Fan questions

[bobmook]

Just got the AC serviced for summer (it's the first summer I've had the vette) and the results thus far are bad. The car wants to get hot when I use the ac. (It just gets hotter and hotter while the ac is on and its idling) I checked for debris between the condensor and the radiator, there was some but not as musc as I've heard there would be. I was able to get most of it out. No change. I could hear the fan running while the ac was on, but then I got to checking. First of my all fan come ons on around 229 defrees and cools until the car gets to about 221 then shuts off. Second of all I got out of the car w/ the ac running and the fan looked a bit lazy to me so I reached in w/ my hand and stopped it. Now that doesn't seem normal to me that I could do that (I was expecting it to hurt my fingers).
Can anyone help w/ what's going on here? I mean the fan does cool the car down(some) w/out the ac running.

 

[Jeb]

Sounds to me like the fan is loose on the shaft of the motor. If that's the case, you're probably not packing much air into the radiator when it's running.

 

[bobmook]

Sounds to me like the fan is loose on the shaft of the motor. If that's the case, you're probably not packing much air into the radiator when it's running.

I'll look into that but I can't imagine it would cool from 229 to 221 if the fanblade was that loose. I'm wondering if there may be two levels of fan activity. Hell I'm just wondering at this point.

 

[GS977]

if you can stop the fan with your hand then you have a problem, or very strong hands .
its very hot down here in south louisiana, and mine used to run @220 with the air on. i put both my fans on a manual switch then added a big fan in front of the radiator. i have a 160 therm in it. now it doesnt matter how hot it is, it runs @ 160-170 w/o the air on and @190-200 with the air on in mid to upper 90 degree wheather.
i think my motor runs hotter then a stock lt4 would anyway with it being a built 383

 

[warren s]

The fan is definitely bad, either the blade is loose or the motor is going. If you can stop it with your hand, it not running any where near full speed.

I have done alot of work with fans on C4s and C5s (Check my webiste) I had a fan out of an 86, it was clamped into my vise on my workbench with the blade attached. Putting my hand into the spinning blade would have chopped off a finger no problem.

 

[geekinavette]

Agreed...if you can stop it when it's running then you have a problem. Also, the fan should be on if the AC is on (and building refrigerant pressure) regardless of temperature. The temps you listed are about right for turning the fan on/off...IF the AC is not on. You can put a lower temp switch in it for the fan, it's in the pass. side cylinder head (single wire).

Bill

 

[bobmook]

Well to-day I went out and started the car w/ the ac on and just watched. What appears to be happening is the fan comes on for a while then stops. I suspect the compressor is kicking on and off thus starting and stopping the fan. This wouldn't be so bad except it appears when the ac is on the compressor has complete control of the fan (i.e. when the car reaches 229 the fan doesn't appear to run automatically until it cools down some.) Is there some way to override the controls and just make the fan run when I want it to? I mean I know about fan override switches but wouldn't it throw a code if I used an override when the AC is running? Or do I need to replace the compressor?

 

[geekinavette]

The fan should not start and stop with the AC compressor. It's not necessarily abnormal for the compressor to cycle like that...but the fan should just be on any time the AC is on, whether the compressor clutch is engaged or not. Maybe have the pressure checked in the AC system.

The AC fan switch and the coolant temp fan switch are connected in parallel...EITHER of them can control the fan. If the AC is off then it is controlled only by the coolant switch...if the AC is on then the fan should be on...period.

Bill

 

[WaveDoggie]

Yeppers, what Bill said, and your fan motor is shot. They are very common, and can be scored for as little as $15 in a junkyard (Buicks and some Camaros use the same 'sweep-bladed' fans.

 

[bobmook]

Installed a new fan motor and rigged up an override so I can make the fan run all the time. The car runs cool w/out ac but as soon as I turn on the AC the temp starts ever so slowly climbing (this w/ the fan running constantly). I'm just out of any answers (I also noticed when the AC is on there's a sort of juddering combination of vibration and noise in the car).

