Car gets hot when moving w/ AC on

[Diabolic]

Ok it looks like the Tx heat is getting to the Cobra. Today I noticed that when cruising with the AC on the temp needle will creep up to the "L" in normal. I turn off the AC and it drops back to the "R". It won't get past the "M" when sitting at idle with the AC on, it's only when at speeds from 5-45mph in stop and go traffic. The cap is a new 16#, the Radiator is a big 2 Row Griffen, and both fan speeds are working properly. I'm quite certain it isn't the fans because it only does this when moving down the road. Could being low on Freon cause this situation? Could the condensor be freezing up and blocking airflow? I'm going to flush the radiator with vinegar this weekend, but I'm still a little stumped.

[gip99gt]

change out thermo and see if it still runs hot.

[Diabolic]

Well my thermo is a 195 and I did some datalogging today. The ECM says the car gets as hot as 222º with the AC on and runs at 204 with the AC off. The stock gauge was decieving because it looks really hot with the needle sitting on the A in NORMAL. 222 is still a little warm for my taste but looking back at previous datalogs my ecm was saying the car was 204-208º when it was in the lower 90's oputside. It's about 10º warmer today so i'm sure it has an effect. I'll be cleaning the radiator with vinegar this weekend, and I may even replace the wp. When the car is at idle all the water in the radiator is doing is a little sloshing around. When I rev it it sloshes more but the coolant never drops. I reused my old waterpump when I changed a bunch of stuff several months ago so it has close to 70,000 miles on it.

[BlackGT]

in addition to the above, if you want it to run cooler, changing to a cooler thermo will help...

[Diabolic]

I'm not so sure about that. Running 222º the termostat is already open all the time. I just purchased a stock air dam as mine has been long gone for years. Perhaps this will help with the 15-40mph cruising temps.

[Diabolic]

Just ordered a Ford Racing waterpump.

[JC316]

What year is the cobra? I can almost guarantee you that it's the radiator and if it's a 96/97, I can 100% guarantee it. My 96 GT 4V ran warm, like up to 235*F if the ambient was over 100*F and it was the radiator.

[91CoupeMike]

Mine was not Wanting to cool today in city driving.. Bunch of red lights.

Normally it sits about 1/4 way up the gauge or lower, but today it was more like 1/2 gauge and not cooling just staying constant.

I normally run with the fans off unless I stop and never have issues. I guess it's just hot as hell outside.

[JC316]

Mine was not Wanting to cool today in city driving.. Bunch of red lights.

Normally it sits about 1/4 way up the gauge or lower, but today it was more like 1/2 gauge and not cooling just staying constant.

I normally run with the fans off unless I stop and never have issues. I guess it's just hot as hell outside.

Stop an go overheating usually indicates a fan issue, highway and A/C overheating usually indicates a radiator issue. Since you aren't running fans, that is the reason it was getting warm.

[91CoupeMike]

Stop an go overheating usually indicates a fan issue, highway and A/C overheating usually indicates a radiator issue. Since you aren't running fans, that is the reason it was getting warm.

I have fans I just didn't have them switched on until it was too late, then it wasnt cooling very well. Didn't get any hotter but sure wasn't cooling down.

They are dual fans from a 91 Nissan sentra and I'm using the stock 1 core radiator with under drive pulleys. < not a good cooling system by any means.

I need a 2+ core with a mark 8 or Taurus fans.

[Diabolic]

It's a 95 with a $500 aluminum Griffen radiator. Aluminum with 2 1.25" rows. I'm kinda thinking the thermostat closed crooked. This has happened to me twice already.

[Slow Five-O]

Check thermostat like mentioned and also try some water wetter.

[71chevellejohn]

in addition to the above, if you want it to run cooler, changing to a cooler thermo will help...

Changing to a lower temp thermostat will not correct an overheating problem - it could make it worse.

[SEB]

My 95GT runs Cool with the AC on. But im not sure what thermastat I have in it. Just know it runs cool

[91CoupeMike]

My 95GT runs Cool with the AC on. But im not sure what thermastat I have in it. Just know it runs cool

No way!