I have a 90 civic si, d16a6 pretty much stock, When the ac is on and starts blowing cold after 15-20 mins, itll start to over heat but when the ac is off it wont ever overheat. I recently changed out my radiator because i thought it wasnt recirculating properly and the only other thing i can think of that might be the problem is waterpump?

 

The tricky thing is when you turn on your AC, it should start the condenser fan automatically. so that should start pulling more air through your radiator than it was, and is probably why no one replied because it doesn't make much sense. when you turn on your ac, it should also idle the car up a bit.

All of this leads me to believe that your AC compressor might be going bad, because it is putting such a load on the engine it is causing the engine to overheat. is there any belt squeel? You should start getting cooler air in about 30 seconds.. so 15-20 mins is way too long, and may also indicate that the compressor is going out. Finally, you can buy an AC refill bottle with a pressure guage at walmart for like $20, so pressure test the system to determine that it has the proper pressure. It should have pretty good pressure otherwise the electromagnetic clutch will not engage. if it is over filled however, it may also cause issues. You can bleed off some of the pressure in the ac system if you need to with the walmart pressure guage , but I think its a federal offence if you do so..

 

the compressor is brand new, and the funny thing is it only happens sometimes and the air gets cold after a minute or so but itll start to overheat around 15-20 mins but i do need to check the pressure

 

brand new autozone or brand new honda? either way, check the pressure before going any further.

 

is your fan turning on? maybe your condenser is blocking ari to the radiator? i know my ac condenser was beat to ****.

 

the thermostat might need to be replaced.

 

thats what i was thinking the thermostat needed replacing i actually replaced it today and it seems to be running fine hasnt overheated, im just not sure what the optimum heat level should be reading on the cluster because i remember before i ever had overheating issues it would read a little over the 1/4 mark just right below the thermometer picture. But now it reads right below the 3rd notch on the thermometer picture.

The compressor is reman Honda, brand new internals.

 

huh. I would pressure test the cooling system then. If you have a pressure leak, its cooling ability is reduced significantly. Are you leaking coolant or seeing white smoke ever?

 

nope, not that i know of, and none of my buddies have told me that they have seen white smoke. but when i replaced the compressor i got the factory specs on how many oz the compressor holds and its either 1 oz over or below, but ill pressure test it tomorrow.

 

Believe it or not it could also be a bad ground causing your gauge to slowly rise up. Check all your grounds being that you took out and installed a part, you might have accidentally knocked something loose or forgot to install one altogether.