Join Date: May 2019
iS-10 till 12 is offline
Re: Running hot with AC on
IF you drive in really dusty areas, like on a long gravel road, dirt roads, etc., the actual fins can start caking up with dirt. I used to have an issue with a semi I drove and despite having a radiator the size of a car hood and a mechanical fan the size of a beach ball, it started running hot.
Can remove the front grill, then carefully take a garden hose w/o the nozzle, just let it flow out the open hose end. Run the water through the fins, being careful to not touch the fins or they'll bend. Watch the flow of water out the other side (fan shroud side). If it's dark/dirty water, or flow is weak, there's a build up of dirt. Hold hose there until clear water is seen coming out. I suggest starting at one end and slowing moving across to the other, then go down 1 row of fins, and start over.
It takes 5-10 minutes and is easy enough to rule out if it's getting dirty and losing efficiency. If you drive through occasional rain and rarely dusty areas, it typically stays clean w/o intervention. But if no rain over a long period, dirt can build up.
If the internal rows (remove the cap when cold, look into the opening; squeeze the upper radiator hose if needed as it'll force some coolant out the radiator cap opening allowing you to see more rows) are showing white calcium build up on the row ends, then chances are tap water is in the system, and the radiator has been slowly choked to death as deposits have accumulated, and it's now bad enough that the radiator can't cool at idle under AC load. Just replace it if that's the case and use distilled water ONLY. Can buy gallon jugs for a $1 something at most grocery stores. You can use 50/50 pre-dilluted, but they are charging you for the water in the pre-diluted mix. Even though it costs a little more, it's smarter to mix it yourself. Two 50/50 jugs are ONE non-diluted coolant jug split with water.
You stated your fan made contact with the shroud? It might have bent a blade or numerous blades. If a blade is bent (even the tip of the blade), the fan will lose a ton of efficiency and have a bad imbalance that'll probably kill the water pump prematurely. If the fan was damaged, replace it ASAP.
The biggest thief is time.