I bought the car from Nevada, brought to Ct.
All stock cooling system, 190 stat. Water only in system.
When I got to drive it last summer, the car warmed up to ~200 and held steady as I drove, through town etc. On the freeway, extended 65+mph, temp climed +10-20 degrees. Back on secondary roads, temp would slowly drop back to ~200.
When I start any drive, I go through 6-7 lights at slow speed before I get to open roads. temp stays steady. However, after driving and coming from open road, going through thouse same 6-7 lights at slow speed, the temp climbs steady +20-30 degrees!

On any road, as soon as I turn on the A/C, temp climbs steady - up to +30 degrees, even driving under 50mph, not too hot day, temp runs 220+ A/C on, ~200 A/C off.

Here is what I've done since:
1. new engine and heads, never removed the radiator, no cooling changes.
test drove and during tuning - same water temps as before.
2. tested fans - come on as programmed and come on with A/C switch.
Changed fan on/off settings with no noticable change in temp while driving = same as before
3. removed 190 stat, installed 160 stat. lowered fans on to be @175, kick off when under 160 (exact settings vary slightly)
Driving temp lowered to ~180 while warmed up and first driving. On freeway temp climbs to ~200, same dramatic temp climb when A/C turned on. Also temp climbs after a drive going through 6-7 stop lights to my house. the stop and go at slow speed AFTER driving awhile, temp climbs +20-30 degrees.
Pretty much same issue, but at a lower starting temp.
4. changed out radiator for new stock unit. filled 50/50 water/antifreeze mix.
Warmed up and first drive at ~180 as before. Freeway 65+mph climbed to ~200, turn on A/C instant climb to ~230 degrees. A bit worse with antifreeze and new radiator.
5. drained and filled with distilled water and WaterWetter. Sat idling for 30 minutes during flush/fill steady at ~180. no test drive (raining). I can see the water pumping steady stream into radiator as it is filled. Turned on A/C = instant climb to 200 degrees then I shut it all off. Fans were running.

So, since I bought this car and made several changes - the temp climbing issue through stop/go traffic and when A/C turned on has remained constant.
Any ideas?

*temps noted are both by dash gauge and laptop logging w/Datamaster.

 

more air flow = higher temp? weird. possibly water pump? higher rpms around town its pumped enough water but lower rpms on freeway its not pumping that great? worn down?

 

Does it have an air dam?

http://www.hawksthirdgenparts.com/pr...r-Air-Dam.html

 

I thought of this also. I hate to throw parts and labor at it....
Sorry - yes, perfect condition.

FYI - the last fill up with water/WaterWetter, sitting still in my driveway - steady temp for 30+ minutes, turn on the A/C = instant temp climb. no drop in engine idle to speak of, just compressor clutch kicks in, fans are on - but temp climbs just sitting still (also during driving)

Air has been bled several times, at each system change.

 

Wrong thermostat for one thing. Stock LT1 thermostat is 180.

 

What I removed may have been a 180 - can't recall. I just wanted to try the 160, and verify it had a stat at all.
The temp is responding to the stat change - just still temp climbs under 3 situations:
1. when A/C is on
2. when traveling at freeway speeds for length of time
3. during stop and go traffic AFTER some normal driving.

Insight or experience with any one of these is appreciated.

 

Are you losing coolant?

 

No. Stays full, does not overheat. Everything, except the waterpump (because it felt fine and is not cheap) is new or rebuilt professionally.
I thought the temp climb issue would be resolved with my engine/head rebuild.
I lowered the compression a little and relaxed the tune for less risk of ANY damage.
It did not change this temp climb issue at all..

 

Are you using an actual LT1 t-stat?

 

Yes. the one removed and the 160 installed were ordered for and correctly fit the LT-1.

my main issue is = what would make water temp go up ~30 degrees by turning on my A/C?

 

I have seen leaky AC condensers (they leak oil compressor too) cause dirt to stick to it, restricting air flow through it and the radiator. Best to pull the radiator and pressure wash the condenser out from the rear.

As for the temp going up with the AC on, the condenser gets hot, making the air coming through radiator hot.

Tired electric cooling fans that don't run as fast as they should, thus moving less air.

I guess you lowered the cooling fan control temps for the 160 'stat?

 

I hate to throw parts at any problem without good reason, but this stumps me. Keeping it simple, on a car from the 60's or 70's I'd have installed a new water pump, new/large capacity (factory) radiator, a good quality fan with proper shroud. Cheaper and less labor on those cars.
But on this 95, I really hope to hit the mark on my next try.
Can I remove and test my fans somehow? Or is it pretty safe to just replace them as my next step?

 

I would think if the fans had slowed enough to cause overheating you could
hear the difference and probably feel it on your hand held behind them while running, compared to another that has no cooling problems.
Real scientific, right? Sorry that I know of no test.

 

Ed is right about washing the rad and condenser, Sand and dust reduce the heat transfer a lot. Also a 50/50 mix of antifreeze and water would help. It does raise the boiling point.

 

Did you check to see if your temperature gauge is accurate? I assume you are using the dash gauge with the sensor in the head. Mine has been horribly unreliable. Then there's the rad cap, and if that's not it, you need to do a pressure check on the system.

 

Thanks or the reply.
It actually does not get to overheating - just climbs ~30 degrees from normal operating temp under the 3 conditions listed previously.
I had a kooky test idea - put a voltage booster (as used with fuel pumps) to the fans power source. Perhaps that would tell me something...

As mentioned, I had already cleaned the condenser and run 50/50 antifreeze. Same results.

As mentioned, I am reading both the dash gauge and PCM via Datamaster = same readings.
I suppose I could try and raise the radiator cap pressure a little..I have pressure checked the system and found no leaks.