 

[geekinavette]

Do you still have the issue of being able to stop the fan when it's running? That's a problem.

The temperature will go up some with the AC on...since you're now drawing air into the radiator that has already been heated up by the AC condenser.

Bill

 

[bobmook]

Do you still have the issue of being able to stop the fan when it's running? That's a problem.

Bill

No that was cured (way cured) w/ the new fan motor.

 

[geekinavette]

Ahhh ok, very good.

What is the temp getting up to with the AC on?

Bill

 

[bobmook]

I only let it get to 207 to-day, since by that time it seemed I'd established an inexorable pattern. W/out the ac and the w/ the new override running I doubt it would get beyond the 190's

 

[scorp508]

(I also noticed when the AC is on there's a sort of juddering combination of vibration and noise in the car).

I don't know if this will apply to your 84, but there is a TSB for '87 that recommends installing a brace over in the power steering area to cure the symptom you speak of.

 

[geekinavette]

I only let it get to 207 to-day, since by that time it seemed I'd established an inexorable pattern. W/out the ac and the w/ the new override running I doubt it would get beyond the 190's

Getting up to 220 or so on a hot day in traffic is pretty normal. I don't like those kind of temps any more than you do (neither does the transmission)...but it is nonetheless normal.

Bill

 

[Crucifix]

Just got the AC serviced for summer (it's the first summer I've had the vette) and the results thus far are bad. The car wants to get hot when I use the ac. (It just gets hotter and hotter while the ac is on and its idling) I checked for debris between the condensor and the radiator, there was some but not as musc as I've heard there would be. I was able to get most of it out. No change. I could hear the fan running while the ac was on, but then I got to checking. First of my all fan come ons on around 229 defrees and cools until the car gets to about 221 then shuts off. Second of all I got out of the car w/ the ac running and the fan looked a bit lazy to me so I reached in w/ my hand and stopped it. Now that doesn't seem normal to me that I could do that (I was expecting it to hurt my fingers).
Can anyone help w/ what's going on here? I mean the fan does cool the car down(some) w/out the ac running.

Hi Dude,
Last summer while I sat in traffic my temp got up to 225 on then would cool to around 200 and that was without the AC on. This year I went for the tranny fluid change(not that it has a lot to do with it but you never know) and flushed the coolant system. It is still too early to tell this summer but I have not seen 225 yet even with the AC on.

 

[bobmook]

Ok I want to make sure I understand. The other day (it was 92) I let the vette sit in the driveway and idle until I got to 222. At that point I shut it off but it seemed like it was just going to continue climbing. (You have to understand I have a Jaguar XJ-S which cost me $4000 in rebuild fees because someone [the previous owner whom I later discovered was an exotic dancer] let the car overheat so I'm a bit paranoid about such things) Now this was w/ the fan going full bore. This is normal behavior?

 

[WhalePirot]

The Geek is right on with this, as usual. BTW, the '87 setup is fairly diferent than the '84.

I would be suspect about the condition of your cooling system, i.e. the flush, fresh fill, theromostat,etc., but it seems to cool okay until you turn on the A/C. I wonder if the compressor is dragging too much, causing the shudder and loading the engine down, causing the increased temperatures. I don't know a home check for that; perhaps someone else does.

A good way to check if more radiator capacity is needed, is bringing the heater core 'online'.

I was not comfy, but have seen 250 w/o a problem. I don't, however, let the engine just heat up so much,then shut it off, as the heat continues to build. It is better to allow the cooling system to cool it down, if you can figure a way. Driving gently works, but a fan blowing onto the car can also.

 

[Vettefan87]

I was not comfy, but have seen 250 w/o a problem. I don't, however, let the engine just heat up so much,then shut it off, as the heat continues to build. It is better to allow the cooling system to cool it down, if you can figure a way. Driving gently works, but a fan blowing onto the car can also.

Yeah, your coolant can easily spike 10-20 degrees once you turn off the motor. Definetly make sure you have enough antifreeze, and it is of good quality.