it does not run under any of these tests post back.

Also if the radiator has never been removed and the space between the radiator and the condensor cleaned, that will help al whole lot! There is a tech tip (in tech tip section) about the proceedure to do this.

Good Luck

Pete

 

I think the primary fan is programmed from the factory to come on at 228, the secondary fan (if it has one) comes on at 238.

 

Fan comes on with a high pressure switch on the a/c --does not run all the time --unless your head pressure is too high all the time (not good). Sounds like a typical main fan failure here --have changed truckloads of them.

 

261 is wayyyy too hot for aluminum heads, you have some cooling problem somewhere. Check your option codes (either in the console, or in the compartment behind the drivers' seat) for the B4P option, this means you have another small fan in front of the radiator and you could see it if you look under the nose. It sounds like that fan isnt even coming on, and the main fan is coming on late. This would definitely affect your AC.

 

Welcme to the forum Pamela. You will like it here.

 

To add to this I'll say check the fans very closely...

I had a fan go bad on my old TPI IROC Camaro... The fan would run but at a very reduced speed... It took quite a while for me to troubleshoot my overheating problem because I just glanced at the fan and assumed it was OK because it was turning... After I replaced the fan motor the engine ran cool again... The old motor was just short of being frozen and would turn by hand with quite a bit of effort....

Also you can get a cooler temp fan switch... I put a low temp fan switch in to replace the factory 238F switch... I left the stock thermostat so the fans would actually run a few minutes before the thermostat even opened... It worked out well as the car ran a rock solid 200F according to my gauge whether cruising down the freeway or stopped in traffic during the summer...

Sure sounds like a fan problem since your A/C is hot as well...

 

Actually yeah that is a little hot for a vette. While he's right, running at hot temps in a vette IS pretty normal as GM did this to burn emissions better, it's not the most efficient way for a VETTE to run if performance is an issue and not "tree hugging" if you get what I'm sayin. Actually on your L98 what I would suggest is what I did...............get a MANUAL FAN Switch to kick on your fans while in mid traffic. I would ask yer mechanic if you have one whether he'd recommend the 160 stat though. I personally wouldn't recommend em for L98's as they have to hit Open Loop mode in the start up and this would just prevent it from doing so longer. IE: Basically it's for racing mods...........and not day to day traffic. I would keep your 180* in there like I did and put in a cooling fan switch(for L98's you can find em in the mall here or through Mid America where I scored mine) to kick em on at 200* and off at 185*. This will allow it to automatically fix the heat prob..........and if that doesn't work...........use the manual fan as backup and put the switch in your console to kick it on in mind traffic. Add some Water Wetter™ in place of the anti-freeze(Never mix em I heard or it may actually ADD to the problem rather than help fix it.) with some water, make sure you're usin some good lubricant etc. and your prob should be no more. Picture this....................I was runnin a black vette and reving it high in 103* degree Arizona traffic and before the heat used to come out of the vents it was so hot...............but now even the cup holder stays cool which is amazing to me. Actually in mid day here I just have the switch for the manual fan wired under the hood and have it switched on every time I turn the ignition on. Which by the way is damn cool cuz you dont have to have the engine running. If anyone wants to know..........THIS IS HOW you cool your vette fast when you're parked for a rest after u just smoked a stang :D It's wired to where the only thing that has to be on is the ignition for both fans to kick in.............doesn't have to be the engine.

 

I know this may sound dumb but, get on ur knees and look into the air opening, there may be debris in there. I was driving once and a garbage bag got sucked and covered my rad. my temp went slowly up al the way into the red zone...... then i remmebered that bag i ran over dissapeared behind me :p: . i would reccomend a coolant flush as well.. coolant doesnt do a very good job if its been in the system for a while. GL!!