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View Full Version : Temp goes from 200 to 225 when A/C is on


Prez1967
08-22-2023, 03:08 PM
I cant recall if this was the case since I bought my car but I recently noticed that when Im cruising around without A/C, the car is at a stead 200-202 degrees.

When I turn the A/C on, the car's water temp creeps up to 223-225.

Is this normal? or do I have to roll my sleeves up and dig in...

Jagdpanzer
08-22-2023, 05:58 PM
What radiator do you have installed?
What temperature are the fans programmed to come on?


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Prez1967
08-23-2023, 09:31 AM
What radiator do you have installed?
What temperature are the fans programmed to come on?


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I have an aluminum radiator in the car now. I flushed it not long ago when I did suspension work and steering rack since I removed it and Haibeck also flushed system when it was up with him at the beginning of the year.

He also programmed the car to run fans at 160 or 180 I think? Whatever his standard practice is.

Dynomite
08-23-2023, 12:38 PM
I cant recall if this was the case since I bought my car but I recently noticed that when Im cruising around without A/C, the car is at a stead 200-202 degrees.

When I turn the A/C on, the car's water temp creeps up to 223-225.

Is this normal? or do I have to roll my sleeves up and dig in...

Haibeck both fans on 205 off 200.....
What was air temperature?
What was engine rpm? You say cruizing so must be over 2,000 rpm unless you are in 6th....

With AC on engine temp may rise a bit...

Prez1967
08-23-2023, 12:42 PM
Got my stats mixed up.

T-stat is either 160 or 180 (dont remember) fans are set to whatever Marc's standard set up is.

Intake Air Temp?

It was SUPER hot a couple weeks ago when I was driving around in heavy traffic and with the A/C off, the temperature was stable at 200 degrees. When I'd click on the A/C it would stabilize at 225. Same result when I was going highway speeds.

It was considerably cooler the last time I drove the car had the same results.
Im planning on driving the car tonight. Can check air temp tonight and report back

Young1
08-23-2023, 10:10 PM
I am experiencing the same thing as OP. Never have before. All is clean. Is it possible 30 year old thermostat is not fully opening? I ordered an NOS Stant 14068 on eBay today.

Dynomite
08-24-2023, 12:55 AM
I am experiencing the same thing as OP. Never have before. All is clean. Is it possible 30 year old thermostat is not fully opening? I ordered an NOS Stant 14068 on eBay today.

Marc Haibeck suggested at one time the older Stants will deteriorate (Decrease in FUll Open Area) by up to 15% as they age. A thermostat with over 50k miles generally opens 5 degrees later and opens about 85%.

longhorns05
08-24-2023, 02:42 PM
I ordered an NOS Stant 14068 on eBay today.

I tried a Stant t-stat 3 yrs ago, it never worked right out of the box. The car consistently ran hot until I swapped it out. Especially being in FL, it might be a good idea to look into a lower temp t-stat from Marc or Corey

Young1
08-24-2023, 02:45 PM
Well, if Marc says it I believe it. I was only guessing but the Man knows. At 75k miles I am due for replacement. I will follow up after I install it.

longhorns05
08-24-2023, 02:46 PM
When I turn the A/C on, the car's water temp creeps up to 223-225.

Is this normal? or do I have to roll my sleeves up and dig in...

Have you checked to make sure both fans are running when this happens?

Dynomite
08-24-2023, 05:19 PM
I tried a Stant t-stat 3 yrs ago, it never worked right out of the box. The car consistently ran hot until I swapped it out. Especially being in FL, it might be a good idea to look into a lower temp t-stat from Marc or Corey

Post 7 - Thermostats, Fans, Water Pump, and Radiators (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp.html#post1580070558)

Prez1967
08-25-2023, 08:35 PM
I'll check the fans.

I doubt its a t-stat as efficiency would likely be compromised whether the A/C was on or off. I have spares but we'll see.